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  • 101. Eldsäter, Carina
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    Effect of abiotic factors on the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in simulated and natural composting environments1999In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, no 2, p. 177-183Article in journal (Refereed)
  • 102. Erlandsson, Bengt
    et al.
    Albertsson, Ann-Christine
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Molecular weight determination in degraded oxidizable and hydrolyzable polymers giving deviation from accurate using calibration and the Mark-Houwink-Sakaruda (MHS) equation1997In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 57, no 1, p. 15-23Article in journal (Refereed)
  • 103. Erlandsson, Bengt
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    Correlation between molecular weight changes and 14CO2 evolution from biodegraded 14C-labelled ethylene-vinyl alcohol copolymer and ethylene polymer1998In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 49, p. 363-Article in journal (Refereed)
  • 104. Erlandsson, Bengt
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    The mode of action of corn starch and a pro-oxidant system in LDPE: influence of thermooxidation and UV-irradiation on the molecular weight changes1997In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 55, no 2, p. 237-245Article in journal (Refereed)
  • 105.
    Fagerland, Jenny
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Synthesis and Characterization of Self-Assembling Low Molecular Weight Copolymers for Bioengineering Applications2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The constant need for improved biomedical materials and the interest in producing materials with similar properties to the extracellular matrix in different tissues has resulted in increasing interest in research on hydrogels. Over the last decade self-assembling copolymers have been of particular interest since they form hydrogels in response to external stimuli such as temperature. In this thesis, two self-assembling low molecular weight copolymers; poly(L-lactide-co-glycolide) grafted with poly(ethylene glycol) methyl ether (PLGA-g-MPEG) and poly(L-lysine-co-L-alanine) (poly(Lys-co-Ala)) were synthesized for possible bioengineering applications. Their chemical structure and composition was analysed by nuclear magnetic resonance spectroscopy (NMR) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The results showed that low molecular weight PLGA-g-MPEG and poly(Lys-co-Ala) were successfully obtained.

    PLGA-g-MPEG hydrogels were formed at 37°C, within 1 minute, at a pH between 6-7 and had a functional life of one month. The block cooligopeptides of L-lysine and L-alanine formed cubic, hexagonal and hollow crystals in low pH and irregularly shaped crystals in at pH 7, while plate-like crystals were formed at both pH 3 and 7 form the random cooligopeptides. Evaluation of the properties of the low molecular weight copolymers, such as pH, functional life and crystalline morphology, revealed that the chemical composition and solvent composition strongly affects their self-assembling properties.

    These synthesized low molecular weight copolymers showed promise results for use as material in biomedical applications. Areas of potential use for these materials include bioengineered hierarchical scaffold material facilitating sequential release of growth factors, for example in bone tissue engineering, and as materials for encapsulated drug delivery.

  • 106.
    Fagerland, Jenny
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Synthesis of degradable aliphatic polyesters: strategies to tailor the polymer microstructure2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Key factors for successful tissue engineering are the synthesis and design of the scaffold materials. Aliphatic polyesters have been studied and often used as scaffold materials for tissue engineering. However, their lack of biological cues and degradation under high-temperature processing (e.g., 3D printing) are a limitation. In this thesis, different synthesis strategies are presented which has the potential to improve the performance of aliphatic polyesters as scaffolds for tissue regeneration.

    To stimulate interactions between exogenous materials and the surrounding tissue, two different strategies were applied. Either, by designing a two component system in which the different degradation profiles of the polymers allow for sequential release of growth factors. Or, by peptide functionalization of an aliphatic polyester chain using template-assisted chemo-enzymatic synthesis. The results from the studies were successful. A hierarchical system was obtained in which the poly(L-lactide-co-glycolide)-graft-poly(ethylene glycol) methyl ether (PLGA-g-MPEG), hydroxyapatite solution formed a gel around and within the pores of the poly(L-lactide-co-ε-caprolactone) scaffold at 37 ºC, within 1 min, that was stable for 3 weeks. The peptide functionalization was also successful where an aliphatic polyester of L-lactide was functionalized with different oligopeptides using a grafter (ethyl hept-6-enoylalaninate) and chemo-enzymatic synthesis.

    The thermal properties of poly(L-lactide-co-hydroxybutyrate) were tailored (by modification of the microstructure) to potentially improve the processability of the aliphatic polyester.  The results showed that the yttrium salan catalyst was the most successful, yielding high molecular weight copolymers in shorter time. They also showed that the Tg could be tailored by varying the amount of rac-β-butyrolactone in the copolymer to better suit thermal processing techniques, such as 3D printing.

  • 107.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Mapping the synthesis and the impact of low molecular weight PLGA-g-PEG on sol-gel properties to design hierarchical porous scaffolds2013In: Journal of polymer research, ISSN 1022-9760, E-ISSN 1572-8935, Vol. 21, no 1, p. 337-Article in journal (Refereed)
    Abstract [en]

    Bone morphogenetic protein 2 (BMP-2)-functionalized poly(l-lactide-co-epsilon-caprolactone) (PLCL) porous scaffolds have shown promising results in bone tissue regeneration studies. It is believed that even better results are achieved by hierarchical porous scaffolds and a designed sequential release of growth factors. We therefore synthesized (l-lactide-co-glycolide)-g-poly(ethylene glycol) (PLGA-g-PEG) oligomers which could be injected into PLCL porous scaffolds. They were synthesized by ring-opening polymerization and carefully characterized by nuclear magnetic resonance spectroscopy (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The sol-gel transition temperature, pH, and functional life were determined and correlated with the molecular structure of PLGA-g-PEG. We found that low molecular weight PLGA-g-PEG was obtained and poly(l-lactide-co-glycolide-co-poly(ethylene glycol) methyl ether) (PLGA-MPEG) appeared to contribute to gelation. It was possible to design a system that formed a hydrogel within 1 min at 37 A degrees C with a pH between 6 and 7 and with a functional life of around 1 month. These low molecular weight thermosensitive PLGA-g-PEG oligomers, which can be injected into PLCL scaffolds, appear promising for bone tissue engineering applications.

