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  • 151.
    Erlandsson, Johan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    López Durán, Veronica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Granberg, Hjalmar
    Innventia AB.
    Sandberg, Mats
    Acreo Swedish ICT AB.
    Larsson, Per A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Macro- and mesoporous nanocellulose beads for use in energy storage devices2016Ingår i: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 5, s. 246-254Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chemically cross-linked, wet-stable cellulose nanofibril (CNF) aerogel beads were fabricated using a novel procedure. The procedure facilitated controlled production of millimetre-sized CNF aerogel beads without freeze-drying or critical point drying, while still retaining a highly porous structure with low density. The aerogel beads were mechanically robust in the dry state, supporting loads of 1.3 N at 70% compression, even after being soaked in water and re-dried. Furthermore, they displayed both a good stability in water and a remarkably good shape recovery after wet compression. Owing to the stability in water, the entire surface of the highly porous aerogel beads could be successfully functionalized with polyelectrolytes and carboxyl-functionalized single-wall carbon nanotubes (CF-SWCNTs) using the Layer-by-Layer technique, introducing a significant electrical conductivity (1.6 mS/cm) to the aerogel beads. The functionalized, electrically conducting aerogel beads could carry as much as 2 kA/cm(2) and act as electrodes in a supercapacitor displaying a stabilized charge storage capacity of 9.8 F/g after 50 charging-discharging cycles.

  • 152.
    Erlandsson, Johan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ingverud, Tobias
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Granberg, H.
    Larsson, Per A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    On the mechanism behind freezing-induced chemical crosslinking in ice-templated cellulose nanofibril aerogels2018Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 40, s. 19371-19380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The underlying mechanism related to freezing-induced crosslinking of aldehyde-containing cellulose nanofibrils (CNFs) has been investigated, and the critical parameters behind this process have been identified. The aldehydes introduced by periodate oxidation allows for formation of hemiacetal bonds between the CNFs provided the fibrils are in sufficiently close contact before the water is removed. This is achieved during the freezing process where the cellulose components are initially separated, and the growth of ice crystals forces the CNFs to come into contact in the thin lamellae between the ice crystals. The crosslinked 3-D structure of the CNFs can subsequently be dried under ambient conditions after solvent exchange and still maintain a remarkably low density of 35 kg m-3, i.e. a porosity greater than 98%. A lower critical amount of aldehydes, 0.6 mmol g-1, was found necessary in order to generate a crosslinked 3-D CNF structure of sufficient strength not to collapse during the ambient drying. The chemical stability of the 3-D structure can be further enhanced by converting the hemiacetals to acetals by treatment with an alcohol under acidic conditions.

  • 153.
    Farahani, Saina Kishani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Escalante, Alfredo
    Toriz, Guillermo
    Vilaplana, Francisco
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Gatenholm, Paul
    Hansson, Per
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Experimental and Theoretical Evaluation of the Solubility/Insolubility Spruce Xylan (Arabino Glucuronoxylan)2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 3, s. 1263-1270Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The molecular solubility of softwood arabinoglucuronoxylan (AGX) has been thoroughly investigated, and it has been shown that the chemical and physical structures of the extracted hemicellulose are not significantly influenced by different purification steps, but a transient molecular solubility of AGX was observed in aqueous media at low concentrations (1 g/L) when the dissolved macromolecules had a hydrodynamic diameter of up to 10 nm. A phase separation was detected when the concentration was increased to 15 g/L leading to an association of the smaller molecules into fractal structures with a considerably larger diameter, even though the dispersions were still transparent to ocular inspection. Dynamic Light Scattering and Cryo-Transmission Electron Microscopy showed dimensions in the range of 1000 nm. The phase separation of the sample was further characterized by estimating the χ-interaction parameter of AGX in water using the Flory-Huggins theory, and the results supported that water is a poor solvent for AGX. This behavior is crucial when films and hydrogels based on these biopolymers are made, since the association will dramatically affect barrier and mechanical properties of films made from these materials.

  • 154.
    Farahani, Saina Kishani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Vilaplana, Francisco
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hansson, Per
    Uppsala Univ, Uppsala, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Influence of solubility on the adsorption of different Xyloglucan fractions to cellulose model surfaces2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 155.
    Farahani, Saina Kishani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Vilaplana, Francisco
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Ruda, Marcus
    Ren Com AB, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Hansson, Per
    Uppsala Univ, Dept Pharm, Box 580, S-75123 Uppsala, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Influence of Solubility on the Adsorption of Different Xyloglucan Fractions at Cellulose-Water Interfaces2020Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 21, nr 2, s. 772-782Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Xylogucan (XG) fractions with different molar masses were prepared while preserving the natural structure of the XG. The solubility of the fractions was investigated using light scattering, chromatography, and microscopy techniques. The conformational changes of the XG molecules and their association and phase separation were investigated together with concentration and molar mass changes. The knowledge gained was then applied to investigate the interaction of different XG fractions at cellulose model surfaces using a quartz crystal microbalance with dissipation. The results indicate that there is a cluster formation and phase separation of the XG molecules at the cellulose/water interface induced by the increase in XG concentration close to the surface. Concomitantly, the adsorption regimes are altered for the XG fractions depending on the solubility properties, indicating that the insolubility, association, and phase separation of XGs in aqueous media affect their interaction with cellulose. The study is of vital importance for improving the functionality of sustainable materials made from xyloglucan/cellulose natural composites.

  • 156.
    Farahani, Saina Kishani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Vilaplana, Francisco
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    Ruda, Marcus
    Hansson, Per
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    The influence of solubility on the adsorption of different Xyloglucan fractions at Cellulose Water InterfacesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Xylogucan (XG) fractions with different molar masses were prepared while preserving the natural structure of the XG. The solubility of the fractions was investigated using light- scattering, chromatography and microscopy techniques. The conformational changes of the XG molecules and their association and phase separation were investigated together with concentration and molar mass changes. The knowledge gained was then applied to investigate the interaction of different XG fractions at cellulose model surfaces using a quartz crystal microbalance with dissipation. The results indicate that there is a cluster formation and phase separation of the XG molecules at the cellulose/water interface induced by the increase in XG concentration close to the surface. Concomitantly, the adsorption regimes are altered for the XG fractions depending on the solubility properties, indicating that the insolubility, association and phase separation of XGs in aqueous media affect their interaction with cellulose. The study is of vital importance for improving the functionality of sustainable materials made from xyloglucan/cellulose natural composites.

  • 157.
    Farhat, Wissam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Biundo, Antonino
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Stamm, Arne
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Malmström, Eva
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Syrén, Per-Olof
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Lactone monomers obtained by enzyme catalysis and their use in reversible thermoresponsive networks2020Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 137, nr 18, artikel-id 48949Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enzyme-catalyzed transformations have a great potential in both the pharmaceutical and chemical industry to achieve complex and (stereo)selective synthesis under mild reaction conditions. Still, the implementation of biocatalysis in the prerequisite upgrading of inert synthons into activated monomers for polymer applications has not yet been fully realized. In this contribution, we show that scaled-up synthesis of bicyclic norcamphor lactone using an engineered Baeyer–Villiger monooxygenase (BVMO) is feasible to reach complete conversion of the corresponding ketone in 24 h in shake-flask. The lactone monomer obtained by enzyme catalysis was copolymerized with ε-caprolactone via ring-opening polymerization to study the impact of the additional ring on material properties. Moreover, four-arm star-like, homo and block copolymers were designed from ε-caprolactone, ε-decalactone, and norcamphor lactone and characterized for their structural and thermal properties. These newly explored macromolecules were functionalized with furan rings using the enzyme Candida antarctica lipase B which allowed the formation of thermolabile networks via the pericyclic reaction with bismaleimide by means of Diels–Alder chemistry. The bonding/debonding state of these star-like based materials can be tuned by a suitable selection of thermal treatment. The temperature-dependent reversibility was assessed by thermal analysis and solubility test. Our results presented here shed light on the high potential of the use of chemoenzymatic approaches in the synthesis of new functional materials with tuned physiochemical properties.

  • 158.
    Farhat, Wissam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Stamm, Arne
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Robert-Monpate, Maxime
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Centra, Science for Life Laboratory, SciLifeLab. Ecole Super Chim Organ & Minerale, 1 Allee Reseau Jean Marie Buckmaster, F-60200 Compiegne, France.
    Biundo, Antonino
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Syrén, Per-Olof
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Biocatalysis for terpene-based polymers2019Ingår i: Zeitschrift für Naturforschung C - A Journal of Biosciences, ISSN 0939-5075, E-ISSN 1865-7125, Vol. 74, nr 3-4, s. 90-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accelerated generation of bio-based materials is vital to replace current synthetic polymers obtained from petroleum with more sustainable options. However, many building blocks available from renewable resources mainly contain unreactive carbon-carbon bonds, which obstructs their efficient polymerization. Herein, we highlight the potential of applying biocatalysis to afford tailored functionalization of the inert carbocyclic core of multicyclic terpenes toward advanced materials. As a showcase, we unlock the inherent monomer reactivity of norcamphor, a bicyclic ketone used as a monoterpene model system in this study, to afford polyesters with unprecedented backbones. The efficiencies of the chemical and enzymatic Baeyer-Villiger transformation in generating key lactone intermediates are compared. The concepts discussed herein are widely applicable for the valorization of terpenes and other cyclic building blocks using chemoenzymatic strategies.

