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  • 101.
    Asplund, Max
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Surface modified cellulose and starch biocomposite with a low melting point polyamide2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The search for an environmentally friendly general purpose polymeric material has led to biomaterials being an active component in development of plastics. The biomaterials decrease the usage of oil-based polymers, as a proportion of the final material is from the nature. This thesis investigates the benefits of adding biopolymers to a low melting point polyamide (PA1216), which was polymerised through polycondensation of 1,12-diaminododecane and 1,16-hexadecanediocic acid. The low melting point allowed the polymer to be processed with at a lower temperature than conventional polyamides. Furthermore, the lowered temperature allowed thermally stable processing with biopolymers, such as cellulose and starch. Blends of PA1216 and cellulose or starch were extruded into filaments, hot pressed into films, and characterised. The images obtained from Scanning Electron Microscopy (SEM) showed inadequate interaction between the phases. This was further solidified with results from differential scanning calorimetry, dynamic mechanical analysis, and mechanical testing. In order to improve the interaction between the phases, both cellulose and starch were modified with a surface modification agent. Fourier Transform Infrared Spectroscopy and Thermal Gravimetric analysis were employed to confirm the modification. Similarly, the modified biopolymers were extruded with PA1216. SEM images showed improved interaction between PA1216 and modified biomaterials. The cellulose surface was roughened, and clusters of starch were fragmented, which led to improved dispersion of cellulose and starch in the matrix. The improved interaction was also observed in mechanical properties, as the modified biomaterial composite were able to withstand a greater amount of force. Finally, the incorporation of cellulose to PA1216 decreased the water vapour permeability, even more so with modified cellulose. The permeability results for starch composites were inconclusive, whenever starch was modified or not. Concluding, the modified cellulose and starch showed improved interaction with PA1216 compared to neat cellulose and starch composites, thus confirming the benefits of surface modification. The modified cellulose and starch composites did not outperform the neat PA1216. However, both modified biopolymers should be further studied, as there are notable benefits with the modification.

  • 102.
    Asta, Nadia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Fundamentals of Interactions between Cellulose Materials and its Implications on Properties of Fibrous Networks2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fundamental research plays a pivotal role in the development of sustainable solutions that benefit both our environment and everyday lives. Cellulose, as an abundant and renewable resource, holds immense potential for sustainable applications. However, navigating the complexities of molecular and supramolecular structure of cellulose poses significant challenges in harnessing its full potential. By delving into fundamental research, we aim to uncover the underlying mechanisms governing cellulose interactions, paving the way for innovative advancements in sustainable material development.This thesis uncovers the intricate relationship between fundamental research and applied methodologies by showing how molecular contact and structure at the interface of cellulose-rich materials will control the development of the macroscopic mechanical properties of networks from cellulose-rich fibres. The study encompasses various facets, ranging from the development of model materials for studying interfacial interactions to the preparation of fibrous networks with tailored properties.In the initial part of the work the research delves into the development of model materials to investigate interactions at smooth interfaces of regenerated cellulose. The study reveals the crucial role of the making and breaking of cellulose interface, or sometimes interphase, in the development of adhesive joints. Experimental findings demonstrate how chemical additives influence the interactions between cellulose surfaces, thereby modulating the structural and adhesive properties at the interface. Furthermore, by utilizing model materials, insights are gained into fibre-fibre interactions and the influence of surface treatments on network formation and mechanical performance. Lastly, the research focused on investigating the preparation of fibrous networks at different densities and amount of adsorbed additives, providing a comprehensive understanding of how network density and composition affect mechanical properties of the networks.This work not only exemplifies a synergistic approach, where fundamental insights into molecular contacts and interface structures are translated into practical applications for enhancing macroscopic properties but also highlights the importance of integrating fundamental and applied methodologies in molecular engineering, offering novel strategies for advancing sustainable paper production practices and contributing to the attainment of sustainable development goals.

  • 103.
    Asta, Nadia
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Kaplan, Magdalena
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Kulachenko, Artem
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Influence of density and chemical additives on paper mechanical propertiesManuscript (preprint) (Other academic)
  • 104.
    Asta, Nadia
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Loist, Maximilian
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Model Systems for Clarifying the Effects of Surface Modification on Fibre-Fibre Joint Strength and Paper Mechanical PropertiesManuscript (preprint) (Other academic)
  • 105.
    Asta, Nadia
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. RISE Research Institute of Sweden, SE-114 86 Stockholm, Sweden.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    The Use of Model Cellulose Materials for Studying Molecular Interactions at Cellulose Interfaces2023In: ACS Macro Letters, E-ISSN 2161-1653, Vol. 12, no 11, p. 1530-1535Article in journal (Refereed)
    Abstract [en]

    Despite extensive research on biobased and fiber-basedmaterials, fundamental questions regarding the molecular processesgoverning fiber−fiber interactions remain unanswered. In this study, weintroduce a method to examine and clarify molecular interactions withinfiber−fiber joints using precisely characterized model materials, i.e.,regenerated cellulose gel beads with nanometer-smooth surfaces. Byphysically modifying these materials and drying them together to createmodel joints, we can investigate the mechanisms responsible for joiningcellulose surfaces and how this affects adhesion in both dry and wet statesthrough precise separation measurements. The findings reveal a subtlebalance in the joint formation, influencing the development ofnanometer-sized structures at the contact zone and likely inducingbuilt-in stresses in the interphase. This research illustrates how model materials can be tailored to control interactions betweencellulose-rich surfaces, laying the groundwork for future high-resolution studies aimed at creating stiff, ductile, and/or tough jointsbetween cellulose surfaces and to allow for the design of high-performance biobased materials.

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  • 106.
    Atoufi Najafabadi, Zhaleh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Development and Tailoring of Low‐Density Cellulose‐Based Structures for Water Treatment2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The challenges posed by our limited clean water sources and the well-known global water pollution demand more efficient water purification technologies. Additionally, the increasing environmental awareness has inspired a shift towards eco-friendly and renewable materials and technologies. This thesis is focused on developing effective adsorbent materials from renewable resources to eliminate organic solvents, dyes, and metal ions from water. Cellulose, the most abundant biopolymer in nature, is the main component used to develop new materials in the present study. Its distinctive physical and colloidal properties, in the form of nanocellulose, along with tunable surface chemistry, play key roles in enhancing the effectiveness of the developed materials.

    The primary focus of the first part of the thesis was to develop a molecular layer-by-layer modification technique to customize the surface functionality of cellulose aerogels in a uniform and controlled manner. Through the sequential deposition of diamine and triacid monomers, exceeding lythin polyamide coatings were formed on the cellulose aerogels, altering the surface properties from hydrophilic to hydrophobic. This transformation made them well-suited structures for oil-water separation.

    Following this, a biohybrid aerogel was developed based on cellulose nanofibrils (CNFs) and amyloid nanofibrils (ANFs), the latter derived by heat treatment of β-lactoglobulin proteins. The pH-tunable surface charge of the aerogel, controlled by the amphiphilicity of the protein, allowed for the adsorption of both cationic and anionic contaminants by adjusting the pH of the solutions. Furthermore, the aerogels exhibited remarkable selectivity for lead (II) ions and they could also be regenerated and reused after each adsorption cycle without a significant loss of their adsorption capacity. This was to a large extent possible due to the excellent wet stability of these aerogels, which was achieved by crosslinking the CNFs during freezing and ice templating, eliminating the need for freeze-drying. However, a solvent exchange to acetone after melting was still necessary to reduce the influence of the capillary forces during drying to avoid the collapse of the aerogels. In a consecutive study, the foaming characteristics of the heat-treated β-lactoglobulin system were exploited to create highly stable Pickering foams with the aid of using CNFs as stabilizers and to physically lock the system through a controlled pH reduction. Interestingly, these Pickering foams could be directly oven-dried without collapsing, yielding low-density foams. Furthermore, it was demonstrated that the foams can be chemically crosslinked by incorporating chemical crosslinkers in the formulation or by pre-functionalizing the CNFs with dialdehydes. This crosslinking naturally also provided wet stability to the oven-dried foams.

    Finally, an innovative and environmentally friendly method was introduced to increase the charge of cellulose fibers by radical polymerization of acrylic acid from the fibers, enabling the preparation of fibers with an exceptionally high charge of 6.7 mmol/g. The introduction of these charged groups significantly enhanced the interaction of the fibers with methylene blue as a model dye and lead (II), Copper (II), and Zinc (II) ions as model metal ions, showing the huge potential of these fibers as building blocks for a wide range of adsorbent applications. Overall, this thesis demonstrates the development and characterization of several bio-based adsorbents for water remediation.