  • 108.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Numata, Keiji
    Short One-Pot Chemo-Enzymatic Synthesis of L-Lysine and L-Alanine Diblock Co-Oligopeptides2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 3, p. 735-743Article in journal (Refereed)
    Abstract [en]

    Amphiphilic diblock co-oligopeptides are interesting and functional macromolecular materials for biomedical applications because of their self-assembling properties. Here, we developed a synthesis method for diblock co-oligopeptides by using chemo-enzymatic polymerization, which was a relatively short (30 min) and efficient reaction (over 40% yield). Block and random oligo(L-lysine-co-L-alanine) [oligo(Lys-co-Ala)] were synthesized using activated papain as enzymatic catalyst. The reaction time was optimized according to kinetic studies of oligo(L-alanine) and oligo(L-lysine). Using H-1 NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we confirmed that diblock and random co-oligopeptides were synthesized. Optical microscopy further revealed differences in the crystalline morphology between random and block co-oligopeptides. Plate-like, hexagonal, and hollow crystals were formed due to the strong impact of the monomer distribution and pH of the solution. The different crystalline structures open up interesting possibilities to form materials for both tissue engineering and controlled drug/gene delivery systems.

  • 109.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Numata, Keiji
    Short one-pot chemo-enzymatic synthesis of L-lysine and L-alanine diblock copolypeptidesManuscript (preprint) (Other academic)
  • 110.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology. University of Sannio, Italy.
    Schmidt, Björn
    KTH, School of Biotechnology (BIO), Protein Technology.
    Syrén, Per-Olof
    KTH, School of Biotechnology (BIO), Protein Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Template-assisted enzymatic synthesis of oligopeptides from a polylactide chain2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 12, p. 4271-4280Article in journal (Refereed)
    Abstract [en]

    Peptides are often attached to polymer materials, as bioactive components, for the control of interactions between the material and its surrounding proteins and cells. However, synthesizing peptides and attaching them to polymers can be challenging and laborious. Herein, we describe the grafting of oligopeptides to an aliphatic polyester, using a one-step chemo-enzymatic synthesis with papain as the biocatalySt. To enable enzyme-mediated functionalization of the polyester, ethyl hept-6-enoylalaninate (grafter) was synthesized and attached to polylactide chains using thiol-ene click reactions. The oligopeptides were grafted onto the polylactide chains using two different synthetic routes: the grafting from strategy, in which the grafter was attached to the polyester prior to oligopeptide synthesis, or the grafting to strategy, in which oligopeptides were synthesized on the grafter first, then attached to the polymer chain. The final products were analyzed and their structures were confirmed using nuclear magnetic resonance (NMR). The peptide attachment was evaluated using size exclusion chromatography (SEC), contact angle measurement and energy-dispersive X-ray spectroscopy scanning electron microscopy (EDS-SEM). Furthermore, the mechanistic aspects of the synthesis of the oligopeptides on the grafter were studied using molecular dynamics (MD) simulations. The simulation revealed that hydrogen bonding (between the P1 amide nitrogen of the grafter backbone and the carbonyl oxygen of D158 in the papain) maintain the grafter in a productive conformation to stabilize the transition state of nitrogen inversion, a key step of the biocatalytic mechanism. Apart from being biologically relevant, both experimental and computational results suggest that the designed grafter is a good template for initiating chemo-enzymatic synthesis. The results also showed that the grafting to strategy was more successful compared to the grafting from strategy. Overall, a successful synthesis of predefined peptide functionalized polylactide was prepared, where the oligopeptides were grafted in an easy, time efficient, and environmentally friendly way.

  • 111.
    Finne Wistrand, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Polylactide:  2011In: Handbook of Engineering and Speciality Thermoplastics: Polyethers and Polyesters / [ed] S. Thomas and V. P.M., Hoboken, NJ, USA: John Wiley & Sons, 2011, p. 349-376Chapter in book (Other academic)
    Abstract [en]

    The production of durable functional products without using petroleumbased raw materials is a focus of much academic research today but it is also prioritized by many industries. Many questions still remain concerning the use, production and properties of bio-based and/or degradable polymers and whether or not they are more environmentally friendly than oil-based products. Polylactide is a bio-based compostable thermoplastic that is considered as one of the most promising materials for replacement of traditional volume plastics. The properties of polylactide can be tuned to resemble polystyrene, poly(ethylene terephthalate) or polyolefins by controlling the stereochemistry by copolymerization or blending. This chapter reviews the life-cycle of polylactide based materials as well as the properties and applications. The recent trends in the area are also discussed.

  • 112. Finnveden, G
    et al.
    Albertsson, A-C.
    Berendson, J.
    Eriksson, E.
    Höglund, L-O.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sundquist, J-O.
    Solid waste treatment within the framework of life-cycle assessment1995In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 3, p. 189-Article in journal (Refereed)
  • 113. Gallet, G.
    et al.
    Lämpiänen, R.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Characterisation by SPME-GC-MS of matrix changes of poly(L-lactide) exposed to outdoor soil environment2001In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 71, p. 147-Article in journal (Refereed)
  • 114.
    Gedde, Ulf W
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Richard Hays Boyd in memorial2017In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 118, p. 305-306Article in journal (Refereed)
  • 115.
    Glavas, Lidija
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    From Macromolecular Design to Supramolecular Self-assembly2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Advancements in drug delivery have enabled a wider array of prevention, control and treatment of diseases such as cancer. Drug delivery systems have the possibility of encapsulating drugs with low solubility, delivering them to specific locations in the body as well as obtaining a controlled and sustained drug release. The systems used today range over a wide structural and compositional area, where liposomes as well as nanotubes have been used as vehicles. Polymeric micelles also play an important role as drug carriers and have gathered great attention due to their versatility.

    The optimization of these micelle systems is critical in order to enhance their effect. In this work three strategies were designed for the tailoring of micelle behavior in order to induce desirable and controllable micelle properties.