  • 159. Fei, Ye
    et al.
    Barrefelt, Åsa
    Asem, Heba
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Abedi-Valugerdi, Manuchehr
    El-Serafi, Ibrahim
    Saghafian, Maryam
    Abu-Salah, Khalid
    Alrokayan, Salman
    Muhammed, Mamoun
    Hassan, Moustapha
    Biodegradable polymeric vesicles containing magnetic nanoparticles,quantum dots and anticancer drugs for drug delivery and imaging2014Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 35, s. 3885-3894Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have developed biodegradable polymeric vesicles as a nanocarrier system for multimodal bio-imaging and anticancer drug delivery. The poly(lactic-co-glycolic acid) (PLGA) vesicles were fabricated by encapsulating inorganic imaging agents of superparamagnetic iron oxide nanoparticles (SPION), manganese-doped zinc sulfide (Mn:ZnS) quantum dots (QDs) and the anticancer drug busulfan into PLGA nanoparticles via an emulsion-evaporation method. T2∗-weighted magnetic resonance imaging (MRI) of PLGA-SPION-Mn:ZnS phantoms exhibited enhanced negative contrast with r2∗ relaxivity of approximately 523 s(-1) mM(-1) Fe. Murine macrophage (J774A) cellular uptake of PLGA vesicles started fluorescence imaging at 2 h and reached maximum intensity at 24 h incubation. The drug delivery ability of PLGA vesicles was demonstrated in vitro by release of busulfan. PLGA vesicle degradation was studied in vitro, showing that approximately 32% was degraded into lactic and glycolic acid over a period of 5 weeks. The biodistribution of PLGA vesicles was investigated in vivo by MRI in a rat model. Change of contrast in the liver could be visualized by MRI after 7 min and maximal signal loss detected after 4 h post-injection of PLGA vesicles. Histological studies showed that the presence of PLGA vesicles in organs was shifted from the lungs to the liver and spleen over time.

  • 160.
    Feng, Nianjie
    et al.
    Hubei Univ Technol, Wuhan 430068, Hubei, Peoples R China.;Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Guo, Lifang
    Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Ren, Hao
    Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Xie, Yimin
    Hubei Univ Technol, Wuhan 430068, Hubei, Peoples R China..
    Jiang, Zhihua
    Auburn Univ, Alabama Ctr Paper & Bioresource Engn, Auburn, AL 36849 USA..
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Zhai, Huamin
    Nanjing Forestry Univ, Nanjing 210037, Jiangsu, Peoples R China..
    Changes in chemical structures of wheat straw auto-hydrolysis lignin by 3-hydroxyanthranilic acid as a laccase mediator2019Ingår i: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 122, s. 210-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    3-Hydroxyanthranilic acid (3-HAA), as a potential natural laccase mediator, was shown to mediate the oxidation of non-phenolic lignin subunits. The problem of cost and toxicity of artificial mediators could be solved to some extent by a further study about the detailed changes of lignin chemistry structures in laccase 3-HAA system (LHS). In this work, wheat straw auto-hydrolysis lignin (AL) was prepared. Oxidations of AL by LHS and laccase 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) system were then investigated, respectively. Various structural changes of AL during the oxidation were characterized by different methods including phenolic hydroxyl group determination, nitrobenzene oxidation, ozonation, gel permeation chromatography, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy. The changes in AL chemical structures were found in LHS, including unit removal, bond cleavage and biopolymerization. Compared to laccase ABTS system, a selective removal of guaiacyl-type lignin in LHS was observed, based on the results of nitrobenzene oxidation and 2D NMR analysis. The selective removal of guaiacyl-type lignin was due to improved aromatic ring cleavage and weaken lignin biopolymerization. The selectivity of guaiacyl-type lignin removal in LHS plays an important role, especially for improving bioconversion efficiency of laccase for guaiacyl-rich lignocellulosic biomass.

  • 161.
    Feng, Zhaoxuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    From Polysaccharides to Functional Materials for Trace Pharmaceutical Adsorption2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The transition to bioeconomy will reduce our dependency on fossil fuels as well as contribute to a more sustainable society. Within this framework, exploitation and development of renewable substitutes to petroleum-based products provides feasible roadmap for the material design. Here a perspective is provided to how the natural polysaccharides chitosan (CS) and/or cellulose (CL) could be elaborated and transformed to high-performance materials with the explicit aim of removing trace pharmaceutical contaminants from the wastewater, thus facilitating the sustainable development. In the first part of the thesis, chitosan and cellulose were converted to the carbon spheres (C-sphere) through a microwave-assisted hydrothermal carbonization process, and C-sphere was further broken down to the nanographene oxide (nGO) via a simple oxidation route. On this foundation, a green pathway was developed for fabrication of biobased materials for wastewater purification. First, macroporous chitosan-based composite hydrogels with controllable properties were developed, where chitosan-derived nGO worked as a functional property enhancer. Second, a further development changing from the bulky hydrogels to microgels consisting of CS composite particles in the microscopic size was achieved by a fast one-pot spraying-drying process. The crosslinking reaction occurred in situ during the spray-drying. Last, the C-sphere by-itself was also believed to be a potential adsorbent for wastewater contaminants. In the next step the prepared systems were evaluated for their capacity to adsorb pharmaceutical contaminants. Diclofenac sodium (DCF) was utilized as the model drug, and the three fabricated bio-adsorbents all demonstrated effective DCF adsorption performance, with the adsorption efficiency varying from 65.6 to 100%. Moreover, the DCF adsorption kinetics, isotherms and thermodynamic study were also investigated to reveal the nature of the adsorption process with the different materials. Finally, chitosan-based microspheres were selected for the reusability study, with the adsorption efficiency above 70% retained after six adsorption-desorption cycles, thus further endowing the promising potential of the fabricated bio-adsorbents for commercial applications.

    Ladda ner fulltext (pdf)
    thesis
  • 162.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Gruetzmacher, Hansjoerg
    Chiappone, Annalisa
    Sangermano, Marco
    Photocrosslinked Chitosan Hydrogels Reinforced with Chitosan-Derived no-Graphene Oxide2019Ingår i: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 220, nr 13, artikel-id 1900174Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chitosan and chitosan-derived nano-graphene oxide carbon dots are successfully methacrylated and utilized for the fabrication of photocurable hydrogels. The addition of the nano-graphene oxide (nGO) does not significantly delay the polymer network build-up, but significantly reduces the storage modulus of the crosslinked network, with important detrimental effects on the mechanical performance. By replacing nGO with methacrylated M-nGO, the mechanical performance of the crosslinked polymer network is improved with an increase of the storage modulus as a function of increasing the M-nGO content in the photocurable formulation.

  • 163.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Tunable chitosan hydrogels for adsorption: Property control by biobased modifiers2018Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 196, s. 135-145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A sustainable strategy to fabricate chitosan-based composite hydrogels with tunable properties and controllable adsorption capacity of trace pharmaceuticals was demonstrated. Two biobased modifiers were utilized to tune the properties, nano-graphene oxide (nGO) derived from chitosan via microwave-assisted carbonization and oxidation, and genipin as the crosslinking agent. An increase in genipin content facilitated an increase in the degree of crosslinking as shown by improved storage modulus and decreased swelling ratio. Increasing nGO content changed the surface microtopography of the hydrogel which correlated with the surface wettability. nGO also catalyzed the genipin-crosslinking reaction. The hydrogel was further shown to be an effective adsorbent for a common anti-inflammatory drug, diclofenac sodium (DCF), with the removal efficiency ranging from 91 to 100% after 48 h. DCF adsorption efficiency could be tuned through simple alteration of nGO and genipin concentration, which provides promising potential for this environmental-friendly adsorbent in removal of DCF from pharmaceutical waste water.