  • 107.
    Atoufi, Zhaleh
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ciftci, Göksu Cinar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Green Ambient-Dried Aerogels with a Facile pH-Tunable Surface Charge for Adsorption of Cationic and Anionic Contaminants with High Selectivity2022In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 23, no 11, p. 4934-4947Article in journal (Refereed)
    Abstract [en]

    The fabrication of reusable, sustainable adsorbents from low-cost, renewable resources via energy efficient methods is challenging. This paper presents wet-stable, carboxymethylated cellulose nanofibril (CNF) and amyloid nanofibril (ANF) based aerogel-like adsorbents prepared through efficient and green processes for the removal of metal ions and dyes from water. The aerogels exhibit tunable densities (18-28 kg m-3), wet resilience, and an interconnected porous structure (99% porosity), with a pH controllable surface charge for adsorption of both cationic (methylene blue and Pb(II)) and anionic (brilliant blue, congo red, and Cr(VI)) model contaminants. The Langmuir saturation adsorption capacity of the aerogel was calculated to be 68, 79, and 42 mg g-1for brilliant blue, Pb(II), and Cr(VI), respectively. Adsorption kinetic studies for the adsorption of brilliant blue as a model contaminant demonstrated that a pseudo-second-order model best fitted the experimental data and that an intraparticle diffusion model suggests that there are three adsorption stages in the adsorption of brilliant blue on the aerogel. Following three cycles of adsorption and regeneration, the aerogels maintained nearly 97 and 96% of their adsorption capacity for methylene blue and Pb(II) as cationic contaminants and 89 and 80% for brilliant blue and Cr(VI) as anionic contaminants. Moreover, the aerogels showed remarkable selectivity for Pb(II) in the presence of calcium and magnesium as background ions, with a selectivity coefficient more than 2 orders of magnitude higher than calcium and magnesium. Overall, the energy-efficient and sustainable fabrication procedure, along with good structural stability, reusability, and selectivity, makes these aerogels very promising for water purification applications.

  • 108.
    Atoufi, Zhaleh
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Cortes Ruiz, Maria F.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Olsen, Peter
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Extremely highly charged wood fibers via a green radical grafting from method towards water remediationManuscript (preprint) (Other academic)
  • 109.
    Atoufi, Zhaleh
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Gordeyeva, Korneliya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Cortes Ruiz, Maria F.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Hall, Stephen A
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics.
    Larsson, Per A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wet-resilient foams based on heat-treated β-lactoglobulin and cellulose nanofibrilsManuscript (preprint) (Other academic)
  • 110.
    Atoufi, Zhaleh
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Gordeyeva, Korneliya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Cortes Ruiz, Maria F.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Larsson, Per A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Synergistically stabilized wet foams from heat treated β-lactoglobulin and cellulose nanofibrils and their application for green foam productionManuscript (preprint) (Other academic)
  • 111.
    Atoufi, Zhaleh
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Surface tailoring of cellulose aerogel-like structures with ultrathin coatings using molecular layer-by-layer assembly2022In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 282, article id 119098Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibril-based aerogels have promising applicability in various fields; however, developing an effi-cient technique to functionalize and tune their surface properties is challenging. In this study, physically and covalently crosslinked cellulose nanofibril-based aerogel-like structures were prepared and modified by a mo-lecular layer-by-layer (m-LBL) deposition method. Following three m-LBL depositions, an ultrathin polyamide layer was formed throughout the aerogel and its structure and chemical composition was studied in detail. Analysis of model cellulose surfaces showed that the thickness of the deposited layer after three m-LBLs was approximately 1 nm. Although the deposited layer was extremely thin, it led to a 2.6-fold increase in the wet specific modulus, improved the acid-base resistance, and changed the aerogels from hydrophilic to hydrophobic making them suitable materials for oil absorption with the absorption capacity of 16-36 g/g. Thus, demon-strating m-LBL assembly is a powerful technique for tailoring surface properties and functionality of cellulose substrates.

  • 112. Attias, N.
    et al.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Mijowska, S. C.
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Isaksson, M.
    Pokroy, B.
    Grobman, Y. J.
    Abitbol, T.
    Biofabrication of Nanocellulose–Mycelium Hybrid Materials2021In: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 5, no 2Article in journal (Refereed)
    Abstract [en]

    Healthy material alternatives based on renewable resources and sustainable technologies have the potential to disrupt the environmentally damaging production and consumption practices established throughout the modern industrial era. In this study, a mycelium–nanocellulose biocomposite with hybrid properties is produced by the agitated liquid culture of a white-rot fungus (Trametes ochracea) with nanocellulose (NC) comprised as part of the culture media. Mycelial development proceeds via the formation of pellets, where NC is enriched in the pellets and depleted from the surrounding liquid media. Micrometer-scale NC elements become engulfed in mycelium, whereas it is hypothesized that the nanometer-scale fraction becomes integrated within the hyphal cell wall, such that all NC in the system is essentially surface-modified by mycelium. The NC confers mechanical strength to films processed from the biocomposite, whereas the mycelium screens typical cellulose–water interactions, giving fibrous slurries that dewater faster and films that exhibit significantly improved wet resistance in comparison to pure NC films. The mycelium–nanocellulose biocomposites are processable in the ways familiar to papermaking and are suggested for diverse applications, including packaging, filtration, and hygiene products.

  • 113.
    Ayalew, Bahiru Tsegaye
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials. Chalmers Univ Technol, Dept Chem & Chem Engn, Appl Chem, Kemivagen 10, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, FibRe Ctr Lignocellulose Based Thermoplast, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Strom, Anna
    Chalmers Univ Technol, Dept Chem & Chem Engn, Appl Chem, Kemivagen 10, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, FibRe Ctr Lignocellulose Based Thermoplast, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials. Chalmers Univ Technol, FibRe Ctr Lignocellulose Based Thermoplast, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Thermoplastic lignocellulose materials: A review on recent advancement and utilities2023In: Carbohydrate Polymer Technologies and Applications, ISSN 2666-8939, Vol. 5, article id 100319Article, review/survey (Refereed)
    Abstract [en]

    Lignocellulosic biomass is the most abundantly available resource in nature. However, its potential as a replacement of oil in plastic production has not been fully exploited. To reduce the carbon footprint, the use of lignocellulose biomass to produce bio-based plastics is attracting increasing global interest. The aim of this review article is to systematically summarize the recent advancements of the development of lignocellulose materials that possess thermoplastic properties, meaning they can be processed/shaped by common plastic processing techniques. The approaches used for modification of lignocellulose biomass and the properties of the modified materials, as well as factors affecting the properties of these, are discussed. The regulatory aspects and policy directions of bio-based plastics, including thermoplastic lignocellulose, are also mentioned. Current challenges of producing thermoplastic lignocellulose and the way forward to solve this are also explored.

  • 114.
    Ayyachi, Thayanithi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Stability of linoleic acid and its reactivity with bone cement components2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Acrylic bone cement is the gold standard in vertebral augmentation procedures. Modification of acrylic bone cement using linoleic acid has resulted in attractive properties that enable convenient handling by surgeons and reduce follow-up complications such as adjacent vertebral fractures. Even though the attractive properties of linoleic acid-modified bone cement are acknowledged, the understanding of how it imparts those properties remain unexplored. As a component in bone cement, linoleic acid needs to be sterilized before its use in bone cement. However, there are apprehensions whether autoclave sterilization of linoleic acid causes degradation. In addition, it is unclear what happens with linoleic acid in hardened bone cement over time. 

    In this thesis, sterilized and unsterilized linoleic acid were evaluated alone and treated with different components of the bone cement such as activator, initiator, monomer, and inhibitor, in the presence and absence of solvent, and the ensuing changes were monitored through 1H NMR and UV-VIS. The results showed that linoleic acid degraded due to sterilization and oxidation. The oxidation of linoleic acid depended on sterilization, temperature, solvent, and the amount of oxygen exposure. As confirmed through 1H NMR and UV-VIS, linoleic acid (sterilized and unsterilized) reacted with the activator, initiator, and monomer. These reactions could reduce the availability of the components for the in-situ polymerization of the monomer, thus altering the properties of the bone cement including convenient handling during the operation and reduced adjacent vertebral fractures post the operation.

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  • 115.
    Ayyachi, Thayanithi
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Pappalardo, D.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Defining the role of linoleic acid in acrylic bone cement2022In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 139, no 25, article id e52409Article in journal (Refereed)
    Abstract [en]

    Polymethylmethacrylate is clinically used as a bone cement in various orthopedic and trauma surgeries. Post the surgery, such conventional acrylic bone cement has been reported to cause adjacent vertebral fractures; modifying it by adding linoleic acid in the formulation has shown potential in averting such fractures thanks to bone-compliant mechanical properties, besides providing convenient handling properties. Although the resulting properties are attractive, the understanding of how linoleic acid imparts such advantageous properties remain unclear. Linoleic acid is typically sterilized in an autoclave before being used in the bone cement formulation; however, there are apprehensions whether the sterilization causes degradation. In this research, sterilized and unsterilized linoleic acid were evaluated alone and with different components of bone cement, such as activator, initiator, monomer, and inhibitor, and the ensuing structural changes in linoleic acid were monitored through 1H NMR and UV–Vis. The results reveal that linoleic acid degrade due to sterilization. In addition, evidence for reactions of sterilized/unsterilized linoleic acid with activator and initiator have been collected. We hypothesize that these reactions can reduce the availability of the components for the in situ polymerization of methyl methacrylate monomer and cause the improvement in handling properties and decrease in mechanical properties. 