    The influence of polymer architecture upon self-assembly was facilitated by designing a novel synthetic pathway yielding cyclic polypeptides. The initiation route using amidine or guanidine bases induced zwitterionic polymerization and hence resulted in cyclic polypeptides. A strategy using the crystallinity of the micelle core to tailor micelle behavior was accomplished. By solely using the core crystallinity, tuning of the critical micelle concentration, micelle size as well as loading and release of hydrophobic molecules was achieved. The induction of redox-responsiveness and electroactivity, through the introduction of aniline pentamer into amphiphilic PEG-PLA, gave rise to time-dependent dissociation (triggered release) of the micelles without external stimuli.

    A powerful toolbox has been created for the tailoring of micelle behavior. By combining these tools, the design of optimized drug carriers for specific applications is enabled.

  • 116.
    Glavas, Lidija
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Guo, Baolin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Tuned electrical conductivity by macromolecular architecture: Electroactive and degradable block copolymers based on polyesters and aniline oligomers2012In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 244Article in journal (Other academic)
  • 117.
    Glavas, Lidija
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Induced redox responsiveness and electroactivity for altering the properties of micelles without external stimuli2014In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 10, no 22, p. 4028-4036Article in journal (Refereed)
    Abstract [en]

    Control over micelle properties is vital in the field of drug delivery, and the ability to modify these properties in order to trigger dissociation is highly desirable. We prepared polymeric micelles with the ability to undergo dissociation over time without the need for external stimulation by incorporating an electroactive and redox responsive segment into amphiphilic copolymers. The incorporation of this segment also provides the ability to tailor the critical micelle concentration (CMC) and micelle size of the copolymers. Amphiphilic PEG-PLA copolymers were functionalized by coupling to an aniline pentamer in two different oxidation states (leucoemeraldine and emeraldine state). The incorporation of the electroactive and redox responsive aniline pentamer decreased the CMCs and the micelle size, independent of the oxidation state. However, the copolymers with the aniline pentamer in the leucoemeraldine state had significantly lower CMCs than the copolymers with the aniline pentamer in the emeraldine state. Simultaneously, stability tests performed on the functionalized micelles demonstrated the oxidation of the aniline segment, from the leucoemeraldine to the emeraldine state, over time. The oxidation led to an increase in the CMC, and the copolymers could thereby represent an excellent starting point for triggering drug release without external stimuli.

  • 118.
    Glavas, Lidija
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Redox responsiveness and electroactivity for preparation of smart micelles2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248Article in journal (Other academic)
  • 119.
    Glavas, Lidija
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Olsén, Peter
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Achieving Micelle Control through Core Crystallinity2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 11, p. 4150-4156Article in journal (Refereed)
    Abstract [en]

    We have designed a pathway for controlling the critical micelle concentration and micelle size of polyester-based systems. This was achieved by creating an array of different copolymers with semicrystalline or amorphous hydrophobic blocks. The hydrophobic block was constructed through ring-opening polymerization of epsilon-caprolactone, L-lactide, and epsilon-decalactone, either as homopolymers or random copolymers, using PEG as both the initiator and the hydrophilic block. Micelles formed with amorphous cores exhibited considerably higher critical micelle concentrations than those with semicrystalline cores. Micelles with amorphous cores also became larger in size with an increased molecular weight of the hydrophobic bock, in contrast to micelles with semicrystalline cores, which displayed the opposite behavior. Hence, core crystallinity was found to be a potent tool for tailoring micelle properties and thereby facilitating the optimization of drug delivery systems. The introduction of PEG-P epsilon DL also proved to be a valuable asset in the tuning of micelle properties.

  • 120. Golda-Cepa, M.
    et al.
    Aminlashgari, Nina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Engvall, Klas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kotarba, A.
    LDI-MS examination of oxygen plasma modified polymer for designing tailored implant biointerfaces2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 50, p. 26240-26243Article in journal (Refereed)
    Abstract [en]

    A versatile polymer coating for biomaterials was fabricated by the mild oxygen plasma treatment of Chemical Vapour Deposited (CVD) parylene C. The surface properties were tailored while the excellent protective properties of the bulk were preserved. The species, formed due to the plasma functionalisation, were fingerprinted by a novel Laser Desorption/Ionisation-Mass Spectrometry (LDI-MS) method. Improved osteosarcoma cells (line MG-63) attachment and viability on a modified surface were demonstrated.

  • 121. Golda-Cepa, M.
    et al.
    Brzychczy-Wloch, M.
    Engvall, Klas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Aminlashgari, Nina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kotarba, A.
    Microbiological investigations of oxygen plasma treated parylene C surfaces for metal implant coating2015In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 52, p. 273-281Article in journal (Refereed)
    Abstract [en]

    Parylene C surface was modified by the use of oxygen plasma treatment and characterized by microscopic and surface-sensitive techniques (E-SEM, AFM, XPS, LDI-TOF-MS, contact angle). The influence of the treatment on surface properties was investigated by calculations of surface free energy (Owens-Wendt method). Moreover, early adhesion (Culture Plate Method, Optical Microscopy Test) and biofilm formation ability (Cristal Violet Assay) on the parylene C surface was investigated. The bacteria strains which are common causative agents of medical device-associated infections (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa - reference strains and clinical isolates) were used. It was concluded that chemical (oxygen insertion) and physical (nanotopography generation) changes, have a significant impact on the biocompatibility in terms of increased hydrophilicity (θw of unmodified sample = 88° ± 2°, θw of 60 min modified sample = 17.6° ± 0.8°) and surface free energy (SFE of unmodified sample = 42.4 mJ/m2, and for 60 min modified sample = 70.1 mJ/m2). At the same time, no statistical effect on biofilm production and bacteria attachment to the modified surface of any of the tested strains was observed.