  • 164.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Rajarao, Gunaratna Kuttuva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Microwave carbonized cellulose for trace pharmaceutical adsorption2018Ingår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 346, s. 557-566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A promising sustainable strategy to valorize cellulose to high-value adsorbents for trace pharmaceuticals, like diclofenac sodium (DCF), in the water is demonstrated. Carbon nanospheres (CN) as the DCF adsorbent were derived from cellulose through a one-pot microwave-assisted hydrothermal carbonization method. CN exhibited efficient DCF removal (100% removal of 0.001 mg/mL DCF in 30 s and 59% removal of 0.01 mg/mL DCF in 1 h). The adsorption kinetics and isotherm data were well-fitted with the pseudo-second-order kinetic model and Langmuir model, respectively. The adsorption process was endothermic and spontaneous as confirmed by the thermodynamic parameters. Multiple characterization techniques including SEM/EDS, FTIR, FTIR-imaging and zeta potential were applied to qualitatively investigate the adsorption process. π-π stacking and hydrogen bonding were proposed as the dominant adsorption interactions. CN also demonstrated effective adsorption capacity towards three other commonly-detected contaminants in the wastewater including ketoprofen (KP), benzophenone (BZP), and diphenylamine (DPA), each bearing partial structural similarity with DCF. The affinity of the contaminants towards CN followed the order DPA > BZP > DCF > KP, which could be explained by the different configurations and chemical units. It was speculated that for DCF and KP, the steric hindrance and electrostatic repulsion produced by dissociated carboxyl groups can impede the adsorption process as compared to DPA and BZP. This methodology could offer further insights into the drug adsorption on the cellulose-derived carbon adsorbents and the use of bioderived carbons for treatment of wastewaters contaminated with pharmaceuticals.

  • 165.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Takahiro, Danjo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Tadahisa, Iwata
    Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo.
    Albertsson, Ann-Christine
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Recyclable fully biobased chitosan adsorbents spray-dried in one-pot to microscopic size and enhanced adsorption capacity2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 5, s. 1956-1964Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A facile one-pot spray-drying process was developed for fabrication and in-situ crosslinking of chitosan microspheres to improve the adsorption capacity by microscopic design. A fully biobased nature was achieved by utilizing genipin (GP) as a crosslinking agent and chitosan derived nano-graphene oxide (nGO) as a property tuner. The produced chitosan microspheres were further proven as powerful adsorbents for common wastewater contaminants such as anionic dyes and pharmaceutical contaminants, here modelled by methyl orange (MO) and diclofenac sodium (DCF). By regulating the amount of GP and nGO, as well as by controlling the process parameters including the spraydrying inlet temperature and post-heat treatment, the surface morphology, size, zeta potential and adsorption efficiency of the microspheres could be tuned accordingly. The adsorption efficiency for MO and DCF reached 98.9 and 100 %, respectively. The microspheres retained high DCF adsorption efficiency after six adsorption and desorption cycles and the recyclability was improved by incorporated nGO. The fabricated microspheres, thus, have great potential as reusable and eco-friendly adsorbents.

  • 166.
    Finnveden, Maja
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Brännström, Sara
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Johansson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Martinelle, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Novel sustainable synthesis of vinyl ether ester building blocks, directly from carboxylic acids and the corresponding hydroxyl vinyl ether, and their photopolymerization2018Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, nr 44, s. 24716-24723Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increased environmental awareness has led to a demand for sustainable, bio-based materials. Consequently, the development of new benign synthesis pathways utilizing a minimum of reaction steps and available bio-based building blocks is needed. In the present study, vinyl ether alcohols and functional carboxylic acids were used to synthesize bifunctional vinyl ether esters using the immobilized enzyme Candida antarctica lipase B as a catalyst. Vinyl ethers are attractive alternatives to (meth)acrylates due to low allergenic hazards, low toxicity, and fast polymerization; however, difficult synthesis limits the monomer availability. The synthesis was performed in one-pot and the described method was successful within a broad temperature range (22-90 degrees C) and in various organic solvents as well as in the bulk. The synthesis of different vinyl ether esters reached high conversions (above 90%) after less than 1 h and products were purified by removing the enzyme by filtration using only small amounts of acetone. This approach is a straightforward route to reach monomers with multiple types of functionalities that can be used as different photo-curable thermoset resins. In this work, this was demonstrated by polymerizing the monomers with cationic and radical UV-polymerization. By changing the functional carboxylic acids, the architecture of the final polymer can be tailored, herein demonstrated by two examples. In the developed versatile method, carboxylic acids can be used directly as acyl donors, constituting a more sustainable alternative to the carboxylic acid derivatives used today.

  • 167.
    Finnveden, Maja
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Hendil-Forssell, Peter
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Claudino, Mauro
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Johansson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Martinelle, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Lipase-Catalyzed Synthesis of Renewable Plant Oil-Based Polyamides.2019Ingår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 11, nr 11, artikel-id 1730Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enzyme catalyzed synthesis of renewable polyamides was investigated using Candida antarctica lipase B. A fatty acid-derived AB-type functional monomer, having one amine and one methyl ester functionality, was homopolymerized at 80 and 140 °C. Additionally, the organobase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was used as a catalyst. The results from the two catalysts were comparable. However, the amount of lipase added was 1.2 × 103 times lower, showing that the lipase was a more efficient catalyst for this system as compared to TBD. Moreover, the AB-type monomer was copolymerized with 1,12-diaminododecane to synthesize oligoamides of two different lengths.

  • 168.
    Fogelström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Norström, Emelie
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Khabbaz, Farideh
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Brucher, Jorg
    Holmen, Holmen Dev, Örnskoldsvik, Sweden..
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH Royal Inst Technol, Wallenberg Wood Sci Ctr, Stockholm, Sweden.;KTH Royal Inst Technol, Dept Fibre & Polymer Technol, Stockholm, Sweden..
    A fully green wood adhesive based on hemicelluloses derived from pulp processes2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 169.
    Fogelström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Stamm, Arne
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Tengdelius, Mattias
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Syrén, Per-Olof
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Malmström, Eva
    KTH Royal Inst Technol, Dept Fibre & Polymer Technol, Stockholm, Sweden..
    New chemo-enzymatic pathways for sustainable terpene-based polymeric materials2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 170.
    Forsberg, Viviane
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. Mid Sweden Univ, FSCN, Surface & Colloid Engn, Holmgatan 10, SE-85170 Sundsvall, Sweden..
    Maslik, Jan
    Tomas Bata Univ Zlin, Ctr Polymer Syst, Trida Tomase Bati 5678, CZ-76001 Zlin, Czech Republic..
    Norgren, Magnus
    Mid Sweden Univ, FSCN, Surface & Colloid Engn, Holmgatan 10, SE-85170 Sundsvall, Sweden..
    Electronic performance of printed PEDOT:PSS lines correlated to the physical and chemical properties of coated inkjet papers2019Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 41, s. 23925-23938Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PEDOT:PSS organic printed electronics chemical interactions with the ink-receiving layer (IRL) of monopolar inkjet paper substrates and coating color composition were evaluated through Raman spectroscopy mapping in Z (depth) and (XY) direction, Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Other evaluated properties of the IRLs were pore size distribution (PSD), surface roughness, ink de-wetting, surface energy and the impact of such characteristics on the electronics performance of the printed layers. Resin-coated inkjet papers were compared to a multilayer coated paper substrate that also contained an IRL but did not contain the plastic polyethylene (PE) resin layer. This substrate showed better electronic performance (i.e., lower sheet resistance), which we attributed to the inert coating composition, higher surface roughness and higher polarity of the surface which influenced the de-wetting of the ink. The novelty is that this substrate was rougher and with somewhat lower printing quality but with better electronic performance and the advantage of not having PE in their composite structure, which favors recycling.

  • 171.
    Francon, Hugo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Benselfelt, Tobias
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Granberg, Hjalmar
    RISE Bioecon, Stockholm, Sweden..
    Larsson, Per A.
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    3D printable nanocellulose aerogels via a green crosslinking approach and a facile evaporation procedure2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 172.
    Francon, Hugo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lopez Duran, Veronica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Granberg, Hjalmar
    RISE Bioecon, Stockholm, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Novel method for producing formable low-density materials from self-assembled cellulose nanofibrils2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 173.
    Frodeson, Stefan
    et al.
    Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Lindén, Pär
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    Karlstad Univ, Dept Engn & Chem Sci, Chem Engn, SE-65188 Karlstad, Sweden..
    Berghel, Jonas
    Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Compression of Biomass Substances-A Study on Springback Effects and Color Formation in Pellet Manufacture2019Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 9, nr 20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to increase the use of a variated raw material base for pellet production with a maintained density level, knowledge of the biomaterials' ability to counteract any springback effects is essential. In this study, the springback effects were investigated for single press produced pellets from cellulose, hemicelluloses, pectin, and two woods at different moisture contents. The change in pellet coloring was also tested through a spectrophotometer for both xylan and carboxymethyl cellulose (CMC) pellets. The results show that the density of xylan pellets is much higher than glucomannan, for both green and cured pellets, and that the length of the pellets, as well as springback contribution, differ between the hemicelluloses. The study also presents results showing that both xylan and CMC pellets have a mutually identical spectrum and that the changes in the structure of xylan are not only related to moisture content, but are also pressure-related. The study also postulates that the color difference of the xylan pellets is a result of physical changes in the structure, as opposed to being of a chemical nature.