  • 116.
    Babu, Karthik
    et al.
    Ctr Polymer Composites & Nat Fiber Res, Chennai 625005, Tamil Nadu, India..
    Rendén, Gabriella
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Mensah, Rhoda Afriyie
    Nanjing Univ Sci & Technol, Sch Mech Engn, Nanjing 210094, Peoples R China..
    Kim, Nam Kyeun
    Univ Auckland, Ctr Adv Composite Mat, Dept Mech Engn, Auckland 1142, New Zealand..
    Jiang, Lin
    Nanjing Univ Sci & Technol, Sch Mech Engn, Nanjing 210094, Peoples R China..
    Xu, Qiang
    Nanjing Univ Sci & Technol, Sch Mech Engn, Nanjing 210094, Peoples R China..
    Restas, Agoston
    Natl Univ Publ Serv, Dept Fire Protect & Rescue Control, H-1011 Budapest, Hungary..
    Neisiany, Rasoul Esmaeely
    Hakim Sabzevari Univ, Fac Engn, Dept Mat & Polymer Engn, Sabzevar 9617976487, Iran..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Forsth, Michael
    Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Struct & Fire Engn Div, S-97187 Luleå, Sweden..
    Bystrom, Alexandra
    Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Struct & Fire Engn Div, S-97187 Luleå, Sweden..
    Das, Oisik
    Luleå Univ Technol, Dept Engn Sci & Math, S-97187 Luleå, Sweden..
    A Review on the Flammability Properties of Carbon-Based Polymeric Composites: State-of-the-Art and Future Trends2020In: Polymers, E-ISSN 2073-4360, Vol. 12, no 7, p. 1518-Article, review/survey (Refereed)
    Abstract [en]

    Carbon based fillers have attracted a great deal of interest in polymer composites because of their ability to beneficially alter properties at low filler concentration, good interfacial bonding with polymer, availability in different forms, etc. The property alteration of polymer composites makes them versatile for applications in various fields, such as constructions, microelectronics, biomedical, and so on. Devastations due to building fire stress the importance of flame-retardant polymer composites, since they are directly related to human life conservation and safety. Thus, in this review, the significance of carbon-based flame-retardants for polymers is introduced. The effects of a wide variety of carbon-based material addition (such as fullerene, CNTs, graphene, graphite, and so on) on reaction-to-fire of the polymer composites are reviewed and the focus is dedicated to biochar-based reinforcements for use in flame retardant polymer composites. Additionally, the most widely used flammability measuring techniques for polymeric composites are presented. Finally, the key factors and different methods that are used for property enhancement are concluded and the scope for future work is discussed.

  • 117.
    Badria, Adel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Click Chemistry: A Promising Tool for Building Hierarchical Structures2022In: Polymers, E-ISSN 2073-4360, Vol. 14, no 19, article id 4077Article, review/survey (Refereed)
    Abstract [en]

    The hierarchical structures are utilized at different levels in nature. Moreover, a wide spectrum of nature’s properties (e.g., mechanical, physical and biological properties) has been attributed to this hierarchy. Different reviews have been published to cover the use of click chemistry in building hierarchical structures. However, each one of those reviews focused on a narrow area on this topic, i.e., specific chemical reaction, such as in thiol-ene chemistry, or a specific molecule or compound such as polyhedral oligomeric silsesquioxane, or a certain range of hierarchical structures between the nano to micro range, e.g., nanocrystals. In this review, a frame to connect the dots between the different published works has been demonstrated. This article will not attempt to give an exhaustive review of all the published work in the field, instead the potential of click chemistry to build hierarchical structures of different levels using building blocks of different length scales has been shown through two main approaches. The first is a one-step direct formation of 3D micro/macrometer dimensions structures from Pico dimensions structures (molecules, monomers, etc.). The second approach includes several steps Pico ➔ 0D nano ➔ 1D nano ➔ 2D nano ➔ 3D nano/micro/macro dimensions structures. Another purpose of this review article is to connect between (a) the atomic theory, which covers the atoms and molecules in the picometer dimensions (picoscopic chemistry set); (b) “nano-periodic system” model, which covers different nanobuilding blocks in the nanometers range such as nanoparticles, dendrimers, buckyball, etc. which was developed by Tomalia; and (c) the micro/macrometer dimensions level.

  • 118.
    Badria, Adel
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Hutchinson, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Sanz del Olmo, Natalia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Malkoch, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Acrylate-free tough 3D printable thiol-ene thermosets and composites for biomedical applications2022In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 139, no 43, article id e53046Article in journal (Refereed)
    Abstract [en]

    Polymer thermosets and composites based on rigid trizaine-trione (TATO) alkene and thiol monomers show great promise as bone fixation materials and dental composites due to their ability to efficiently crosslink via thiol-ene coupling chemistry into stiff and strong materials. In order to broaden the scope of these materials, a TATO thermoset was optimized for sterolithography (SLA) 3D printing through the addition of either a diluent (PETMP) and photo-absorber (Sudan I), or the addition of a free radical inhibitor (pyrogallol). A 3D printable hydroxyapatite (HA) composite was also formulated by adding a combination of nano-HA and micro-HA particles, which were found to increase the thermal stability and modulus of the material, respectively. The modulus of the printed thermosets containing Sudan I and pyrogallol exceeded any previously published acrylate-free thiol-ene SLA resins, at 1.6 (0.1) and 1.85 (0.06) GPa, respectively. The printed HA composite formulation had a modulus of 2.4 (0.2) GPa. All three formulations showed a comparable resolution to a commercially available SLA resin and were non-toxic toward Raw 264.7 and human dermal fibroblast cells. These results demonstrate the potential of TATO based SLA resins for the construction of strong, fully-customizable, printed implants for biomedical applications.

  • 119.
    Badria, Adel
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. Univ Patras, Dept Mech Engn & Aeronaut, Div Appl Mech Technol Mat & Biomech, Patras, Greece..
    Koutsoukos, Petros G.
    Univ Patras, Dept Chem Engn, Patras Univ Campus, Patras 26504, Greece..
    Mavrilas, Dimosthenis
    Univ Patras, Dept Mech Engn & Aeronaut, Div Appl Mech Technol Mat & Biomech, Patras, Greece..
    Decellularized tissue-engineered heart valves calcification: what do animal and clinical studies tell us?2020In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 31, no 12, article id 132Article in journal (Refereed)
    Abstract [en]

    Cardiovascular diseases are the first cause of death worldwide. Among different heart malfunctions, heart valve failure due to calcification is still a challenging problem. While drug-dependent treatment for the early stage calcification could slow down its progression, heart valve replacement is inevitable in the late stages. Currently, heart valve replacements involve mainly two types of substitutes: mechanical and biological heart valves. Despite their significant advantages in restoring the cardiac function, both types of valves suffered from serious drawbacks in the long term. On the one hand, the mechanical one showed non-physiological hemodynamics and the need for the chronic anticoagulation therapy. On the other hand, the biological one showed stenosis and/or regurgitation due to calcification. Nowadays, new promising heart valve substitutes have emerged, known as decellularized tissue-engineered heart valves (dTEHV). Decellularized tissues of different types have been widely tested in bioprosthetic and tissue-engineered valves because of their superior biomechanics, biocompatibility, and biomimetic material composition. Such advantages allow successful cell attachment, growth and function leading finally to a living regenerative valvular tissue in vivo. Yet, there are no comprehensive studies that are covering the performance of dTEHV scaffolds in terms of their efficiency for the calcification problem. In this review article, we sought to answer the question of whether decellularized heart valves calcify or not. Also, which factors make them calcify and which ones lower and/or prevent their calcification. In addition, the review discussed the possible mechanisms for dTEHV calcification in comparison to the calcification in the native and bioprosthetic heart valves. For this purpose, we did a retrospective study for all the published work of decellularized heart valves. Only animal and clinical studies were included in this review. Those animal and clinical studies were further subcategorized into 4 categories for each depending on the effect of decellularization on calcification. Due to the complex nature of calcification in heart valves, other in vitro and in silico studies were not included. Finally, we compared the different results and summed up all the solid findings of whether decellularized heart valves calcify or not. Based on our review, the selection of the proper heart valve tissue sources (no immunological provoking residues), decellularization technique (no damaged exposed residues of the decellularized tissues, no remnants of dead cells, no remnants of decellularizing agents) and implantation techniques (avoiding suturing during the surgical implantation) could provide a perfect anticalcification potential even without in vitro cell seeding or additional scaffold treatment. [GRAPHICS] .

  • 120. Bandekar, R.
    et al.
    Oldmark, A.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kallen, L.
    Liedberg, J.
    Foan, J.
    Wearing, J.
    Cross flow filtration of green liquor for increased pulp production, improved green liquor quality, and energy savings2020In: PEERS/IBBC Virtual Conference 2020, TAPPI Press , 2020, p. 336-349Conference paper (Refereed)
    Abstract [en]

    A new green liquor filtration system has been installed and commissioned at the Ence pulp mill in Pontevedra, Spain. The filtration system is based on microfiltration and was developed in collaboration with the KTH Royal Institute of Technology in Stockholm, Sweden. The patented method for efficient purification of green liquor decreases the NPE content by providing more efficient solids/liquid separation, reducing energy and chemical consumption in pulp mills, and could lead to increased production capacity by eliminating certain capacity bottlenecks. The process has been tested at the Aspa Bruk Mill outside Askersund Sweden continuously since 2013. The technology has proven to create nearly particulate free green liquor during the purification process. The technology can also be used to polish white liquor to provide higher pulp quality. To provide for a simple cost-effective installation, the system was designed as a skid mounted unit pre-piped, instrumented, and tested before shipment. The system is modular and allows for easy expansion of capacity. This paper discusses the process design, process integration, and startup of the new system, along with experiences for the first months of operation.