  • 122.
    Gröning, Mikael
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Polymer Recycling and Degradation2005In: McGraw-Hill Yearbook of Science and Technology 2005, New York: McGraw-Hill, 2005, p. 268-271Chapter in book (Other academic)
  • 123.
    Guerzoni, Samuele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Deplaine, Harmony
    El Haskouri, Jamal
    Amoros, Pedro
    Monleon Pradas, Manuel
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Gallego Ferrer, Gloria
    Combination of silica nanoparticles with hydroxyapatite reinforces poly (L-lactide acid) scaffolds without loss of bioactivity2014In: Journal of bioactive and compatible polymers (Print), ISSN 0883-9115, E-ISSN 1530-8030, Vol. 29, no 1, p. 15-31Article in journal (Refereed)
    Abstract [en]

    Composite scaffolds of poly(l-lactide acid) and hydroxyapatite are of great interest in bone tissue engineering, but their mechanical properties are typically inferior to scaffolds of pure poly(l-lactide acid) due to agglomeration of the particles and weak interfacial component interaction. Fabrication strategies like double sonication of hydroxyapatite or increasing the amount of this inorganic filler do not effectively enhance the mechanical performance. In this study, poly(l-lactide acid) composites combining two types of fillers, mesoporous silica (SiO2) nanoparticles and hydroxyapatite, were developed to reinforce the poly(l-lactide acid) scaffold without any loss of bioactivity. A 5% addition of SiO2 nanoparticles to hydroxyapatite nanopowder and subjecting the scaffold formulation to double sonication increased the Young's modulus from 5 MPa (pure poly(l-lactide acid) scaffold) to almost 7 MPa (poly(l-lactide acid)/hydroxyapatite/SiO2 scaffold). In addition, the composite was able to deposit a layer of biomimetic hydroxyapatite both on the surface and interior of the scaffold after 21 days of immersion in a simulated body fluid. The manufacturing method was straightforward and economically viable and does not require any chemical modification of the particles' surfaces.

  • 124.
    Guo, Baolin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    degradable electroactive polymers: Synthesis, Macromolecular architecture and scaffold design2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electrically conducting polymers induce specific cellular responses at the molecular level. One of the crucial limitations of the use of conducting polymers in tissue engineering is their inability to degrade. The incorporation of conductivity into degradable polymers to obtain materials that are both electroactive and degradable is therefore highly anticipated. Architecture plays an important role in the performance of polymers. To be able to achieve the optimal mechanical, degradation, thermal and biological properties for a particular biomedical application, it is desirable to promote architectural diversity.

     In the first part, by combining the electroactivity of conducting polymers and the degradability of aliphatic polyesters, we have designed and synthesized a series of linear, star-shaped, hyperbranched, and crosslinked degradable and electrically conducting polymers and hydrogels based on polylactide (PLA), polycaprolactone (PCL), and aniline oligomers such as aniline trimer, aniline tetramer, and aniline pentamer. The polymers and hydrogels obtained have good electroactivity, as indicated by their ultraviolet spectra and by cyclic voltammetry. The conductivities of the polymers and hydrogels are tuned by the content of the aniline oligomer and the macromolecular architecture. The hydrophilicity of the polymers was greatly increased after doping the aniline oligomer with acid, which overcomes the hydrophobicity of the PLA and PCL. Thermogravimetric analysis and differential scanning calorimetry studies show that these copolymers and hydrogels have good thermal properties compared to PLA and PCL. The swelling ratios of these hydrogels covered a wide range and were controlled by the degree of crosslinking, the oligoaniline content, and the pH of the surrounding solution.

     In the next part, methods for the facile synthesis of degradable conducting polymers and hydrogels were presented to avoid the multi-step reaction used in the earlier work. We developed a one-pot reaction for the synthesis of degradable conducting polysaccharide hydrogels based on chitosan and aniline tetramer. These hydrogels can form free-standing and flexible conducting films. This overcomes the drawback of polyaniline which could not be easily fabricated into a thin film in common organic solvents. We also presented a universal two-step approach to create degradable conductive diblock or triblock copolymers based on a polyester and aniline tetramer or aniline pentamer by a combination of ring opening polymerization and post-functionalization via an oxidative coupling reaction. The self-assembly behavior of the triblock copolymer consisting of a middle aniline pentamer segment and two bilateral polycaprolactone segments in chloroform as a selective solvent (selective for PCL segment) were also investigated by transmission electron microscopy and dynamic light scattering. The size of the nanoparticles from the assembly of the triblock copolymers depends on the molecular weight of the copolymer and on the aniline pentamer state.

     In the last part, electroactive degradable non-toxic porous tubular scaffolds were fabricated from a polymer blend of hyperbranched degradable conductive copolymer and PCL by a modified solution-casting/particle-leaching technique. The porous structure of the tubular scaffolds was investigated by scanning electron microscope and microcomputed tomography. The hydrophilicity of the blend films was greatly improved by doping with (±)-10-camphorsulfonic acid. The conductivity of the films was tuned by adjusting the ratio of hyperbranched degradable conducting copolymer to PCL. The cytotoxicity test with HaCaT keratinocytes indicated that the materials were non-toxic.

     These degradable electroactive copolymers and hydrogels with different architectures and properties have a great potential for meeting the requirements of biomedical application.

  • 125.
    Guo, Baolin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Synthesis, characterization and molecular architecture of electroactive and degradable polymers2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The third-generation biomaterials are designed to stimulate specific cellular responses at the molecular level. Recent studies have shown that electrical signals regulate cellular activities including cell adhesion, migration, proliferation and differentiation. One of the biggest limitations for conductive polymers in tissue engineering applications is their inherent inability to degrade, so the incorporation of conducting polymers into biodegradable polymers to obtain electroactive and biodegradable materials is still a challenge. Architecture plays an important role on the performance of polymers. To achieve the optimal mechanical, degradation, thermal and biological properties for each biomedical application, it is desirable to promote architectural diversity.