  • 174.
    Fu, Qiliang
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hierarchically structured nanoporous template based on balsa wood2016Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Artikel i tidskrift (Övrigt vetenskapligt)
  • 175.
    Fu, Qiliang
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Honeycomb like templates prepared from balsa wood2015Ingår i: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the current study, we have used sodium chlorite and sodium hydroxide as extraction solutions, to remove lignin and hemicelluloses from the Balsa (Ochroma Lagopus) wood tissues, without damaging the wood honeycomb architecture. Surface morphologies are studied using scanning electron microscopy (SEM). In addition, sugars analysis of the chemically extracted wood is reported. 

  • 176.
    Fu, Qiliang
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Yan, Min
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Jungstedt, Erik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Yang, Xuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Transparent plywood as a load-bearing and luminescent biocomposite2018Ingår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 164, s. 296-303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood (TW) structures in research studies were either thin and highly anisotropic or thick and isotropic but weak. Here, transparent plywood (TPW) laminates are investigated as load-bearing biocomposites with tunable mechanical and optical performances. Structure-property relationships are analyzed. The plies of TPW were laminated with controlled fiber directions and predetermined stacking sequence in order to control the directional dependence of modulus and strength, which would give improved properties in the weakest direction. Also, the angular dependent light scattering intensities were investigated and showed more uniform distribution. Luminescent TPW was prepared by incorporation of quantum dots (QDs) for potential lighting applications. TPW can be designed for large-scale use where multiaxial load-bearing performance is combined with new optical functionalities.

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  • 177.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ahlinder, Astrid
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Jain, Shubham
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mustafa, Kamal
    Univ Bergen, Fac Med, Dept Clin Dent, N-5020 Bergen, Norway..
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Poly(epsilon-caprolactone-co-p-dioxanone): a Degradable and Printable Copolymer for Pliable 3D Scaffolds Fabrication toward Adipose Tissue Regeneration2020Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 21, nr 1, s. 188-198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The advancement of 3D printing technologies in the fabrication of degradable scaffolds for tissue engineering includes, from the standpoint of the polymer chemists, an urgent need to develop new materials that can be used as ink and are suitable for medical applications. Here, we demonstrate that a copolymer of epsilon-caprolactone (CL) with low amounts of p-dioxanone (DX) (15 mol %) is a degradable and printable material that suits the requirements of melt extrusion 3D printing technologies, including negligible degradation during thermal processing. It is therefore a potential candidate for soft tissue regeneration. The semicrystalline CL/DX copolymer is processed at a lower temperature than a commercial polycaprolactone (PCL), shaped as a filament for melt extrusion 3D printing and as porous and pliable scaffolds with a gradient design. Scaffolds have Young's modulus in the range of 60-80 MPa, values suitable for provision of structural support for damaged soft tissue such as breast tissue. SEM and confocal microscope indicate that the CL/DX copolymer scaffolds support adipose stem cell attachment, spreading, and proliferation.

  • 178.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ahlinder, Astrid
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Jain, Shubham
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mustafa, Kamal
    Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, 5020 Bergen, Norway.
    Finne Wistrand, Anna
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    Poly(ϵ-caprolactone-co-p-dioxanone): A Degradable and Printable Copolymer for Pliable 3D Scaffolds Fabrication toward Adipose Tissue Regeneration2020Ingår i: Biomacromolecules, Vol. 21, nr 1, s. 188-198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The advancement of 3D printing technologies in the fabrication of degradable scaffolds for tissue engineering includes, from the standpoint of the polymer chemists, an urgent need to develop new materials that can be used as ink and are suitable for medical applications. Here, we demonstrate that a copolymer of ε-caprolactone (CL) with low amounts of p-dioxanone (DX) (15 mol %) is a degradable and printable material that suits the requirements of melt extrusion 3D printing technologies, including negligible degradation during thermal processing. It is therefore a potential candidate for soft tissue regeneration. The semicrystalline CL/DX copolymer is processed at a lower temperature than a commercial polycaprolactone (PCL), shaped as a filament for melt extrusion 3D printing and as porous and pliable scaffolds with a gradient design. Scaffolds have Young’s modulus in the range of 60–80 MPa, values suitable for provision of structural support for damaged soft tissue such as breast tissue. SEM and confocal microscope indicate that the CL/DX copolymer scaffolds support adipose stem cell attachment, spreading, and proliferation.

  • 179.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Enhancing the Properties of Poly(epsilon-caprolactone) by Simple and Effective Random Copolymerization of epsilon-Caprolactone with p-Dioxanone2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 8, s. 3171-3180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have developed a straightforward strategy to obtain semicrystalline and random copolymers of epsilon-caprolactone (CL) and p-dioxanone (DX) with thermal stabilities similar to poly(epsilon-caprolactone), PCL, but with a faster- hydrolytic degradation rate-CL/DX-copolymers-are promising inks when printing scaffolds aimed for tissue engineering. Such copolymers behave similar to PCL and resorb faster. The copolymers were synthesized by bulk ring-opening copolymerization, achieving a high yield; a molecular weight, M-n, of 57-176 kg mol(-1); and an inherent viscosity of 1.7-1.9 dL g(-1). The copolymer microstructure consisted of long CL blocks that are separated by isolated DX units. The block length and the melting point were a linear function of the DX content. The copolymers crystallize as an orthorhombic lattice that is typical for PCL, and they formed more elastic, softer, and less hydrophobic films with faster degradation rates than PCL. Relatively high thermal degradation temperatures (above 250 C), similar to PCL, were estimated by thermogravimetric analysis, and copolymer filaments for three-dimensional printing and scaffolds were produced without thermal degradation.

  • 180.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Synthetic Approaches to Combine the Versatility of the Thiol Chemistry with the Degradability of Aliphatic Polyesters2020Ingår i: POLYMER REVIEWS, ISSN 1558-3724, Vol. 60, nr 1, s. 86-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider optimal sensor scheduling with unknown communication channel statistics. We formulate two types of scheduling problems with the communication rate being a soft or hard constraint, respectively. We first present some structural results on the optimal scheduling policy using dynamic programming and assuming that the channel statistics is known. We prove that the Q-factor is monotonic and submodular, which leads to threshold-like structures in both problems. Then we develop a stochastic approximation and parameter learning frameworks to deal with the two scheduling problems with unknown channel statistics. We utilize their structures to design specialized learning algorithms. We prove the convergence of these algorithms. Performance improvement compared with the standard Q-learning algorithm is shown through numerical examples, which also discuss an alternative method based on recursive estimation of the channel quality.

  • 181.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mathisen, T.
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Minimizing the time gap between service lifetime and complete resorption of degradable melt-spun multifilament fibers2019Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 163, s. 43-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have succeeded to modulated the degradation rate of poly(L-lactide) (PLLA) melt-spun multifilament fibers to extend the service lifetime and increase the resorption rate by using random copolymers of L-lactide and trimethylene carbonate (TMC). The presence of TMC units enabled an overall longer service lifetime but faster degradation kinetics than PLLA. By increasing the amount of TMC up to 18 mol%, multifilament fibers characterized by a homogenous degradation profile could be achieved. Such composition allowed, once the mechanical integrity was lost, a much longer retention of mechanical integrity and a faster rate of mass loss than samples containing less TMC. The degradation profile of multifilament fibers consisting of (co)polymers containing 0, 5, 10 and 18 mol% of TMC has been identified during 45 weeks in vitro hydrolysis following the molecular weight decrease, mass loss and changes in microstructure, crystallinity and mechanical properties. The fibers degraded by a two-step, autocatalyzed bulk hydrolysis mechanism. A high rate of molecular weight decrease and negligible mass loss, with a consequent drop of the mechanical properties, was observed in the early stage of degradation for fibers having TMC content up to 10 mol%. The later stage of degradation was, for these samples, characterized by a slight increase in the mass loss and a negligible molecular weight decrease. Fibers prepared with the 18 mol% TMC copolymer showed instead a more homogenous molecular weight decrease ensuring mechanical integrity for longer time and faster mass loss during the later stage of degradation.

  • 182.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mathisen, Torbjorn
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Poly(L-lactide) and Poly(L-lactide-co-trimethylene carbonate) Melt-Spun Fibers: Structure-Processing-Properties Relationship2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 3, s. 1346-1361Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    l-Lactide/trimethylene carbonate copolymers have been produced as multifilament fibers by high-speed melt-spinning. The relationship existing between the composition, processing parameters and physical properties of the fibers has been disclosed by analyzing how the industrial process induced changes at the macromolecular level, i.e., the chain microstructure and crystallinity development. A poly(l-lactide) and three copolymers having trimethylene carbonate contents of 5, 10 and 18 mol % were synthesized with high molecular weight (M n ) up to 377 kDa and narrow dispersity. Their microstructure, crystallinity and thermal properties were dictated by the composition. The spinnability was then assessed for all the as-polymerized materials: four melt-spun multifilament fibers with increasing linear density were collected for each (co)polymer at a fixed take-up speed of 1800 m min -1 varying the mass throughput during the extrusion. A linear correlation resulted between the as-spun fiber properties and the linear density. The as-spun fibers could be further oriented, developing more crystallinity and improving their tensile properties by a second stage of hot-drawing. This ability was dependent on the composition and crystallinity achieved during the melt-spinning and the parameters selected for the hot-drawing, such as temperature, draw ratio and input speed. The crystalline structure evolved to a more stable form, and the degree of crystallinity increased from 0-52% to 25-66%. Values of tensile strength and Young's modulus up to 0.32-0.61 GPa and 4.9-8.4 GPa were respectively achieved.