  • 121.
    Bandekar, R.
    et al.
    NORAM Engn & Constructors Ltd, Pulp & Paper, Vancouver, BC, Canada.
    Oldmark, A.
    BillerudKorsnäs AB, Solna, Sweden.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kallen, L.
    CleanFlow BLACK AB, Forshaga, Sweden.
    Liedberg, J.
    NORAM Int AB, Gothenburg, Sweden.
    Foan, J.
    NORAM Engn & Constructors Ltd, Pulp & Paper, Vancouver, BC, Canada.
    Wearing, J.
    NORAM Engn & Constructors Ltd, Pulp & Paper, Vancouver, BC, Canada.
    Crossflow filtration of green liquor for increased pulp production, improved green liquor quality, and energy savings2020In: TAPPI Journal, ISSN 0734-1415, Vol. 19, no 10, p. 527-538Article in journal (Refereed)
    Abstract [en]

    A new green liquor filtration system has been installed and commissioned at the Ence pulp mill in Pontevedra, Spain. The filtration system is based on microfiltration and was developed in collaboration with the KTH Royal Institute of Technology in Stockholm, Sweden. The patented method for efficient purification of green liquor decreases the non-process element (NPE) content by providing more efficient solids/liquid separation, reducing energy and chemical consumption in pulp mills and increasing production capacity by eliminating certain capacity bottlenecks. The process has been continuously tested at the Aspa Bruk Mill outside Askersund, Sweden, since 2013. The technology has proven to create nearly particulate-free green liquor during the purification process. The technology can also be used to polish white liquor to provide higher pulp quality. To provide for a simple and cost-effective installation, the system was designed as a skid-mounted unit that is pre-piped, instrumented, and tested before shipment. The system is modular and allows for easy expansion of capacity. This paper discusses the process design, process integration, and startup of the new system, along with experi-ences from the first months of operation. Application: The patented and trademarked CleanFlow system is a technology designed to increase the capacity of a kraft mill recausticizing plant. Crossflow ceramic membranes are used to filter a portion of the green liquor, debottlenecking the existing green liquor clarifiers’ filters. The liquor quality is improved by reducing the buildup of NPEs. CleanFlow can also be implemented to filter white liquor, either the entire stream for improved pulp quality or just a portion, such as with preparing oxidized white liquor for pulp delignification after cooking, or for scrubbing of bleaching system vents.

  • 122.
    Becerra Garcia, Marley
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Aljure, Mauricio
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. BioGRID Grupo de Investigación y Desarrollo en Ciencias, Tecnología e Innovación, SoPhiC Sociedad de Doctores e Investigadores de Colombia, Bogotá, Colombia.
    Pourrahimi, Amir Masoud
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
    Roman, F.
    High field conduction in mineral oil based zno nanofluids prior to negative streamer inception2021In: Journal of Physics Communications, ISSN 2399-6528, Vol. 5, no 4, article id 045006Article in journal (Refereed)
    Abstract [en]

    The electric conduction under intense electric fields (up to ∼ 109 V/m) in nanofluids using surface-modified ZnO–C18 nanoparticles dispersed in mineral oil as host, is investigated with both experiments and numerical simulations. The measurements are used to estimate unknown parameters necessary to represent the generation and loss of electrons in an electrohydrodynamic model for mineral oil with and without ZnO–C18 nanoparticles in a needle-plane configuration. The model suggests that ZnO–C18 nanoparticles induce an enhanced field emission from negative needles, explaining the significantly larger conduction currents measured in the nanofluid compared with those in the host liquid. It is also found that the scavenging of electrons by ZnO–C18 nanoparticles is a process which is negligible compared with the loss of electrons due to attachment in mineral oil. It is shown that ZnO–C18 nanoparticles hinder the streamer initiation process by reducing the effective electric field at the tip of the needle. This electric field reduction is caused by the combined effect of enhanced electron injection through ZnO–C18 nanoparticles and strong electron attachment in mineral oil. Thus, the electric field on the needle tip reaches the same threshold value when the streamer is incepted in the nanofluid as in mineral oil, although at a larger voltage. Solid evidence indicating that the additional electron scavenging and the reduced electron mobility introduced by nanoparticles has no effect in the conduction currents and in the negative streamer inception in the tested ZnO–C18 nanofluids is shown.

  • 123.
    Behroozi Kohlan, Taha
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye.
    Atespare, Asu Ece
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Yildiz, Mehmet
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Menceloglu, Yusuf Ziya
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Unal, Serkan
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Dizman, Bekir
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Amphiphilic Polyoxazoline Copolymer-Imidazole Complexes as Tailorable Thermal Latent Curing Agents for One-Component Epoxy Resins2023In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 49, p. 47173-47186Article in journal (Refereed)
    Abstract [en]

    One-component epoxy resins (OCERs) are proposed to overcome the energy inefficiency and processing difficulties of conventional two-component epoxy resins by employing latent curing agents, specifically thermal latent curing agents (TLCs). Despite recent progress, the need for TLCs with a simple preparation method for different curing agents, epoxy resins, and process conditions remains. Here, tailorable TLCs were prepared by forming complexes between imidazole (Im) and amphiphilic polyoxazoline copolymers with tunable structures and properties by a solvent evaporation method. The obtained TLCs were manually mixed with DGEBA to prepare OCERs. The miscibility of the complexes with DGEBA was studied, considering the functionalities of copolymers. The curing behaviors of TLCs were compared using dynamic Differential Scanning Calorimetry (DSC) studies considering the side chain and composition of the copolymers, copolymer:Im ratio, and concentration of Im in DGEBA. The curing behavior of the promising OCERs was studied by isothermal DSC studies to investigate their stability at different temperatures and curing rate at elevated temperatures revealing the stability of these OCERs.

  • 124.
    Behroozi Kohlan, Taha
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Wen, Yanru
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mini, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Schiff base crosslinked hyaluronic acid hydrogels with tunable and cell instructive time-dependent mechanical properties2024In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 338, article id 122173Article in journal (Refereed)
    Abstract [en]

    The dynamic interplay between cells and their native extracellular matrix (ECM) influences cellular behavior, imposing a challenge in biomaterial design. Dynamic covalent hydrogels are viscoelastic and show self-healing ability, making them a potential scaffold for recapitulating native ECM properties. We aimed to implement kinetically and thermodynamically distinct crosslinkers to prepare self-healing dynamic hydrogels to explore the arising properties and their effects on cellular behavior. To do so, aldehyde-substituted hyaluronic acid (HA) was synthesized to generate imine, hydrazone, and oxime crosslinked dynamic covalent hydrogels. Differences in equilibrium constants of these bonds yielded distinct properties including stiffness, stress relaxation, and self-healing ability. The effects of degree of substitution (DS), polymer concentration, crosslinker to aldehyde ratio, and crosslinker functionality on hydrogel properties were evaluated. The self-healing ability of hydrogels was investigated on samples of the same and different crosslinkers and DS to obtain hydrogels with gradient properties. Subsequently, human dermal fibroblasts were cultured in 2D and 3D to assess the cellular response considering the dynamic properties of the hydrogels. Moreover, assessing cell spreading and morphology on hydrogels having similar modulus but different stress relaxation rates showed the effects of matrix viscoelasticity with higher cell spreading in slower relaxing hydrogels.

  • 125.
    Belaineh, Dagmawi
    et al.
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden.;RISE Acreo, RISE Res Inst Sweden, Div ICT, S-60117 Norrkoping, Sweden..
    Andreasen, Jens W.
    Tech Univ Denmark, Dept Energy Convers & Storage, DK-4000 Roskilde, Denmark..
    Palisaitis, Justinas
    Linkoping Univ, Dept Phys Chem & Biol, S-58183 Linkoping, Sweden..
    Malti, Abdellah
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hakansson, Karl
    RISE Bioecon, Res Inst Sweden, S-11486 Stockholm, Sweden..
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Crispin, Xavier
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden..
    Engquist, Isak
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden..
    Berggren, Magnus
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden..
    Controlling the Organization of PEDOT:PSS on Cellulose Structures2019In: ACS APPLIED POLYMER MATERIALS, ISSN 2637-6105, Vol. 1, no 9, p. 2342-2351Article in journal (Refereed)
    Abstract [en]

    Composites of biopolymers and conducting polymers are emerging as promising candidates for a green technological future and are actively being explored in various applications, such as in energy storage, bioelectronics, and thermoelectrics. While the device characteristics of these composites have been actively investigated, there is limited knowledge concerning the fundamental intracomponent interactions and the modes of molecular structuring. Here, by use of cellulose and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it is shown that the chemical and structural makeup of the surfaces of the composite components are critical factors that determine the materials organization at relevant dimensions. AFM, TEM, and GIVVAXS measurements show that when mixed with cellulose nanofibrils, PEDOT:PSS organizes into continuous nanosized beadlike structures with an average diameter of 13 nm on the nanofibrils. In contrast, when PEDOT:PSS is blended with molecular cellulose, a phase-segregated conducting network morphology is reached, with a distinctly relatively lower electric conductivity. These results provide insight into the mechanisms of PEDOT:PSS crystallization and may have significant implications for the design of conducting biopolymer composites for a vast array of applications.