     

    To combine the electroactivity of conductive polymers and the degradability of aliphatic polyesters, linear, star-branched and hyperbranched copolymers based on Poly(L,L-lactide) (PLLA), Poly(ε-caprolactone) (PCL), and aniline oligomers were synthesized by coupling reactions between the hydroxyl group at the chain end of the PLLAs or PCLs and the carboxyl group of the aniline oligomer, using the N, N’-dicyclohexyl carbodiimide / 4-dimethylaminopyridine (DCC/DMAP) catalytic system. The chemical structures of the polymers obtained were fully characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and size exclusion chromatography. The cyclic voltammetry and ultraviolet spectra of the copolymers demonstrated their good electroactive properties. Differential scanning calorimetry and thermogravimetric analysis studies showed the copolymers were more thermal stable than the corresponding PLLAs and PCLs. The wettability of the copolymer film increased sharply after doping with acid. The copolymers also exhibit much better processibility than conductive polymers because they are soluble in most organic solvents.

     

    Macromolecular architecture design as a useful tool to enhance the conductivity of degradable polymers has been presented. The hyperbranched copolymers showed a higher conductivity than that of the linear ones with the same content of conductive segments. It is proposed that the higher conductivity of the hyperbranched copolymers is due to the ordered distribution of peripheral emeraldine state of aniline pentamer (EMAP) segments. Thus, the conductivity of the polymers is controlled by the macromolecular design. In other words, the conductivity of the polymers was increased with the same content of aniline oligomer by macromolecular architecture.

    The copolymers with different architectures could be used to tailor the thermal properties, degradation properties and surface properties, to give materials that are favorable for the growth of electrically excitable cells in tissue engineering.

  • 126.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Molecular Achitecture of electroactive and biodegradable copolymers composed of polyactide and carboxyl-capped aniline trimer2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 4, p. 855-863Article in journal (Refereed)
    Abstract [en]

    wo-, four-, and six-armed branched copolymers with electroactive and biodegradable properties were synthesized by coupling reactions between poly(l-lactides) (PLLAs) with different architecture and carboxyl-capped aniline trimer (CCAT). The aniline oligomer CCAT was prepared from amino-capped aniline trimer and succinic anhydride. FT-IR, NMR, and SEC analyses confirmed the structure of the branched copolymers. UV−vis spectra and cyclic voltammetry of CCAT and copolymer solution showed good electroactive properties, similar to those of polyaniline. The water contact angle of the PLLAs was the highest, followed by the undoped copolymer and the doped copolymers. The values of doped four-armed copolymers were 54−63°. Thermal properties of the polymers were studied by DSC and TGA. The copolymers had better thermal stability than the pure PLLAs, and the Tg between 48−58 °C and Tm between 146−177 °C of the copolymers were lower than those of the pure PLLA counterparts. This kind of electroactive and biodegradable copolymer has a great potential for applications in cardiovascular or neuronal tissue engineering.

  • 127.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Versatile Functionalization of Polyester Hydrogels with Electroactive Aniline Oligomers2011In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 49, no 9, p. 2097-2105Article in journal (Refereed)
    Abstract [en]

    Functionalizing aliphatic polyester hydrogels with an aniline oligomer is a means of achieving electrically conductive and degradable hydrogels. To lower the aniline oligomer content while maintaining a high conductivity and to overcome the acidic degradation product from polylactide reported in our previous work, a series of electroactive and degradable hydrogels based on polycaprolactone (PCL) hydrogels and carboxyl-capped aniline pentamer (CCAP) were synthesized by a simple coupling reaction at room temperature. The reaction was carried out between the hydroxyl groups of hydroxyethylmethacrylate in a photopolymerized glycidyl methacrylate (GMA)-functionalized PCL-poly(ethylene glycol)-PCL degradable network and carboxyl group of CCAP, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as water-condensing agent and 4-dimethylamino-pyridine as catalyst. The electroactivity of the hydrogels was verified by cyclic voltammetry, which showed three pairs of redox peaks. The electrical conductivities and swelling ratios of these hydrogels were controlled by the CCAP content, the poly(ethylene glycol) molecular weight in the macromer, and the crosslinking density of the hydrogels.

  • 128.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sun, Yang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Mustafa, Kamal
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Electroactive porous tubular scaffolds with degradability and non-cytotoxicity for neural tissue regeneration2011In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 8, no 1, p. 144-153Article in journal (Refereed)
    Abstract [en]

    Electroactive degradable porous tubular scaffolds were fabricated from the blends of polycaprolactone and a hyperbranched degradable conducting copolymer at different feed ratios by a solution-casting/salt-leaching method. Scaning electron microscopy (SEM) and microcomputed tomography tests indicated that these scaffolds had homogeneously distributed interconnected pores on the cross-section and surface. The electrical conductivity of films with the same composition as the scaffolds was between 3.4×10(-6) and 3.1×10(-7)Scm(-1), depending on the ratio of hyperbranched degradable conducting copolymer to polycaprolactone. A hydrophilic surface with a contact angle of water about 30° was achieved by doping the films with (±)-10-camphorsulfonic acid. The mechanical properties of the films were investigated by tensile tests, and the morphology of the films was studied by SEM. The scaffolds were subjected to the WST test (a cell proliferation and cytotoxicity assay using water-soluble tetrazolium salts) with HaCaT keratinocyte cells, and the results show that these scaffolds are non-cytotoxic. These degradable electroactive tubular scaffolds are good candidates for neural tissue engineering application.

  • 129.
    Gustafsson, Emil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johansson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Direct Adhesive Measurements between Wood Biopolyrner Model Surfaces2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 10, p. 3046-3053Article in journal (Refereed)
    Abstract [en]

    For the first time the dry adhesion was measured for an all-wood biopolymer system using Johnson-Kendall-Roberts (JKR) contact mechanics. The polydimethylsiloxane hemisphere was successfully surface-modified with a Cellulose I model surface using layer-by-layer assembly of nanofibrillated cellulose and polyethyleneimine. Flat surfaces of cellulose were equally prepared on silicon dioxide substrates, and model surfaces of glucomannan and lignin were prepared on silicon dioxide using spin-coating. The measured work of adhesion on loading and the adhesion hysteresis was found to be very similar between cellulose and all three wood polymers, suggesting that the interaction between these biopolymers do not differ greatly. Surface energy calculations from contact angle measurements indicated similar dispersive surface energy components for the model surfaces. The dispersive component was dominating the surface energy for all surfaces. The JKR work of adhesion was lower than that calculated from contact angle measurements, which partially can be ascribed to surface roughness of the model surfaces and overestimation of the surface energies from contact angle determinations.