  • 183.
    Garcia Gallego, Sandra
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Andrén, Oliver C. J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Accelerated Chemoselective Reactions to Sequence-Controlled Heterolayered Dendrimers2020Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chemoselective reactions are a highly desirable approach to generate well-defined functional macromolecules. Their extraordinary efficiency and selectivity enable the development of flawless structures, such as dendrimers, with unprecedented structure-to-property capacity but with typically tedious synthetic protocols. Here we demonstrate the potency of chemoselective reactions to accomplish sequence-controlled heterolayered dendrimers. An accurate accelerated design of bis-MPA monomers with orthogonally complementary moieties and a wisely selected chemical toolbox generated highly complex monodisperse dendrimers through simplified protocols. The versatility of the strategy was proved by obtaining different dendritic families with different properties after altering the order of addition of the monomers. Moreover, we evaluated the feasibility of the one-pot approach toward these heterolayered dendrimers as proof-of-concept.

  • 184. Garcia-Garcia, D.
    et al.
    Lopez-Martinez, J.
    Balart, R.
    Strömberg, Emma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Moriana, Rosana
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. HIS-University of Skövde, Skövde.
    Reinforcing capability of cellulose nanocrystals obtained from pine cones in a biodegradable poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) thermoplastic blend2018Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 104, s. 10-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, different loads (3, 5 and 7 wt%) of pine cone cellulose nanocrystals (CNCs) were added to films of poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) blends with a composition of 75 wt% PHB and 25 wt% PCL (PHB75/PCL25). The films were obtained after solvent casting followed by melt compounding in an extruder and finally subjected to a thermocompression process. The influence of different CNCs loadings on the mechanical, thermal, optical, wettability and disintegration in controlled compost properties of the PHB75/PCL25 blend was discussed. Field emission scanning electron microscopy (FESEM) revealed the best dispersion of CNCs on the polymeric matrix was at a load of 3 wt%. Over this loading, CNCs aggregates were formed enhancing the films fragilization due to stress concentration phenomena. However, the addition of CNCs improved the optical properties of the PHB75/PCL25 films by increasing their transparency and accelerated the film disintegration in controlled soil conditions. In general, the blend with 3 wt% CNCs offers the best balanced properties in terms of mechanical, thermal, optical and wettability.

  • 185.
    Garcia-Garcia, Daniel
    et al.
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Balart, Rafael
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Lopez-Martinez, Juan
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Moriana, Rosana
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Optimizing the yield and physico-chemical properties of pine cone cellulose nanocrystals by different hydrolysis time2018Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 5, s. 2925-2938Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanocrystals (CNCs) were isolated for the first time from pine cones (PC) by alkali and bleaching treatments and subsequent sulfuric acid hydrolysis (64%) at 45 degrees C. The influence of the hydrolytic reaction time (30, 45, and 90 min) on the yield, chemical composition and structure, and thermal stability of CNCs was evaluated. The removal of non-cellulosic constituents during the alkaline and bleaching treatment resulted in high pure cellulosic fibres. The isolation of CNCs from these cellulosic fibres at different reaction times was verified by the nano-dimensions of the individual crystals (< 3 and < 335 nm of average diameter and length, respectively). The highest yield (15%) and the optimum CNCs properties in terms of aspect ratio, thermal stability and crystallinity were obtained for an extraction time of 45 min. PC appeared to be a new promising source of cellulose fibres and CNCs with potential to be applied as reinforcement in composites and for food-packaging.

  • 186.
    Gazzotti, Stefano
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimerici LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Adolfsson, Karin H.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ortenzi, Marco Aldo
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimerici LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Farina, Hermes
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimerici LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Lesma, Giordano
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimerici LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Silvani, Alessandra
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimerici LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    One-Pot Synthesis of Sustainable High-Performance Thermoset by Exploiting Eugenol Functionalized 1,3-Dioxolan-4-one2018Ingår i: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 6, nr 11, s. 15201-15211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1,3-Dioxolan-4-one (DOX) chemistry was explored for production of "one-pot" biobased polyester thermosets. DOX monomer was first functionalized by naturally occurring eugenol to introduce a structural element, which could induce cross-linking reaction through cationic polymerization of the double bond. The feasibility of polymerizing DOX monomers bearing bulky side groups was proven by model phenol-substituted DOX monomer (PhDOX). Once the reaction was shown to be effective, the same protocol was applied to eugenol-substituted monomer (EuDOX). A brief screening of the optimal catalyst concentration was performed, to obtain a highly cross-linked product. The synthesized thermoset showed good thermal resistance and high mechanical strength probably due to the rich aromatic content. The obtained thermoset was further subjected to microwave-assisted hydrothermal degradation test, which demonstrated complete recyclability to water or methanol soluble products. NMR and matrix-assisted laser desorption/ionization-mass spectroscopy analyses of the obtained degradation products unveiled the structure of the thermoset, strongly indicating that the polymerization of eugenol-functionalized DOX monomer resulted in polylactide-like chains connected with aromatic aliphatic segments resulting from the reaction of the eugenol double bonds. The presence of free hydroxyl and carboxyl groups sheds light on the mechanism behind the observed shape-memory and self-healing properties.

  • 187.
    Gazzotti, Stefano
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;K;Univ Milan, Dept Chem, CRC Mat Polimer LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Rampazzo, Riccardo
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimer LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bussini, Daniele
    INNOVHUB SSI Paper Dept, Via Giuseppe Colombo 83, I-20133 Milan, Italy..
    Ortenzi, Marco Aldo
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimer LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Farina, Hermes
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimer LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Lesma, Giordano
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimer LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Silvani, Alessandra
    Univ Milan, Dept Chem, Via Golgi 19, I-20133 Milan, Italy.;Univ Milan, Dept Chem, CRC Mat Polimer LaMPO, Via Golgi 19, I-20133 Milan, Italy..
    Cellulose nanofibrils as reinforcing agents for PLA-based nanocomposites: An in situ approach2019Ingår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 171, s. 94-102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One-pot in situ polymerization approach was explored for the preparation of polylactide (PLA)-cellulose nano-fibril (CNF) bio-nanocomposites. CNF were first prepared through enzymatic and mechanical treatment of bleached hardwood kraft pulp. The bio-nanocomposites- were then fabricated through ring opening polymerization (ROP) of L-lactide, in the presence of various amounts of fibrils. Molecular weight, thermal properties, surface morphology, mechanical and wettability properties of the PLA-CNF nanocomposites were evaluated. DSC analysis demonstrated the effect of CNF on crystallization and crystalline morphology of PLA. Improved modulus for the nanocomposites with respect to standard PLA was demonstrated, however, the differences in tensile stress were small probably due to the counteracting effects of reinforcement from CNF and the decreasing molecular weight as a function of CNF concentration. The absence of pulled-out fibers was assessed, highlighting the strong interface and covalent attachment of PLA chains on CNF surface. Finally, the covalent bonding of PLA chains on CNF surface was demonstrated by isolating the non-soluble part, consisting of PLA-grafted CNF, and characterization of this residue.

  • 188.
    Gedde, Ulf W
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lifetime prediction: Different strategies by example2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 233Artikel i tidskrift (Övrigt vetenskapligt)
  • 189. Geng, S.
    et al.
    Yao, Kun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Harila, M.
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Oksman, K.
    Grafting polyethylene glycol on nanocellulose toward biodegradable polymer nanocomposites2017Ingår i: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The reinforcing effect of a small amount of nanocellulose materials on biodegradable and polymer-based nanocomposites remains challenging because of the poor dispersion of the nanomaterials and inefficient interaction between the nanocellulose and the polymer matrix. To improve this, we grafted polyethylene glycol (PEG) on nanocellulose and produced composites of 0.1 wt% nanocellulose materials and polylactic acid (PLA) matrix. Here, two types of PEG grafted nanocellulose including TEMPO-oxidized cellulose nanocrystals (TOCNCs) and cellulose nanofibers (TOCNFs), with different lengths and diameters were used as reinforcements, respectively. We investigated the effects of grafting PEG on microstructure, mechanical properties and thermal behaviors of the PLA/nanocellulose composites. It is found that the PEG grafted nanocellulose dispersed better compared to the unmodified nanocellulose in the PLA matrix, and provides higher reinforcing effect that improves the elastic modulus of the nanocomposites compared to the composites with unmodified nanocellulose and ungrafted PEG. However, the glass transition temperature of the nanocomposites was not improved by grafting PEG significantly. We also found that the nanocomposites reinforced by TOCNF exhibited enhanced mechanical and thermal properties compared to those with TOCNCs, which is caused by the higher aspect ratio of the TOCNFs. 