  • 126.
    Belioka, Maria-Paraskeui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Exploration of surface cleaning and surface interactions via atomic force microscopy2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 127. Benedikt Maria Köhnlein, M.
    et al.
    Abitbol, T.
    Osório Oliveira, A.
    Magnusson, M. S.
    Adolfsson, Karin H.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Svensson, S. E.
    Ferreira, J. A.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Zamani, A.
    Bioconversion of food waste to biocompatible wet-laid fungal films2022In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 216, p. 110534-, article id 110534Article in journal (Refereed)
    Abstract [en]

    The fungus Rhizopus delemar was grown on bread waste in a submerged cultivation process and wet-laid into films. Alkali or enzyme treatments were used to isolate the fungal cell wall. A heat treatment was also applied to deactivate biological activity of the fungus. Homogenization of fungal biomass was done by an iterative ultrafine grinding process. Finally, the biomass was cast into films by a wet-laid process. Ultrafine grinding resulted in densification of the films. Fungal films showed tensile strengths of up to 18.1 MPa, a Young's modulus of 2.3 GPa and a strain at break of 1.4%. Highest tensile strength was achieved using alkali treatment, with SEM analysis showing a dense and highly organized structure. In contrast, less organized structures were obtained using enzymatic or heat treatments. A cell viability assay and fluorescent staining confirmed the biocompatibility of the films. A promising route for food waste valorization to sustainable fungal wet-laid films was established.

  • 128.
    Bengtsson, Andreas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. RISE Research Institutes of Sweden AB.
    Biobased carbon fibers from solution spun lignocellulosic precursors2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbon fibers (CFs) have excellent mechanical properties and a low density, making themattractive as a reinforcing fiber in composites. The use of CFs is limited to high-end applications,since they are produced from an expensive fossil-based precursor via an energy-intensivemanufacturing process, explaining the need for cheaper CFs from renewables. CFs can be madefrom strong cellulosic precursors, but the low carbon content of cellulose results in a lowconversion yield, and thus an expensive CF. Lignin has a higher carbon content than cellulose butCFs from melt spun lignin precursors have presented challenges, since these precursors have a lowstrength and are difficult to convert to CF in a realistic conversion time.In the present work, CFs from solution spun precursors consisting of blends of softwood kraftlignin and cellulose have been developed. The lignin-cellulose precursors (up to 70% lignin) wereprepared with air-gap spinning and wet spinning, using an ionic liquid and a water-based solventsystem for co-dissolution, respectively. Co-processing of cellulose and lignin was beneficial as theformer made the precursor strong and easy to handle, whereas the latter gave a higher conversionyield than precursors based solely on cellulose. The precursors were converted to CFs via bothbatchwise and continuous conversion, using industrially relevant times (< 2 h), with a yield up to45 wt% after incorporation of a flame retardant.These CFs have a moderate Young’s modulus and tensile strength up to 75–77 GPa and 1.2 GPa,respectively, i.e. similar to the values for CFs from fossil-based isotropic pitch and they can thusbe classified as general-grade CFs. These biobased CFs have a disordered turbostratic graphitestructure, and their tensile properties are affected by the precursor structure, the conversionconditions, and the final diameter. These CFs can potentially be used as a sustainable componentin non-structural and semi-structural applications.

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    Thesis
  • 129.
    Bengtsson, Andreas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Carbon fibres from lignin-cellulose precursors2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is in the nature of the human species to find solutions of complex technical problems and always strive for improvements. The development of new materials is not an exception. One of the many man-made materials is carbon fibre (CF). Its excellent mechanical properties and low density have made it attractive as the reinforcing agent in lightweight composites. However, the high price of CF originating from expensive production is currently limiting CF from wider utilisation, e.g. in the automotive sector.

     

    The dominating raw material used in CF production is petroleum-based polyacrylonitrile (PAN). The usage of fossil-based precursors and the high price of CF explain the strong driving force of finding cheaper and renewable alternatives. Lignin and cellulose are renewable macromolecules available in high quantities. The high carbon content of lignin is an excellent property, while its structural heterogeneity yields in CF with poor mechanical properties. In contrast, cellulose has a beneficial molecular orientation, while its low carbon content gives a low processing yield and thus elevates processing costs.

     

    This work shows that several challenges associated with CF processing of each macromolecule can be mastered by co-processing. Dry-jet wet spun precursor fibres (PFs) made of blends of softwood kraft lignin and kraft pulps were converted into CF. The corresponding CFs demonstrated significant improvement in processing yield with negligible loss in mechanical properties relative to cellulose-derived CFs. Unfractionated softwood kraft lignin and paper grade kraft pulp performed as good as more expensive retentate lignins and dissolving grade kraft pulp, which is beneficial from an economic point of view.

     

    The stabilisation stage is considered the most time-consuming step in CF manufacturing. Here it was shown that the PFs could be oxidatively stabilised in less than 2 h or instantly carbonised without any fibre fusion, suggesting a time-efficient processing route. It was demonstrated that PF impregnation with ammonium dihydrogen phosphate significantly improves the yield but at the expense of mechanical properties.

     

    A reduction in fibre diameter was beneficial for the mechanical properties of the CFs made from unfractionated softwood kraft lignin and paper grade kraft pulp. Short oxidative stabilisation (<2 h) of thin PFs ultimately provided CFs with tensile modulus and strength of 76 GPa and 1070 MPa, respectively. Considering the high yield (39 wt%), short stabilisation time and promising mechanical properties, the concept of preparing CF from lignin:cellulose blends is a very promising route.

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    Carbon fibres from lignin-cellulose precursors
  • 130.
    Bengtsson, Andreas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Division Bioeconomy and Health, RISE Research Institutes of Sweden, P.O. Box 5604, SE-114 86 Stockholm, Sweden.
    Carbon fibres from wet spun cellulose-ligninprecursors using the cold alkali processManuscript (preprint) (Other academic)
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    fulltext
  • 131.
    Bengtsson, Andreas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Bengtsson, Jenny
    Swerea IVF, Box 104, SE-43122 Molndal, Sweden..
    Olsson, Carina
    Swerea IVF, Box 104, SE-43122 Molndal, Sweden..
    Sedin, Maria
    RISE Innventia, Box 5604, SE-11486 Stockholm, Sweden..
    Jedvert, Kerstin
    Swerea IVF, Box 104, SE-43122 Molndal, Sweden..
    Theliander, Hans
    Chalmers Univ Technol, SE-41296 Gothenburg, Sweden..
    Sjoholm, Elisabeth
    RISE Innventia, Box 5604, SE-11486 Stockholm, Sweden..
    Improved yield of carbon fibres from cellulose and kraft lignin2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 12, p. 1007-1016Article in journal (Refereed)
    Abstract [en]

    To meet the demand for carbon-fibre-reinforced composites in lightweight applications, cost-efficient processing and new raw materials are sought for. Cellulose and kraft lignin are each interesting renewables for this purpose due to their high availability. The molecular order of cellulose is an excellent property, as is the high carbon content of lignin. By co-processing cellulose and lignin, the advantages of these macromolecules are synergistic for producing carbon fibre (CF) of commercial grade in high yields. CFs were prepared from precursor fibres (PFs) made from 70: 30 blends of softwood kraft lignin (SW-KL) and cellulose by dry-jet wet spinning with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) as a solvent. In focus was the impact of the molecular mass of lignin and the type of cellulose source on the CF yield and properties, while membrane-filtrated kraft lignin and cellulose from dissolving kraft pulp and fully bleached paper-grade SW-KP (kraft pulp) served as sources. Under the investigated conditions, the yield increased from around 22% for CF from neat cellulose to about 40% in the presence of lignin, irrespective of the type of SW-KL. The yield increment was also higher relative to the theoretical one for CF made from blends (69%) compared to those made from neat celluloses (48-51%). No difference in the mechanical properties of the produced CF was observed.