  • 130. Haider, Nadejzda
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    A rapid ultrasonic extraction technique to identify and quantify additives in poly(ethylene)1999In: Analyst (Cambridge, United Kingdom), Vol. 124, no 5, p. 797-800Article in journal (Refereed)
  • 131. Haider, Nadejzda
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Migration and release profile of Chimassorb 944 from low-density polyethylene film (LDPE) in simulated landfills1999In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, no 2, p. 321-328Article in journal (Refereed)
  • 132.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Migration of monomeric and polymeric PVC plasticizers2008In: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 211, p. 159-185Article, review/survey (Refereed)
    Abstract [en]

    This paper summarizes current literature on the migration of monomeric and polymeric PVC plasticizers from medical materials, food packaging, and toys. Especially highlighted is macromolecular engineering as a tool to increase the plasticizing efficiency and migration resistance for polymeric plasticizers. The effect of branching, molecular weight, end-group functionality, and polydispersity on plasticizer performance was evaluated by quantification of low-molecular-weight hydrolysis products, measurements of mechanical properties, weight loss, surface segregation, as well as the preservation of material properties during aging. A more migration-resistant polymeric plasticizer that also better preserved its material properties during aging was obtained by combining a low degree of branching, hydrolysis-protecting end-groups, and higher molecular weight.

  • 133.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Multiple headspace single-drop micro-extraction for quantitative determination of lactide in thermally-oxidized polylactide2010In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 95, no 3, p. 270-273Article in journal (Refereed)
    Abstract [en]

    Single-drop micro-extraction (SDME), an emerging micro-extraction technique, was combined with multiple headspace (MHS) extraction to allow quantitative determination of lactide in thermally-oxidized polylactide Different solvents, drop sizes and extraction times were tested to obtain best extraction efficiency and the method was further developed to obtain a linear regression plot for the Multiple extractions. The combination of SDME and MHS extraction offered several advantages over traditional liquid-solid and headspace extraction techniques No concentration step was needed and loss of volatiles was prevented as the ageing and extraction were performed in a closed system Matrix effects, that disturb the quantitation of analytes in solid samples, were removed by the multiple headspace extraction.

  • 134.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Kalrsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Weight losses and molecular weight changes correlated with the evolution of hydroxyacids in simulated in vivo degradation of homo-and copolymers of PLA and PGA1996In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 52, p. 283-291Article in journal (Refereed)
  • 135.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Solid phase microextraction (SPME) as an effective means to isolate degradation products in polymers1997In: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 5, p. 67-73Article in journal (Refereed)
    Abstract [en]

    A new sample preparation technique, solid phase microextraction (SPME), was compared with direct headspace-GC-MS with respect to the type and amount of identified compounds. Three types of LDPE films containing photosensitising additives according to the Scott-Gilead patents and pure LDPE were used as model substances. The polyethylene films were thermally aged at 80 degrees C after the induction period was surpassed by subjecting the materials to 100 h of UV radiation. The new SPME method was developed using nonpolar poly(dimethylsiloxane) and polar carbowax fibers to extract the low molecular weight products formed in the polyethylene films during aging. Many more products were identified after SPME followed by CC-MS than after direct headspace-GC-MS of the samples. The SPME method allowed the identification of homologous series of carboxylic acids, ketones, and furanones, while direct headspace-GC-MS identified only a few carboxylic acids (C1-C6) and small amounts of some ketones and furanones. In general, SPME was more effective in extracting less volatile products, and in particular, the polar carbowax fiber identified also C7-C12 carboxylic acids and 4-oxopentanoic acid. By SEC and FTIR we confirmed that the number and amount of former degradation products correlated well with the decrease in molecular weights and the amount of formed carbonyl compounds.

  • 136.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Solid-phase extraction and subsequent gas-chromatography-mass spectrometry analysis for identification of complex mixtures of degradation products in starch-based polymers1996In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 741, p. 251-263Article in journal (Refereed)
  • 137.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Susceptibility of starch-filled and starch-based LDPE to oxygen in water and air1997In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 66, p. 959-967Article in journal (Refereed)
  • 138. Hakkarainen, Minna
    et al.
    Albertsson, Ann-Christine
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Weight losses and molecular weight changes correlated with the evolution of hydroxy acids in simulated in vivo degradation of homo- and copolymers of PLA and PGA1996In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 52, no 3, p. 283-291Article in journal (Refereed)
  • 139.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Burman, Lina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Chromatographic Analysis and Total Luminescence Intensity as Tools for Early Degradation Detection and Degradation State Estimation2006In: ACS Symposium Series: Degradable Polymers and Materials, Principles and Practice / [ed] Kishan Khemani and Carmen Scholz, American Chemical Society (ACS), 2006, 1, p. 307-319Chapter in book (Refereed)
    Abstract [en]

    Indicator product concept, chromatographic fingerprinting in combination with multivariate data analysis and total luminescence intensity (TLI) are presented as tools for product evaluation, quality control and testing of degradable polymers. A correlation was shown between the number of chain scission and the release of dicarboxylic acids during photo-and thermo-oxidation of polyethylene. This opens for degradation state prediction from the amount of indicator products released. Multivariate data analysis of chromatographic fingerprints of dicarboxylic acids allowed classification of polyethylene materials both with respect to the degradation state and pro-oxidant system. Total luminescence intensity proved to be an excellent tool for early degradation detection and classification of polyethylene materials. Further applications could include classification of materials with respect to durability or degradability, evaluation of antioxidant or pro-oxidant

  • 140.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Update on polylactide based materials2011 (ed. 1)Book (Other academic)
    Abstract [en]

    Today both scientists and industry are working to develop more environmentally friendly processes and materials. One of the most current topics is the development of energy and materials from renewable resources. There are fascinating developments in this area and advanced designed products can today be formed in an environmentally friendly way. Polylactide based materials are among the most promising synthetic renewable resource based materials. There is currently extensive research going on to develop polylactide based materials for different applications. These developments include both the use of new resources, development of more effective and environmentally friendly processes as well as modification and tailoring of material properties and degradability to broaden the application range.