  • 190.
    Geng, Shiyu
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Luleå Univ Technol, Div Mat Sci, Dept Engn Sci & Math, SE-97187 Luleå, Sweden.
    Yao, Kun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Oksman, Kristiina
    Luleå Univ Technol, Div Mat Sci, Dept Engn Sci & Math, SE-97187 Luleå, Sweden.;Univ Oulu, Fibre & Particle Engn, FI-90014 Oulu, Finland..
    High-Strength, High-Toughness Aligned Polymer-Based Nanocomposite Reinforced with Ultralow Weight Fraction of Functionalized Nanocellulose2018Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 10, s. 4075-4083Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multifunctional lightweight, flexible, yet strong polymer-based nanocomposites are highly desired for specific applications. However, the control of orientation and dispersion of reinforcing nanoparticles and the optimization of the interfacial interaction still pose substantial challenges in nanocellulose-reinforced polymer composites. In this study, poly(ethylene glycol) (PEG)-grafted cellulose nanofibers have demonstrated much better dispersion in a poly(lactic acid) (PLA) matrix as compared to unmodified nanocellulose. Through a uniaxial drawing method, aligned PLA/nanocellulose nanocomposites with high strength, high toughness, and unique optical behavior can be obtained. With the incorporation of 0.1 wt % of the PEG-grafted cellulose nanofibers in PLA, the ultimate strength of the aligned nanocomposite reaches 343 MPa, which is significantly higher than that of other aligned PLA-based nanocomposites reported previously. Moreover, its ultimate strength and toughness are enhanced by 39% and 70%, respectively, as compared to the aligned nanocomposite reinforced with unmodified cellulose nanofibers. In addition, the aligned nanocomposite film is highly transparent and possesses an anisotropic light scattering effect, revealing its significant potential for optical applications.

  • 191.
    Gensch, Marc
    et al.
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany.;Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Ohm, Wiebke
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Brett, Calvin
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Pandit, Pallavi
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Varalil, Sarathlal Koyiloth
    Indian Inst Sci, Dept Phys, Bangalore 560012, Karnataka, India..
    Biessmann, Lorenz
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Kreuzer, Lucas P.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Drewes, Jonas
    Christian Albrechts Univ Kiel, Inst Mat Wissensch, Lehrstuhl Mat Verbunde, Kaiserstr 2, D-24143 Kiel, Germany..
    Polonskyi, Oleksandr
    Christian Albrechts Univ Kiel, Inst Mat Wissensch, Lehrstuhl Mat Verbunde, Kaiserstr 2, D-24143 Kiel, Germany..
    Strunskus, Thomas
    Christian Albrechts Univ Kiel, Inst Mat Wissensch, Lehrstuhl Mat Verbunde, Kaiserstr 2, D-24143 Kiel, Germany..
    Faupel, Franz
    Christian Albrechts Univ Kiel, Inst Mat Wissensch, Lehrstuhl Mat Verbunde, Kaiserstr 2, D-24143 Kiel, Germany..
    Stierle, Andreas
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany.;Univ Hamburg, Phys Dept, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibniz Zentrum MLZ, Lichtenbergstr 1, D-85748 Garching, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany.
    Correlating Nanostructure, Optical and Electronic Properties of Nanogranular Silver Layers during Polymer-Template-Assisted Sputter Deposition2019Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 32, s. 29416-29426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tailoring the optical and electronic properties of nanostructured polymer-metal composites demonstrates great potential for efficient fabrication of modern organic optical and electronic devices such as flexible sensors, transistors, diodes, or photovoltaics. Self-assembled polymer metal nanocomposites offer an excellent perspective for creating hierarchical nanostructures on macroscopic scales by simple bottom-up processes. We investigate the growth processes of nanogranular silver (Ag) layers on diblock copolymer thin film templates during sputter deposition. The Ag growth is strongly driven by self-assembly and selective wetting on the lamella structure of polystyrene-block-poly (methyl methacrylate). We correlate the emerging nanoscale morphologies with collective optical and electronic properties and quantify the difference in Ag growth on the corresponding homopolymer thin films. Thus, we are able to determine the influence of the respective polymer template and observe substrate effects on the Ag cluster percolation threshold, which affects the insulator-to-metal transition (IMT). Optical spectroscopy in the UV-vis regime reveals localized surface plasmon resonance for the metal polymer composite. Their maximum absorption is observed around the IMT due to the subsequent long-range electron conduction in percolated nanogranular Ag layers. Using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy, we identify the oxidation of Ag at the acrylate side chains as an essential influencing factor driving the selective wetting behavior in the early growth stages. The results of polymer-templated cluster growth are corroborated by atomic force microscopy and field emission scanning electron microscopy.

  • 192. Ghaani, M.
    et al.
    Rovera, C.
    Pucillo, F.
    Ghaani, M. R.
    Olsson, Richard T.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Scampicchio, M.
    Farris, S.
    Determination of 2,4-diaminotoluene by a bionanocomposite modified glassy carbon electrode2018Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 277, s. 477-483Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work describes the development of a modified glassy carbon electrode (GCE) for the selective determination of 2,4-diaminotoluene (TDA), a primary aromatic amines (PAAs) that can be formed in food packaging materials including aromatic polyurethane (PU) adhesives. The electrode's surface was modified with multi-walled carbon nanotubes (MWCNTs), MWCNTs in chitosan (CS), and gold nanoparticles (AuNPs). The highest current response was achieved with AuNPs/MWCNTs-CS/GC electrodes, which exhibited an oxidation peak of 9.87 μA by cyclic voltammetry (CV), compared with 1.39 μA of the bare GCE. A detection limit of 35 nM was estimated by amperometry experiments. The oxidation of TDA was strongly dependent on the pH of the medium, having maximum sensitivity at pH ∼ 7. From a mechanistic point of view, the diffusion coefficient of TDA (D = 6.47 × 10−4 cm2 s−1) and the number of electrons (n ≈ 2) involved in the catalytic oxidation of TDA at the surface of the AuNPs/MWCNTs-CS/GCE were determined. The practical utility of this nanocomposite modified electrode was demonstrated by migration studies from conventional food packaging materials. 

  • 193.
    Ghanadpour, Maryam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Phosphorylated Cellulose Nanofibrils: A Nano-Tool for Preparing Cellulose-Based Flame-Retardant Materials2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The growing awareness of the need for a circular society and a circular chemistry has spurred the interest in using wood-based cellulose as a raw material for the preparation of new macroscopic devices and construction materials. The interest has been particularly focused on cellulose nanofibrils (CNF), which has led to the development of new material concepts through a nanoscale bottom-up engineering using renewable CNF. In order to be industrially applicable, the CNF must however possess a set of properties among which good flame-retardation is crucial. This thesis presents a) a way to chemically modify delignified wood fibers by phosphorylation to produce phosphorylated CNF, b) the fabrication and characterization of flame-retardant thin films, coatings and nanocomposite foams from the phosphorylated fibrils and c) the flame-retardant mechanisms of the phosphorylated CNF-based substances.

    Chemically delignified fibers have been phosphorylated by (NH4)2HPO4 in the presence of urea, and the resulting material has been used to prepare phosphorylated CNF (P-CNF). The flame-retardant properties of the phosphorylated fibrils were significantly improved by the phosphorus functionalization of the cellulose chain, converting the fibrils to an inherently flame-retardant material. The P-CNF was applied to make thin films/coatings using the Layer-by-Layer (LbL) technique. All-cellulose free-standing films were prepared through LbL self-assembly of the P-CNF and fibrils prepared from aminated cellulose-rich fibers (cationic CNF). The LbL-assembled film showed a high thermal stability, excellent flame resistance and superior mechanical performance. P-CNF/chitosan (CH) assemblies were also prepared as a fire protection for polyurethane (PU) foams. The five bilayer CH/P-CNF coating yielded a nano-exoskeleton on the surface of PU foam, shown to be capable of increasing the modulus of the foam by a factor of three and entirely preventing its melt dripping during the flammability testing.

    P-CNF/montmorillonite (MMT), sepiolite (Sep) clay or sodium hexametaphosphate (SHMP) films were also fabricated by vacuum filtration/solvent casting of the composite suspensions, and the structural and compositional features of these different films were used to study the mechanisms behind their flame-retardant properties. Only the P-CNF/MMT films were able to completely prevent ignition during cone calorimetry, when used as coatings for highly flammable polyethylene (PE) films and this was mainly ascribed to the excellent barrier properties of these films. The results also showed that the excellent strength and stiffness of the P-CNF/MMT samples, compared to those of the P-CNF/Sep and P-CNF/SHMP films, were essential for maintaining the barrier effect during combustion. Finally, nanostructured foams were prepared by freeze-casting of the P-CNF/Sep suspensions. The foams showed extensive flame-resistance, maintaining a temperature drop of more than 600 °C across the thickness during the flame penetration test. This performance was related mainly to the charring capability of the phosphorylated fibrils combined with the significant thermal insulation of Sep clay.