  • 132.
    Bengtsson, Andreas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Bengtsson, Jenny
    RISE Mat & Prod, Box 104, SE-43122 Molndal, Sweden..
    Sedin, Maria
    RISE Bioecon, Box 5604, SE-11486 Stockholm, Sweden..
    Sjoholm, Elisabeth
    RISE Bioecon, Box 5604, SE-11486 Stockholm, Sweden..
    Carbon Fibers from Lignin-Cellulose Precursors: Effect of Stabilization Conditions2019In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, no 9, p. 8440-8448Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for lightweight composites reinforced with carbon fibers (CFs). Due to its high availability and carbon content, kraft lignin has gained attention as a potential low-cost CF precursor. CFs with promising properties can be made from flexible dry-jet wet spun precursor fibers (PFs) from blends (70:30) of softwood kraft lignin and fully bleached softwood kraft pulp. This study focused on reducing the stabilization time, which is critical in CF manufacturing. The impact of stabilization conditions on chemical structure, yield, and mechanical properties was investigated. It was possible to reduce the oxidative stabilization time of the PFs from about 16 h to less than 2 h, or even omitting the stabilization step, without fusion of fibers. The main reactions involved in the stabilization stage were dehydration and oxidation. The results suggest that the isothermal stabilization at 250 degrees C override the importance of having a slow heating rate. For CFs with a commercial diameter, stabilization of less than 2 h rendered in tensile modulus 76 GPa and tensile strength 1070 MPa. Impregnation with ammonium dihydrogen phosphate significantly increased the CF yield, from 31-38 to 46-50 wt %, but at the expense of the mechanical properties.

  • 133.
    Bengtsson, Andreas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Bengtsson, Jenny
    Sedin, Maria
    Sjöholm, Elisabeth
    Carbon fibres from lignin-cellulose precursors: Effect of stabilisation conditionsManuscript (preprint) (Other academic)
  • 134.
    Bengtsson, Andreas
    et al.
    RISE .
    Hecht, P.
    RISE.
    Sommertune, J.
    RISE.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sedin, M.
    RISE.
    Sjöholm, E.
    RISE.
    Carbon Fibers from Lignin-Cellulose Precursors: Effect of Carbonization Conditions2020In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 8, no 17, p. 6826-6833Article in journal (Refereed)
    Abstract [en]

    Carbon fibers (CFs) are gaining increasing importance in lightweight composites, but their high price and reliance on fossil-based raw materials stress the need for renewable and cost-efficient alternatives. Kraft lignin and cellulose are renewable macromolecules available in high quantities, making them interesting candidates for CF production. Dry-jet wet spun precursor fibers (PFs) from a 70/30 w/w blend of softwood kraft lignin (SKL) and fully bleached softwood kraft pulp (KP) were converted into CFs under fixation. The focus was to investigate the effect of carbonization temperature and time on the CF structure and properties. Reducing the carbonization time from 708 to 24 min had no significant impact on the tensile properties. Increasing the carbonization temperature from 600 to 800 °C resulted in a large increase in the carbon content and tensile properties, suggesting that this is a critical region during carbonization of SKL:KP PFs. The highest Young's modulus (77 GPa) was obtained after carbonization at 1600 °C, explained by the gradual transition from amorphous to nanocrystalline graphite observed by Raman spectroscopy. On the other hand, the highest tensile strength (1050 MPa) was achieved at 1000 °C, a decrease being observed thereafter, which may be explained by an increase in radial heterogeneity.

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  • 135.
    Bengtsson, Andreas
    et al.
    RISE Res Inst Sweden, Div Bioecon & Hlth, Mat & Surface Design, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Landmer, Alice
    RISE Res Inst Sweden, Div Bioecon & Hlth, Mat & Surface Design, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Norberg, Lars
    RISE Res Inst Sweden, Div Bioecon & Hlth, Mat & Surface Design, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Yu, Shun
    RISE Res Inst Sweden, Div Bioecon & Hlth, Mat & Surface Design, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Brännvall, Elisabet
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Engineering Pedagogics.
    Sedin, Maria
    RISE Res Inst Sweden, Div Bioecon & Hlth, Mat & Surface Design, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Carbon Fibers from Wet-Spun Cellulose-Lignin Precursors Using the Cold Alkali Process2022In: FIBERS, ISSN 2079-6439, Vol. 10, no 12, article id 108Article in journal (Refereed)
    Abstract [en]

    In recent years, there has been extensive research into the development of cheaper and more sustainable carbon fiber (CF) precursors, and air-gap-spun cellulose-lignin precursors have gained considerable attention where ionic liquids have been used for the co-dissolution of cellulose and lignin. However, ionic liquids are expensive and difficult to recycle. In the present work, an aqueous solvent system, cold alkali, was used to prepare cellulose-lignin CF precursors by wet spinning solutions containing co-dissolved dissolving-grade kraft pulp and softwood kraft lignin. Precursors containing up to 30 wt% lignin were successfully spun using two different coagulation bath compositions, where one of them introduced a flame retardant into the precursor to increase the CF conversion yield. The precursors were converted to CFs via batchwise and continuous conversion. The precursor and conversion conditions had a significant effect on the conversion yield (12-44 wt%), the Young's modulus (33-77 GPa), and the tensile strength (0.48-1.17 GPa), while the precursor morphology was preserved. Structural characterization of the precursors and CFs showed that a more oriented and crystalline precursor gave a more ordered CF structure with higher tensile properties. The continuous conversion trials highlighted the importance of tension control to increase the mechanical properties of the CFs.

  • 136.
    Benselfelt, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Design of Cellulose-based Materials by Supramolecular Assemblies2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to climate change and plastic pollution, there is an increasing demand for bio-based materials with similar properties to those of common plastics yet biodegradable. In this respect, cellulose is a strong candidate that is already being refined on a large industrial scale, but the properties differ significantly from those of common plastics in terms of shapeability and water-resilience.

    This thesis investigates how supramolecular interactions can be used to tailor the properties of cellulose-based materials by modifying cellulose surfaces or control the assembly of cellulose nanofibrils (CNFs). Most of the work is a fundamental study on interactions in aqueous environments, but some material concepts are presented and potential applications are discussed.

    The first part deals with the modification of cellulose by the spontaneous adsorption of xyloglucan or polyelectrolytes. The results indicate that xyloglucan adsorbs to cellulose due to the increased entropy of water released from the surfaces, which is similar to the increased entropy of released counter-ions that drives polyelectrolyte adsorption. The polyelectrolyte adsorption depends on the charge of the cellulose up to a limit after which the charge density affects only the first adsorbed layer in a multilayer formation.

    Latex nanoparticles with polyelectrolyte coronas can be adsorbed onto cellulose in order to prepare hydrophobic cellulose surfaces with strong and ductile wet adhesion, provided the glass transition of the core is below the ambient temperature.

    The second part of the thesis seeks to explain the interactions between different types of cellulose nanofibrils in the presence of different ions, using a model consisting of ion-ion correlation and specific ion effects, which can be employed to rationally design water-resilient and transparent nanocellulose films. The addition of small amounts of alginate also creates interpenetrating double networks, and these networks lead to a synergy which improves both the stiffness and the ductility of the films in water.

    A network model has been developed to understand these materials, with the aim to explain the properties of fibril networks, based on parameters such as the aspect ratio of the fibrils, the solidity of the network, and the ion-induced interactions that increase the friction between fibrils. With the help of this network model and the model for ion-induced interactions, we have created films with wet-strengths surpassing those of common plastics, or a ductility suitable for hygroplastic forming into water-resilient and biodegradable packages. Due to their transparency, water content, and the biocompatibility of cellulose, these materials are also suitable for biomaterial or bioelectronics applications. 

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  • 137.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore, Singapore.
    Kummer, Nico
    Laboratory for Cellulose & Wood Materials, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland, Überlandstrasse 129; Department of Health Sciences and Technology, ETH Zürich, 8092, Zürich, Switzerland.
    Nordenström, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fall, Andreas B.
    RISE Bioeconomy, 114 28, Stockholm, Sweden.
    Nyström, Gustav
    Laboratory for Cellulose & Wood Materials, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland, Überlandstrasse 129; Department of Health Sciences and Technology, ETH Zürich, 8092, Zürich, Switzerland.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    The Colloidal Properties of Nanocellulose2023In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, ChemSusChem, ISSN 1864-5631, Vol. 16, no 8, article id e202201955Article, review/survey (Refereed)
    Abstract [en]

    Nanocelluloses are anisotropic nanoparticles of semicrystalline assemblies of glucan polymers. They have great potential as renewable building blocks in the materials platform of a more sustainable society. As a result, the research on nanocellulose has grown exponentially over the last decades. To fully utilize the properties of nanocelluloses, a fundamental understanding of their colloidal behavior is necessary. As elongated particles with dimensions in a critical nanosize range, their colloidal properties are complex, with several behaviors not covered by classical theories. In this comprehensive Review, we describe the most prominent colloidal behaviors of nanocellulose by combining experimental data and theoretical descriptions. We discuss the preparation and characterization of nanocellulose dispersions, how they form networks at low concentrations, how classical theories cannot describe their behavior, and how they interact with other colloids. We then show examples of how scientists can use this fundamental knowledge to control the assembly of nanocellulose into new materials with exceptional properties. We hope aspiring and established researchers will use this Review as a guide.