    This book discusses recent developments in polylactide based materials including the whole spectra from different material modifications, applications and properties to new advanced synthesis procedures. When it comes to degradable materials, an important aspect is also the influence of different modifications on material properties, degradability and degradation products. The different chapters present new emerging processes and synthetic techniques as well as different material modifications obtained by copolymerization or blending with degradable or inert, natural or synthetic polymers. In addition advancements and developments in polylactide stereocomplexes, nanocomposites and biocomposites are presented. The book is of interest both from the basic and applied science point of view as it presents the latest trends and demonstrates the versatility and great potential of polylactide based materials. Hopefully the book can inspire the reader to further develop synthesis procedures or new ways to modify polylactide materials to broaden the properties to suit new applications.

  • 141.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Gallet, Guillaume
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Prediction by multivariate data analysis of long-term properties of glassfiber reinforced polyester composites1999In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, p. 91-99Article in journal (Refereed)
    Abstract [en]

    The prediction of long-term properties of polymers has been analysed by identifiction of low molecular weight compounds in glassfibre-reinforced polyester composites which were subjected to accelerated ageing at 40 and 60 degrees C and 80 %-RH for periods up to 6 years. Before the accelerated ageing the materials were stored for 20 years at ambient temperature. After different ageing times the low molecular weight products in the materials were identified with GC-MS and headspace-GC-MS. Several different alcohols, phthalates and other aromatic compounds were identified. Temperature had a large influence on the degradation of phthalates and the formation of alcohols. In the first step we used principal component analysis (PCA) and partial least square (PLS) to locate outliers and to identify the products that were not connected to degradation time or temperature. After that PCA and PLS were used to reveal if unsaturated polyesters have different degradation mechanisms at 40 and 60 degrees C by comparing the amounts and types of degradation products. The relative influence of each factor on the degradation rate was studied and groups were made among the degradation products to define which degradation products are correlated with ageing time and temperature. Finally the ageing time was predicted from the amounts of degradation products (in that case the amount of products are considered as X factors and the time of degradation as a Y response). PCA showed that it was not possible to find a pattern in the HS-GC-MS chromatograms, due to the different volatility of the compounds. The score plots revealed the existence of domains which depended on the degradation temperature. Some of the compounds (diethyl phthalate, 2-propenyl ester of bensoic acid and bensoic acid) could not be predicted by the models. These products are not related to the degradation of the material itself. At 60 degrees C, 80% RH in air, PLS models showed a good correlation between amount of identified products and degradation time and it was possible to estimate the degradation time directly from the quantity of the 13 identified degradation products.

  • 142.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Gas Chromatography in analysis of polymers and rubbers2000In: Encyclopedia of Analytical Chemistry / [ed] R.A. Meyers, John Wiley & Sons, 2000, p. 7608-7623Chapter in book (Refereed)
  • 143.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Khabbaz, Farideh
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Biodegradation of polyethylene followed by assimilation of degradation products2003In: Biopolymers: Volume 9: Miscellaneous Biopolymers and Biodegradation of synthetic Polymers / [ed] Alexander Steinbüchel, Wiley-VCH Verlagsgesellschaft, 2003, p. 369-394Chapter in book (Refereed)
  • 144. Hammarling, L.
    et al.
    Gustavsson, H.
    Svensson, K.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Oskarsson, A.
    Migration of epoxidizied soya bean oil from plasticized PVC gaskets into baby food1997In: Food Addities and ContaminantsArticle in journal (Refereed)
  • 145.
    Hassanzadeh, Salman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aminlashgari, Nina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Chemo-selective high yield microwave assisted reaction turns cellulose to green chemicals2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 112, p. 448-457Article in journal (Refereed)
    Abstract [en]

    Exceptionally high cellulose liquefaction yields, up to 87% as calculated from the amount of solid residue, were obtained under mild conditions by utilizing the synergistic effect of microwave radiation and acid catalysis. The effect of processing conditions on degradation products was fingerprinted by rapid laser desorption ionization-mass spectrometry (LDI-MS) method. The reaction was chemo-tunable, enabling production of glucose (Glc) or levulinic acid (LeA) at significantly high selectivity and yields, the relative molar yields being up to 50 and 69%, respectively. A turning point from pure depolymerization to glucose to further degradation to levulinic acid and formic acid was observed at approximately 50% liquefaction or above 140 degrees C. This was accompanied by the formation of small amounts of solid spherical carbonized residues. The reaction was monitored by multiple analytical techniques. The high yields were connected to the ability of the process to break the strong secondary interactions in cellulose. The developed method has great potential for future production of green platform chemicals.

  • 146.
    Hassanzadeh, Salman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aminlashgari, Nina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Microwave-Assisted Recycling of Waste Paper to Green Platform Chemicals and Carbon Nanospheres2015In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 3, no 1, p. 177-185Article in journal (Refereed)
    Abstract [en]

    Effective high-yield recycling of waste paper to well-defined future platform chemicals and carbon nanospheres was demonstrated. The developed process utilized the exceptional combined effect of microwave irradiation and dilute acid catalyst to hydrothermally degrade cellulose in waste paper. The process was evaluated for three different waste papers, brown and white paper tissues and white printing paper. Different pretreatment processes were investigated to further increase the cellulose liquefaction efficiency. By utilizing soda pretreatment, liquefaction efficiencies as high as 8896 were achieved. The obtained liquefaction products were fingerprinted by NMR and LDI-MS, while the solid residues were analyzed by XRD, SEM, TGA, and FTIR As industrial-scale microwave reactors are currently under development, the developed method displays significant potential for recycling waste paper to green platform chemicals at the industrial scale.