  • 194.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Carosio, F.
    Ruda, M. C.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Tuning the Nanoscale Properties of Phosphorylated Cellulose Nanofibril-Based Thin Films to Achieve Highly Fire-Protecting Coatings for Flammable Solid Materials2018Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 38, s. 32543-32555Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultrathin nanocomposite films were prepared by combining cellulose nanofibrils (CNFs) prepared from phosphorylated pulp fibers (P-CNF) with montmorillonite (MMT), sepiolite (Sep) clay, or sodium hexametaphosphate (SHMP). The flame-retardant and heat-protective capability of the prepared films as casings for a polyethylene (PE) film was investigated. Heating the coated PE in air revealed that the polymer film was thoroughly preserved up to at least 300 °C. The P-CNF/MMT coatings were also able to completely prevent the ignition of the PE film during cone calorimetry, but neither the P-CNF/Sep nor the P-CNF/SHMP coating could entirely prevent PE ignition. This was explained by the results from combined thermogravimetry Fourier transform infrared spectroscopy, which showed that the P-CNF/MMT film was able to delay the release of PE decomposition volatiles and shift its thermal degradation to a higher temperature. The superior flame-retardant performance of the P-CNF/MMT films is mainly attributed to the unique compositional and structural features of the film, where P-CNF is responsible for increasing the char formation, whereas the MMT platelets create excellent barrier and thermal shielding properties by forming inorganic lamellae within the P-CNF matrix. These films showed a tensile strength of 304 MPa and a Young's modulus of 15 GPa with 10 wt % clay so that this composite film was mechanically stronger than the previously prepared CNF/clay nanopapers containing the same amount of clay. 

  • 195.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, F
    Ruda, M.C.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Flame-retardant nanocomposite thin films based on phosphorylated cellulose nanofibrils: A study of flame-retardant mechanisms2018Ingår i: Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 196.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Wicklein, Bernd
    Carosio, Federico
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    All-natural and highly flame-resistant freeze-cast foams based on phosphorylated cellulose nanofibrils2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 8, s. 4085-4095Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pure cellulosic foams suffer from low thermal stability and high flammability, limiting their fields of application. Here, light-weight and flame-resistant nanostructured foams are produced by combining cellulose nanofibrils prepared from phosphorylated pulp fibers (P-CNF) with microfibrous sepiolite clay using the freeze-casting technique. The resultant nanocomposite foams show excellent flame-retardant properties such as self-extinguishing behavior and extremely low heat release rates in addition to high flame penetration resistance attributed mainly to the intrinsic charring ability of the phosphorylated fibrils and the capability of sepiolite to form heat-protective intumescent-like barrier on the surface of the material. Investigation of the chemical structure of the charred residue by FTIR and solid state NMR spectroscopy reveals the extensive graphitization of the carbohydrate as a result of dephosphorylation of the modified cellulose and further dehydration due to acidic catalytic effects. Originating from the nanoscale dimensions of sepiolite particles, their high specific surface area and stiffness as well as its close interaction with the phosphorylated fibrils, the incorporation of clay nanorods also significantly improves the mechanical strength and stiffness of the nanocomposite foams. The novel foams prepared in this study are expected to have great potential for application in sustainable building construction.

  • 197.
    Ghorbani, Morteza
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning. Mechatronics Engineering Program, Faculty of Engineering and Natural Science, Sabanci University, 34956 Tuzla, Istanbul, Turkey.
    Araz, Sheybani Aghdam
    Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, Istanbul 34956, Turkey.
    Talebian, Moein
    Mechatronics Engineering Program, Faculty of Engineering and Natural Science, Sabanci University, 34956 Tuzla, Istanbul, Turkey.
    Kosar, Ali
    Mechatronics Engineering Program, Faculty of Engineering and Natural Science, Sabanci University, 34956 Tuzla, Istanbul, Turkey ; Sabanci University Nanotechnology Research and Application Center, 34956 Tuzla, Istanbul, Turkey ; Center of Excellence for Functional Surfaces and Interfaces for Nano-Diagnostics (EFSUN), Sabanci University, Orhanli, 34956 Tuzla, Istanbul, Turkey.
    Cakmak Cebeci, Fevzi
    Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, Istanbul 34956, Turkey ; Sabanci University Nanotechnology Research and Application Center, 34956 Tuzla, Istanbul, Turkey.
    Grishenkov, Dmitry
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Svagan, Anna Justina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Facile Hydrodynamic Cavitation ON CHIP via Cellulose Nanofibers Stabilized Perfluorodroplets inside Layer-by-Layer Assembled SLIPS Surfaces2019Ingår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tremendous potential of “hydrodynamic cavitation on microchips” has been highlighted during recent years in various applications. Cavitating flow patterns, substantially depending upon thermophysical and geometrical characteristics, promote diverse industrial and engineering applications, including food and biomedical treatment. Highly vaporous and fully developed patterns in microfluidic devices are of particular interest. In this study, the potential of a new approach, which includes cellulose nanofiber (CNF)- stabilized perfluorodroplets (PFC5s), was assessed inside microfluidic devices. The surfaces of these devices were modified by assembling various sizes of silica nanoparticles, which facilitated in the generation of cavitation bubbles. To examine the pressure effects on the stabilized droplets in the microfluidic devices, the upstream pressure was varied, and the cavitation phenomenon was characterized under different experimental conditions. The results illustrate generation of interesting, fully developed, cavitating flows at low pressures for the stabilized droplets, which has not been previously observed in the literature. Supercavitation flow pattern, filling the entire microchannel, were recorded at the upstream pressure of 1.7 MPa for the case of CNF-stabilized PFC5s, which hardly corresponds to cavitation inception for pure water in the same microfluidic device.

    Publikationen är tillgänglig i fulltext från 2021-09-13 13:48
  • 198.
    Ghorbani, Morteza
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning. Sabanci Univ, Fac Engn & Nat Sci, Mechatron Engn Program, TR-34956 Istanbul, Turkey.
    Olofsson, Karl
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Benjamins, Jan-Willem
    Research Institute of Sweden (RISE), Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden.
    Loskutova, Ksenia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Paulraj, Thomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Grishenkov, Dmitry
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Svagan, Anna Justina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Unravelling the Acoustic and Thermal Responses of Perfluorocarbon Liquid Droplets Stabilized with Cellulose Nanofibers2019Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 35, nr 40, s. 13090-13099Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The attractive colloidal and physicochemical properties of cellulose nanofibers (CNFs) at interfaces have recently been exploited in the facile production of a number of environmentally benign materials, e.g. foams, emulsions, and capsules. Herein, these unique properties are exploited in a new type of CNF-stabilized perfluoropentane droplets produced via a straightforward and simple mixing protocol. Droplets with a comparatively narrow size distribution (ca. 1–5 μm in diameter) were fabricated, and their potential in the acoustic droplet vaporization process was evaluated. For this, the particle-stabilized droplets were assessed in three independent experimental examinations, namely temperature, acoustic, and ultrasonic standing wave tests. During the acoustic droplet vaporization (ADV) process, droplets were converted to gas-filled microbubbles, offering enhanced visualization by ultrasound. The acoustic pressure threshold of about 0.62 MPa was identified for the cellulose-stabilized droplets. A phase transition temperature of about 22 °C was observed, at which a significant fraction of larger droplets (above ca. 3 μm in diameter) were converted into bubbles, whereas a large part of the population of smaller droplets were stable up to higher temperatures (temperatures up to 45 °C tested). Moreover, under ultrasound standing wave conditions, droplets were relocated to antinodes demonstrating the behavior associated with the negative contrast particles. The combined results make the CNF-stabilized droplets interesting in cell-droplet interaction experiments and ultrasound imaging.

  • 199.
    Ghorbani, Morteza
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Svagan, Anna Justina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Grishenkov, Dmitry
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Karolinska Institutet (KI), CLINTEC – Division of Medical Imaging and Technology.
    Acoustic Response of a Novel Class of Pickering Stabilized Perfluorodroplets2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Introduction

    Acoustic Droplet Vaporization (ADV) is a phase change phenomenon in which the liquid state, in the form of droplets, is converted to gas as a result of bursts in the excited ultrasound field. Having a wide range of medical applications, ADV has drawn considerable attention in imaging [1], diagnosis and critical medical treatment [2]. Therefore, benefitting from its broad potentials, with the consideration of its capability in localized noninvasive energy exposure, it is possible to utilize its effect in different medical applications from targeted drug delivery [3] to embolotherapy [4].