  • 138.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Nordenström, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hamedi, Mahiar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ion-induced assemblies of highly anisotropic nanoparticles are governed by ion-ion correlation and specific ion effects2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 8, p. 3514-3520Article in journal (Refereed)
    Abstract [en]

    Ion-induced assemblies of highly anisotropic nanoparticles can be explained by a model consisting of ion-ion correlation and specific ion effects: dispersion interactions, metal-ligand complexes, and local acidic environments. Films of cellulose nanofibrils and montmorillonite clay were treated with different ions, and their subsequent equilibrium swelling in water was related to important parameters of the model in order to investigate the relative importance of the mechanisms. Ion-ion correlation was shown to be the fundamental attraction, supplemented by dispersion interaction for polarizable ions such as Ca2+ and Ba2+, or metal-ligand complexes for ions such as Cu2+, Al3+ and Fe3+. Ions that form strong complexes induce local acidic environments that also contribute to the assembly. These findings are summarized in a comprehensive semi-quantitative model and are important for the design of nanomaterials and for understanding biological systems where specific ions are involved.

  • 139.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Nordenström, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Lindstrom, Stefan B.
    Linkoping Univ, Div Solid Mech, Dept Management & Engn, S-58183 Linkoping, Sweden..
    Wågberg, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH Royal Inst Technol, Div Fibre Technol, Dept Fiber & Polymer Technol, Tekn Ringen 56-58, S-10044 Stockholm, Sweden.;KTH Royal Inst Technol, Wallenberg Wood Sci Ctr, Dept Fiber & Polymer Technol, Tekn Ringen 56-58, S-10044 Stockholm, Sweden..
    Explaining the Exceptional Wet Integrity of Transparent Cellulose Nanofibril Films in the Presence of Multivalent Ions-Suitable Substrates for Biointerfaces2019In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, no 13, article id 1900333Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNFs) assemble into water-resilient materials in the presence of multivalent counter-ions. The essential mechanisms behind these assemblies are ion-ion correlation and specific ion effects. A network model shows that the interfibril attraction indirectly influences the wet modulus by a fourth power relationship to the solidity of the network (E-w proportional to phi(4)). Ions that induce both ion-ion correlation and specific ion effects significantly reduce the swelling of the films, and due to the nonlinear relationship dramatically increase the wet modulus. Herein, this network model is used to explain the elastoplastic behavior of wet films of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized, carboxymethylated, and phosphorylated CNFs in the presence of different counter-ions. The main findings are that the aspect ratio of the CNFs influences the ductility of the assemblies, that the bivalency of phosphorylate ligands probably limits the formation of interfibril complexes with divalent ions, and that a higher charge density increases the friction between fibrils by increasing the short-range attraction from ion-ion correlation and specific ion effects. These findings can be used to rationally design CNF materials for a variety of applications where wet strength, ductility, and transparency are important, such as biomaterials or substrates for bioelectronics.

  • 140.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Nordenström, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lindström, Stefan
    Linköping University.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Explaining the exceptional wet integrity of transparent cellulose nanofibril films in the presence of multivalent ions - Suitable substrates for biointerfacesManuscript (preprint) (Other academic)
  • 141.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Dynamic networks of cellulose nanofibrils as a platform for tunable hydrogels, aerogels, and chemical modifications2018In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 142.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Unidirectional Swelling of Dynamic Cellulose Nanofibril Networks: A Platform for Tunable Hydrogels and Aerogels with 3D Shapeability2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 6, p. 2406-2412Article in journal (Refereed)
    Abstract [en]

    A process has been developed to create self-supporting hydrogels with low solids content (down to 0.5 wt %) and anisotropic aerogels with a low density (down to 5 kg/m(3)) from cellulose nanofibrils (CNFs). The CNF networks were formed by vacuum filtration of dilute dispersions (0.2 wt %) of 90% CNFs and 10% alginate. We call this process "the dynamic CNF network approach" since the solids content of these hydrogels can be tuned in the range of 0.5-3 wt % by reswelling the filter cakes in a medium with a controlled osmotic pressure. These hydrogels are significantly stronger than the 1-2 wt % CNF gels typically used to prepare hydrogels and aerogels because the dynamic CNF networks are formed below their arrested state threshold (ca. 0.5 wt %) and are thus homogeneous. The vacuum filtration leads to a directional reswelling vertical to the plane of the filter cake, and this is crucial in order to turn a two-dimensional (2D) shape, cut from the filter cake, into a 3D hydrogel without distorting the 2D shape. The anisotropic swelling was used to create intricate 3D-shaped hydrogels and solved some of the issues involved in the degassing and molding of high-viscosity CNF gels. Multivalent ions were used to lock the CNF and alginate networks at the desired solids content and 3D shape, and resulted in an increase by an order of magnitude in storage modulus. Moreover, the self-supporting nature of the hydrogels allowed us to freeze-cast them into anisotropic aerogels with the same 3D shape without using any container. The 5 kg/m(3) aerogel had a specific modulus of 43 kN m/kg and an anisotropy index of 12, which are impressive properties in relation to earlier experiences. The process can be used for applications where a precise control of density and shape is critical.

  • 143.
    Benyahia Erdal, Nejla
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Cellulose derived carbon dots: From synthesis to evaluation as multifunctional building blocks in biomedical scaffolds2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The implementation of biobased and biodegradable polymeric materials in biomedical applications is often coupled with issues related to their insufficient mechanical properties or limited bioactivity. In this thesis, a perspective on valorization of biomass is presented, demonstrating the transformation of cellulose into biobased carbon nanomaterials with the potential to serve as multifunctional property enhancers in polycaprolactone (PCL) scaffold materials for tissue engineering.

    Firstly, nanographene oxide (nGO) type of carbon dots were produced through a microwave assisted hydrothermal carbonization of cellulose and subsequent oxidation in an acidic environment. The carbon dots demonstrated zero-dimensional (0D) character, ample amount of oxygen functionalities and fluorescence properties. Furthermore, a green reduction process in superheated water was developed to reduce the nGO carbon dots with and without the aid of a green reducing agent, caffeic acid (CA). The resulting r-nGO and r-nGO-CA showed in contrast to nGO decreased oxygen content and enhanced thermal stability. r-nGO-CA, in addition, maintained good cell viability towards osteoblast-like cells at a higher concentration than nGO.

    Secondly, incorporation of r-nGO or r-nGO-CA in PCL nanocomposites induced great enhancement in mineralization capability and creep resistance. nGO carbon dots could also due to their oxygen-rich content, be utilized to modify 3D scaffolds through surface functionalization and blending. The nGO on the surface of the PCL scaffolds, produced through optimized solvent casting particulate leaching (SCPL) techniques, could act as anchor sites for antibiotic loading and induce mineralization. It was also shown that incorporation of nGO in PCL scaffolds fabricated through high internal phase emulsion (HIPE) templating influenced the macrostructure of the scaffolds further manifesting the versatility and potential of the fabricated biobased carbon dots in biomedical applications.

  • 144.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Adolfsson, Karin H.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    De Lima, Sara
    Karolinska Inst, St Erik Eye Hosp, Div Ophthalmol & Vis, Dept Clin Neurosci, Stockholm, Sweden..
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    In vitro and in vivo effects of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A2018In: Clinical and experimental optometry, ISSN 0816-4622, E-ISSN 1444-0938, Vol. 101, no 3, p. 354-362Article in journal (Refereed)
    Abstract [en]

    Background: Acuvue Oasys silicone hydrogel contact lenses (Senofilcon A) are used as bandage lenses and often combined with ophthalmic solutions in the treatment of ocular diseases. Concerns have been raised regarding the compatibility and effect of eye-drop solutions on the bandage lenses, which have led to frequent replacement of lenses causing clinical problems. Some patients experience pain or discomfort during treatments and the accumulation of drugs and preservatives in lenses has been suggested as a possible reason. The aim with this study was to investigate the effect of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A in vitro and in vivo. Methods: The effect of three common ophthalmic solutions Isopto-Maxidex, Timosan and Oftaquix on Acuvue Oasys (Senofilcon A) bandage lenses was evaluated. An in vitro model method was developed where drug and preservative uptake by Acuvue Oasys was monitored with ultraviolet-visible spectroscopy and laser desorption ionisation mass spectrometry. Surface morphology changes of the lenses were evaluated using scanning electron microscopy. The method was then implemented for the in vivo pilot study evaluating lenses worn by patients. Results: In vitro model study monitoring the drug and preservatives uptake showed that the active ingredients from all the eye drops together with preservatives were taken up by the lenses in significant amounts. For the in vivo study no traces of active ingredients or preservatives could be found on the worn and treated lenses regardless of time being worn or dosage profiles. The surface morphology changes in the in vivo study were also minor in contrast to the changes observed in the in vitro scanning electron microscopy images. Conclusion: The in vivo results demonstrate minor effects of the ophthalmic solutions on the worn lenses. These results do not support the building up of preservatives and drugs on the contact lenses as the cause of pain or discomfort experienced by some patients, which is encouraging for the use of bandage lenses in combination with ophthalmic solutions.