  • 147. Hassanzadeh, Salman
    et al.
    Feng, Zhaoxuan
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    A proof-of-concept for folate-conjugated and quercetin-anchored pluronic mixed micelles as molecularly modulated polymeric carriers for doxorubicin2015In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 74, p. 193-204Article in journal (Refereed)
    Abstract [en]

    Pluronic, F127 (PEG-PPO-PEG, Mn = 12,500 g/mol) and reverse pluronic, 10R5 (PPO-PEG-PPO, Mn = 2000 g/mol) were molecularly modulated to reach multifunctional mixed micelle systems aiming to overcome some of the inherent weaknesses of pluronic based drug delivery systems. Targeting function was introduced by covalent attachment of folic acid to F127 (F127-FA), while quercetin was anchored to 10R5 (P-Q). The successful syntheses were evidenced by H-1 NMR, FTIR, DSC and UV-Vis. The proof-of-concept for the mixed micelles prepared from the drug anchored pluronics was demonstrated through reduced CMCs, slower release rates and increased Doxorubicin (DOX) encapsulation capacity from similar to 19% to similar to 43%. Quercetin therefore boosted the interactions of DOX with the hydrophobic core of the micelles. This was further evidenced by colloidal probe AFM which demonstrated almost doubled adhesion forces between the DOX coated probe and the quercetin modified pluronic as compared to the plain pluronic. The pre-biological essay of the DOX-modulated mixed micelle demonstrates promising properties. In addition quercetin has previously been proposed as combinatory drug to DOX enhancing its therapeutic function and reducing the side effects to normal cells.

  • 148.
    Hassanzadeh, Salman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology. Chemistry Department, School of Science, University of Tehran, Iran .
    Khoee, Sepideh
    Beheshti, Abolghasem
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Release of quercetin from micellar nanoparticles with saturated and unsaturated core forming polyesters - A combined computational and experimental study2015In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 46, p. 417-426Article in journal (Refereed)
    Abstract [en]

    Computational and experimental studies were combined to obtain new insight into the widely reported anomalous release mechanism of hydrophobic drug (quercetin) from polymeric micellar nanopartides. Saturated and unsaturated amphiphilic triblock copolymers from monomethoxy polyethylene glycol (mPEG), poly(butylene adipate) (PBA) and poly(cis-2-butene adipate) (PCBA) (mPEG-PBA-mPEG and mPEG-PCBA-mPEG) were utilized as model polymers to specify the contribution of polymer-micelle degradation and polymer-drug interactions on the observed differences in the release rates by applicable computational investigation and experimental evaluations. Monitoring the size of the micelles through the releasing process together with hydrolytic degradation studies of the core forming polymers proved that the contribution of polymer hydrolysis and micelle degradation on the observed differences in the release rates during the release time window was minimal. The compatibility between quercetin and the core forming polymer is another factor influencing the drug encapsulation and the relative release rate and it was therefore investigated theoretically (using density functional theory (DFT) at B3LYP/6-311(++)G level of theory) and experimentally (FT-IR imaging). The drug-polymer interactions in the core were shown to be much more important than the polymer and/or micelle swelling-dissociation-degradation processes under the studied conditions.

  • 149. He, M.
    et al.
    Jiang, H.
    Wang, R.
    Xie, Y.
    Zhao, Weifeng
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology. Sichuan Univ, Peoples R China.
    Zhao, C.
    A versatile approach towards multi-functional surfaces via covalently attaching hydrogel thin layers2016In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 484, p. 60-69Article in journal (Refereed)
    Abstract [en]

    In this study, a robust and straightforward method to covalently attach multi-functional hydrogel thin layers onto substrates was provided. In our strategy, double bonds were firstly introduced onto substrates to provide anchoring points for hydrogel layers, and then hydrogel thin layers were prepared via surface cross-linking copolymerization of the immobilized double bonds with functional monomers. Sulfobetaine methacrylate (SBMA), sodium allysulfonate (SAS), and methyl acryloyloxygen ethyl trimethyl ammonium chloride (METAC) were selected as functional monomers to form hydrogel layers onto polyether sulfone (PES) membrane surfaces, respectively. The thickness of the formed hydrogel layers could be controlled, and the layers showed excellent long-term stability. The PSBMA hydrogel layer exhibited superior antifouling property demonstrated by undetectable protein adsorption and excellent bacteria resistant property; after attaching PSAS hydrogel layer, the membrane showed incoagulable surface property when contacting with blood confirmed by the activated partial thromboplastin time (APTT) value exceeding 600 s; while, the PMETAC hydrogel thin layer could effectively kill attached bacteria. The proposed method provides a new platform to directly modify material surfaces with desired properties, and thus has great potential to be widely used in designing materials for blood purification, drug delivery, wound dressing, and intelligent biosensors.

  • 150. He, Min
    et al.
    Cui, Xiaofei
    Jiang, Huiyi
    Huang, Xuelian
    Zhao, Weifeng
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Zhao, Changsheng
    Super-Anticoagulant Heparin-Mimicking Hydrogel Thin Film Attached Substrate Surfaces to Improve Hemocompatibility2017In: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 17, no 2Article in journal (Refereed)
    Abstract [en]

    In this study, heparin-mimicking hydrogel thin films are covalently attached onto poly(ether sulfone) membrane surfaces to improve anticoagulant property. The hydrogel films display honeycomb-like porous structure with well controlled thickness and show long-term stability. After immobilizing the hydrogel films, the membranes show excellent anticoagulant property confirmed by the activated partial thromboplastin time values exceeding 600 s. Meanwhile, the thrombin time values increase from 20 to 61 s as the sodium allysulfonate proportions increase from 0 to 80 mol%. In vitro investigations of protein adsorption and blood-related complement activation also confirm that the membranes exhibit super-anticoagulant property. Furthermore, gentamycin sulfate is loaded into the hydrogel films, and the released drug shows significant inhibition toward E. coli bacteria. It is believed that the surface attached heparin-mimicking hydrogel thin films may show high potential for the applications in various biological fields, such as blood contacting materials and drug loading materials.

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