    Apart from the droplet characterization and ADV effectiveness on the applied region, the physics of ADV and particularly the ultrasound analysis is an essential parameter in the initiation of the vaporization. This part, which is related to acoustic wave physics, implies that ADV is mostly dependent on ultrasound pressure, frequency and temperature. In this sense, Miles et al. [5] tried to find incident negative pressure - called as ADV threshold- which is necessary for the induction of nucleation. It was successfully shown that the negative pressure required for the nucleation prior to collapse can be determined via perturbation analysis of a compressible inviscid flow around a droplet for various frequencies and diameters. In addition, the fluid medium which constitutes the droplet emulsion and the surrounding fluid constructs a significant field within ADV. In this regard, there are many studies which illustrated that the diameter of the droplets subjected to the acoustic waves undergoes a significant expansion of 5 to 6 times of their regular sizes [6-8].

    In this study, a new type of pickering stabilized perfluorodroplets (PFC) was examined under the effect of the different acoustic parameters to evaluate its potential in the acoustic droplet vaporization process. To assess the pressure effects on the stabilized droplets, the acoustic power within the ultrasound tests was varied and the phase trasnition was characterized according to the experimental conditions. Opticell® was utilized as the transparent device to visualize the droplets, which were exposed to the acoustic waves with the aid of the microscope and multi-well microplate.

    Methods

    Materials and emulsion preparation

    Perfluoropentane (PFC5) was purchased from Apollo Scientific (City, U.K.). Bleached sulfite pulp (from Nordic Paper Seffle AB, Sweden) was used in the production of the cationic cellulose nanofibers (CNFs). The CNF suspension (1.32 wt%) were prepared as described previously [9]. The CNFs had a dimension of 3.9 ± 0.8 nm in width and a length in the micrometer range. The amount of cationic groups was 0.13 mmol per g fiber, obtained from conductometric titration [9]. A suspension of CNF (0.28 wt%) was prepared by diluting the stock CNF with MilliQ-water (pH of diluted CNF suspension was 9.5). The suspension was treated with ultra-sonication at amplitude of 90% for 180 s (Sonics, Vibracell W750). The suspension was brought to room temperature. An amount of 36 g of the 0.28 wt% CNF suspension was mixed with 1 g of PFC5. The mixture was sonicated for 60s at an amplitude of 80% (under ice-cooling) to obtain the CNF-stabilized PFC5 droplets.

    The protocol for the acoustic tests

    100 μL of CNF-stabilized PFC5 droplets were added to 1900 μL of deionized water in order to prepare the solution which were exposed to the ultrasound waves. The droplet sample, diluted 1:19 in distilled water was introduced to the Opticell® and the acoustic waves at a fixed frequency and different powers were applied to the trageted area inside the Opticell® which is located inside a water bath. The ultrasound triggered sample then was placed under a 20X magnification objective of upright transmitted light microscope (ECLIPSE Ci-S, Nikon, Tokyo, Japan). 

    The acoustic tests were performed using high-power tone burst pulser-receiver (SNAP Mark IV,  Ritec, Inc., Warwick, RI, USA) equipped with a transducer (V382-SU Olympus NDT, Waltham, MA ) operating at the frequency of 3.5 MHz. The emulsion of CNF-stabilized PFC5 droplets were exposed to the power range which has the acsending trend from -30 to 0 dB at the given frequency. To investigate the droplet size variations at each power between, the droplets were collected inside the Opticell® and the droplet diameter was measured with the aid of the ImageJ software (version 1.50b, National institutes of health, USA) to determine the concentration and size distribution. The Gaussian distribution is ploted with mean value and standad deviation recover from the experimental data. An in-house image edge detection MATLAB™ script (MathWorks Inc., Natick, MA) were applied to analyze the images obtained from the microscope and provides the size and volume distributions.

    Results

    The size of PFP droplets is an important parameter to controll in the therapeutic applications. Here, a new type of Pickering stabilized perfluorodroplets were prepared where the PFP/water interface was stabilized with cellulose nanofibers (CNF) and the size of the droplets could easily be controlled by varying the amount of CNF added.  The resulting droplets were investigated using a single crystal transducer. Apart from the medical applications, controlling the droplet size is important from droplet dynamics point of view, becausethe interfacial energy is crucial in the assumption of the critical nucleus radius. Therefore, it is possible to estimate the negative peak pressure required for the phase transition once the droplet is controlled and interfacial energy deposited inside and on the surface of the droplet are balanced.

    According to the results in Figure 1, there is an appreciable rise of the size of the droplets after ultrasound waves exposure, particularly at -8 dB power. The experiments were performed for 30 seconds at different powers ranging from -30 to 0 dB, while the frequency was kept constant at 3.5 MHz, burst width in cycles was selected as 12 and repetition rate was set to 100. Images included in Figure 1 demonstrate major transitions in the intervals at -16, -8 and 0 dB. As shown in this figure, the droplet size increased with the power rise and more bubbles with bigger sizes appears at higher powers. This outcome implies the significant role of the applied frequency and power on the phase shift and subsequent mechanisms as a result of the acoustic wave exposure on the new nontoxic and incompatible droplet type.

    Figure 2 shows the average number of droplets and volume distribution at the corresponding powers to the Figure 1. It is shown that while the average diameter of the droplets is around 3.5 µm, the generated bubbles, as a result of the ADV, reaches up to 15 µm at the highest possible power. For each set of experiment (corresponding to a given power) 32 images were taken, thus, to reduce the errors and obtain the standard deviation (approximately 0.8 for all the cases), the presented diagrams for the droplet distributions exhibits the mean value for all of the acquired images. Therefore, it is shown that the droplet emulsion exhibited in NO US in Figure 2, which shows the regular view and distribution range of the CNF-stabilized PFC5 droplets at the room temperature, experiences ADV process with the diameter rise of about 5 times at the highest power when the frequency is fixed at 3.5 MHz.

    Conclusions

    The results show that there is appreciable rise on the size of the droplets after ultrasound waves exposure at a fixed frequency. Acoustic droplet vaporization (ADV) was illustrated at different powers for CNF-stabilized PFC5 droplets as a new class of pickering stabilized perfluorodroplets with the increase in the size of the droplets and following phase trasition to bubbles. Diameter increase of 5 times were obtained after the ultrasound exposure indicating the efficiency of the suggested droplets for the ADV process and therapeutic applications.   

    References

    [1] Arena CB, Novell A, Sheeran PS, Puett C, Moyer LC, Dayton PA, Dual-Frequency Acoustic Droplet Vaporization Detection for Medical Imaging 2015, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 62: 9.

    [2] Kripfgans OD, Fowlkes JB, Miller DL, Eldevik OP, Carson PL, Acoustic droplet vaporization for therapeutic and diagnostic applications 2000, Ultrasound Med. Biol, 26:1177–1189.

    [3] Kang ST, Yeh CK, Intracellular Acoustic Droplet Vaporization in a Single Peritoneal Macrophage for Drug Delivery Applications 2011, Langmuir, 27:13183–13188.

    [4] Zhu M, Jiang L, Fabiilli ML, Zhang A, Fowlkes JB, Xu LX, Treatment of murine tumors using acoustic droplet vaporization-enhanced high intensity focused 2013, Ultrasound Phys. Med. Biol, 58:6179–6191.

    [5] Miles CJ, Doering CR, Kripfgans OD, Nucleation pressure threshold in acoustic droplet vaporization 2016, Journal of Applied Physics, 120:034903.

    [6] Sheeran PS, Wong VP, Luois S, McFarland RJ, Ross WD, Feingold S, Matsunaga TO, Dayton PA, Decafluorobutane as a phase-change contrast agent for low-energy extravascular ultrasonic imaging 2011, Ultrasound Med. Biol, 37:1518–1530.

    [7] Kripfgans OD, Fowlkes JB, Miller DL, Eldevik OP, Carson PL, Acoustic droplet vaporization for therapeutic and diagnostic applications 2000, Ultrasound Med. Biol, 26:1177–1189.

    [8] Kang S, Huang Y, Yeh C, Characterization of acoustic droplet vaporization for control of bubble generation under flow conditions 2014, Ultrasound Med. Biol, 40:551–561.

    [9] Svagan AJ, Benjamins JW, Al-Ansari Z, Shalom DB, Müllertz A, Wågberg L, Löbmann K, Solid cellulose nanofiber based foams–towards facile design of sustained drug delivery systems 2016, J. Control Release, 244:74–82 (Part A).

     

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  • 200.
    Ghorbani, Morteza
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Svagan, Anna Justina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Grishenkov, Dmitry
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Targeted Hydrodynamic Cavitating Flows via Ultrasound Waves via Pickering Stabilized Perfluorodroplets2020Konferensbidrag (Refereegranskat)
    Ladda ner fulltext (pdf)
    fulltext
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