  • 145.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Construction of Bioactive and Reinforced Bioresorbable Nanocomposites by Reduced Nano-Graphene Oxide Carbon Dots2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 1074-1081Article in journal (Refereed)
    Abstract [en]

    Bioactive and reinforced poly(ϵ-caprolactone) (PCL) films were constructed by incorporation of cellulose derived reduced nanographene oxide (r-nGO) carbon nanodots. Two different microwave-assisted reduction routes in superheated water were utilized to obtain r-nGO and r-nGO-CA. For the latter, a green reducing agent caffeic acid (CA), was incorporated in the reduction process. The materials were extruded and compression molded to obtain proper dispersion of the carbon nanodots in the polymer matrix. FTIR results revealed favorable interactions between r-nGO-CA and PCL that improved the dispersion of r-nGO-CA. r-nGO, and r-nGO-CA endorsed PCL with several advantageous functionalities including improved storage modulus and creep resistance. The considerable increase in storage modulus demonstrated that the carbon nanodots had a significant reinforcing effect on PCL. The PCL films with r-nGO-CA were also evaluated for their osteobioactivity and cytocompatibility. Bioactivity was demonstrated by formation of hydroxyapatite (HA) minerals on the surface of r-nGO-CA loaded nanocomposites. At the same time, the good cytocompatibility of PCL was retained as illustrated by the good cell viability to MG63 osteoblast-like cells giving promise for bone tissue engineering applications.

  • 146.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Degradation of Cellulose Derivatives in Laboratory, Man-Made, and Natural Environments2022In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 23, no 7, p. 2713-2729Article in journal (Refereed)
    Abstract [en]

    Biodegradable polymers complement recyclable materials in battling plastic waste because some products are difficult to recycle and some will end up in the environment either because of their application or due to wear of the products. Natural biopolymers, such as cellulose, are inherently biodegradable, but chemical modification typically required for the obtainment of thermoplastic properties, solubility, or other desired material properties can hinder or even prevent the biodegradation process. This Review summarizes current knowledge on the degradation of common cellulose derivatives in different laboratory, natural, and man-made environments. Depending on the environment, the degradation can be solely biodegradation or a combination of several processes, such as chemical and enzymatic hydrolysis, photodegradation, and oxidation. It is clear that the type of modification and especially the degree of substitution are important factors controlling the degradation process of cellulose derivatives in combination with the degradation environment. The big variation of conditions in different environments is also briefly considered as well as the importance of the proper testing environment, characterization of the degradation process, and confirmation of biodegradability. To ensure full sustainability of the new cellulose derivatives under development, the expected end-of-life scenario, whether material recycling or "biological"recycling, should be included as an important design parameter. 

  • 147.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Blomqvist, Anders
    Stockholm Vetenskapens Hus, Stockholm, SE-106 91, Sweden.
    Polymer, giant molecules with properties: An entertaining activity introducing polymers to young students2019In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 96, no 8, p. 1691-1695Article in journal (Refereed)
    Abstract [en]

    In this activity, polymer materials are introduced to 13–16 year old students. The activity is aimed at students with no or little knowledge of polymers. An engaging lecture covering the basics of polymer technology and sustainable development in the plastics field is presented. Important polymers such as polyethylene (PE), cellulose, and polylactide (PLA) are presented, and examples of their everyday use are shown. Quiz questions are employed in the introductory lecture to engage the students, to start discussions, and to evaluate the learning progress. The students are then engaged in two entertaining activities involving a natural polymer alginate and superabsorbent polymers. Alginate spaghetti is produced using different salt solutions enabling the students to create and destroy materials just by playing around with the chemistry, which helps them understand the polymeric material. The second activity has an application-based approach where the ability of superabsorbent polymers in diapers to retain water is investigated. The overall quiz results and discussions after the activities show an improved understanding of polymers and their applications and properties, making this activity useful for teaching polymers to young students.

  • 148.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lando, Gabriela Albara
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Univ Fed Rio Grande Sul UFRGS, Inst Chem, Dept Phys Chem, Av Bento Goncalves 9500, BR-91501970 Porto Alegre, RS, Brazil..
    Yadav, Anilkumar
    Indian Inst Technol Delhi, Dept Text & Fibre Engn, New Delhi 110016, India..
    Srivastava, Rajiv K.
    Indian Inst Technol Delhi, Dept Text & Fibre Engn, New Delhi 110016, India..
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hydrolytic Degradation of Porous Crosslinked Poly(epsilon-Caprolactone) Synthesized by High Internal Phase Emulsion Templating2020In: Polymers, E-ISSN 2073-4360, Vol. 12, no 8, article id 1849Article in journal (Refereed)
    Abstract [en]

    Porous poly(epsilon-caprolactone) (PCL) scaffolds were fabricated using the high internal polymerization emulsion (HIPE) technique. Bis(epsilon-caprolactone-4-yl) (BCY) was utilized as crosslinker. The crosslinking density and the volume fraction of the dispersed phase were varied in order to study the potential effect of these parameters on the hydrolytic degradation at 37 degrees C and 60 degrees C. After different hydrolysis times the remaining solid samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), while the degradation products in the aqueous aging solutions were analyzed by laser desorption ionization-mass spectrometry (LDI-MS). The effect of temperature on the degradation process and release of degradation products was, as expected, significant. The temperature effect was also shown by FTIR analysis that displayed a pronounced increase in the intensity of the hydroxyl-group absorption band after 70 days of hydrolysis at 60 degrees C indicating significant cleavage of the polymer chains. LDI-MS analysis proved the release of oligomers ranging from dimers to hexamers. The product patterns were similar, but the relativem/zsignal intensities increased with increasing time, temperature and crosslinking density, indicating larger amounts of released products. The latter is probably due to the decreasing degree of crystallinity as a function of amount of crosslinker. The porous structure and morphology of the scaffolds were lost during the aging. The higher the crosslinking density, the longer the scaffolds retained their original porous structure and morphology.

  • 149.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Yao, Jenevieve G.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Cellulose-Derived Nanographene Oxide Surface-Functionalized Three-Dimensional Scaffolds with Drug Delivery Capability2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 738-749Article in journal (Refereed)
    Abstract [en]

    Multifunctional three-dimensional (3D) scaffolds were targeted by surface grafting cellulose-derived nanographene oxide (nGO) on the surface of porous poly(epsilon-caprolactone) (PCL) scaffolds. nGO was derived from cellulose by microwave-assisted carbonization process and covalently grafted onto aminolyzed PCL scaffolds through an aqueous solution process. Fourier transform infrared spectroscopy and thermogravimetric analysis both verified the successful attachment of nGO and scanning electron microscopy depicted a homogeneous dispersion of nGO over the scaffold surface. Mechanical tests were performed and demonstrated a significant increase in compressive strength for the nGO grafted scaffolds. Grafting of nGO was also shown to induce mineralization with the formation of calcium phosphate precipitates on the surface of the scaffolds with the size increasing with higher nGO content. The potential of surface-grafted nGO as a nanocarrier of an antibiotic drug was also explored. The secondary interactions between nGO and ciprofloxacin, a broad-spectrum antibiotic used in the treatment of osteomyelitis, were optimized by controlling the solution pH. Ciprofloxacin was found to be adsorbed most strongly in its cationic form at pH 5, in which pi-pi electron donor-acceptor interactions predominate and the adsorbed drug content increased with increasing nGO amount. Further, the release kinetics of the drug were investigated during 8 days. In conclusion, the proposed simple fabrication process led to a scaffold with multifunctionality in the form of improved mechanical strength, ability to induce mineralization, as well as drug loading and delivery capability.

  • 150.
    Bera, Anup Kumar
    et al.
    UGC DAE Consortium Sci Res, Khandwa Rd, Indore 452001, India..
    Dev, Arun Singh
    UGC DAE Consortium Sci Res, Khandwa Rd, Indore 452001, India..
    Kuila, Manik
    UGC DAE Consortium Sci Res, Khandwa Rd, Indore 452001, India..
    Ranjan, Mukesh
    Inst Plasma Res, FCIPT, Bhat 382428, Gandhinagar, India..
    Pandit, Pallavi
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;KTH Royal Inst Technol, S-10044 Stockholm, Sweden..
    Reddy, Varimalla R.
    UGC DAE Consortium Sci Res, Khandwa Rd, Indore 452001, India..
    Kumar, Dileep
    UGC DAE Consortium Sci Res, Khandwa Rd, Indore 452001, India..
    Morphology induced large magnetic anisotropy in obliquely grown nanostructured thin film on nanopatterned substrate2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 581, article id 152377Article in journal (Refereed)
    Abstract [en]

    The artificial tailoring of magnetic anisotropy by manipulating surface and interface morphology is attracting widespread interest for its application in spintronic and magnetic memory devices. Here oblique angle deposition on a nanopatterned rippled substrate is presented as a novel route of inducing large in-plane uniaxial magnetic anisotropy (UMA) in magnetic thin films. For this purpose, Cobalt films and rippled SiO2 substrates have been taken as a model system for the present study. Here, nanopatterned substrates are prepared by low energy ion beam erosion (IBE), above which films are deposited obliquely along and normal to the ripple directions. A clear anisotropy in the growth behavior has been observed due to the inhomogeneous in-plane organization of adatoms in the form of columns. The increased shadowing effect in the films deposited obliquely normal to the direction of the ripple patterns causes preferential coalescence of the columns along the substrate ripples, resulting in stronger in-plane UMA in the film. This peculiarity in magnetic behavior is addressed by considering the morphological anisotropy governed by enhanced shadowing effect, the shape anisotropy and the dipolar interactions among the magnetostatically coupled ripple structure.

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