| 1. |
- Lindblad, M. S., et al.
(författare)
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Biodegradable polymers from renewable sources : Rheological characterization of hemicellulose-based hydrogels
- 2005
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 6:2, s. 684-690
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Tidskriftsartikel (refereegranskat)abstract
- Hemicellulose-based hydrogels were prepared by radical polymerization of 2-hydroxyethyl methacrylate or poly(ethylene glycol) dimethacrylate with oligomeric hydrosoluble hemicellulose modified with well-defined amounts of methacrylic functions. The polymerization reaction was carried out in water at 40 degrees C using a redox initiator system. The hydrogels were in general elastic, soft, and easily swellable in water. Their viscoelastic properties were determined by oscillatory shear measurements on 2 mm thick hydrogels under a slight compression to avoid slip, over the frequency range 10(-1) to 10(2). The rheological characterization indicated that the elastic response of the hydrogels was stronger than the viscous response, leading to the conclusion that the hydrogel systems displayed a predominantly solidlike behavior. The curves showed an increase in shear storage modulus with increasing cross-linking density. The nature of the synthetic comonomer in the hemicellulose-based hydrogels also influenced the shear storage modulus. Comparison of hemicellulose-based hydrogels with pure poly(2-hydroxyethyl methacrylate) hydrogels showed that their behaviors were rather similar, demonstrating that the synthetic procedure made it possible to prepare hemicellulose-based hydrogels with properties similar to those of pure poly(2-hydroxyethyl methacrylate) hydrogels.
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| 2. |
- Ranucci, E., et al.
(författare)
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New ester and lactone end-functionalized N-vinyl-2-pyrrolidinone oligomers
- 2000
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Ingår i: Macromolecular Chemistry and Physics. - 1022-1352 .- 1521-3935. ; 201:12, s. 1219-1225
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Tidskriftsartikel (refereegranskat)abstract
- New oligomers of N-vinyl-2-pyrrolidinone functionalized at one end with either ester or lactone functions were obtained by radical polymerization in the presence of different ester (methyl isobutyrate and methyl phenylacetate) and lactone (epsilon-caprolactone, delta-valerolactone and gamma-btyrolactone) compounds as chain transfer agents. The oligomeric samples obtained were characterized in terms of molecular weight and molecular weight distribution by means of analytical size exclusion chromatography (SEC), using purposely synthesized poly(N-vinyl-2-pyrrolidinone) standards. The chain transfer constant C-tau of either methyl isobutyrate, delta-valerolactone, or gamma-butyrolactone towards N-vinyl-2-pyrrolidinone were determined with the help of the known cumulative number-average degree of polymerization (X) over bar(n) and monomer conversion Y-t of the samples during the reaction.
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| 3. |
- Lindblad, M. S., et al.
(författare)
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Biodegradable polymers from renewable sources. New hemicellulose-based hydrogels
- 2001
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Ingår i: Macromolecular rapid communications. - 1022-1336 .- 1521-3927. ; 22:12, s. 962-967
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Tidskriftsartikel (refereegranskat)abstract
- Communication: Hemicellulose/poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogels were prepared by the radical polymerization of HEMA with hemicellulose purposely modified with well-defined amounts of methacrylic functions using a redox initiator system. Oligomeric hydrosolube hemicelluloses produced from spruce chips were used for modification studies. The chemical modification of hemicellulose was performed with 2-[(1-imidazolyl)formyloxy]ethyl methacrylate as a modifying agent and triethylamine as the catalyst. The kinetics of the modification reaction was monitored by means of H-1 NMR spectroscopy. The resulting hydrogels obtained after a 30 min reaction were homogeneous, elastic, and transparent materials.
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| 4. |
- Lindblad, M. S., et al.
(författare)
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Polymers from renewable resources
- 2002
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Ingår i: Advances in Polymer Science. - 0065-3195 .- 1436-5030. ; 157, s. 139-161
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Forskningsöversikt (refereegranskat)abstract
- From the point of view of making novel polymers with inherent environment-favorable properties such as renewability and degradability, a series of interesting monomers are found in the metabolisms and cycles of nature. This review presents and discusses a number of aliphatic polyesters which show interesting applications as biomedical materials and degradable packages. Available from nature are amino acids, microbial metabolites from the conversion of glucose and other monosaccharides (e.g., acetic acid, acetone, 2,3-butanediol, butyric acid, isopropanol, propionic acid), lactic acid, ethanol and fatty acids. A series of biodegradable polymers with different properties and different potential industrial uses were made starting with succinic acid and/or 1,3-propanediol. There were two routes for making the polyester-based materials; the direct ring-opening polymerization of lactones (cyclic esters) synthesized from 1,3-propanediol, and the chain-extension of alpha,omega-dihydroxy-terminated oligomeric polyesters produced by thermal polycondensation of 1,3-propanediol and succinic acid (oligo(propylene succinate)s).
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| 5. |
- Liu, Y., et al.
(författare)
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New biodegradable polymers from renewable sources : Polyester-carbonates based on 1,3-Propylene-co-1,4-cyclohexanedimethylene succinate
- 2001
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Ingår i: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 39:14, s. 2508-2519
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Tidskriftsartikel (refereegranskat)abstract
- alpha,omega -Dihydroxy-terminated copolymeric oligomers of a 1,3-propylene/1,4-cyclohexanedimethylene succinate structure were obtained by the thermal polycondensation of 1,3-propanediol/1,4-cyclohexanedimethanol/s acid mixtures. They were subsequently chain-extended via phosgene synthesis to high molecular weight aliphatic/alicyclic copolyester-carbonates. These new polymers, besides having a biodegradable backbone, originate from two monomers, namely, 1,3-propanediol and succinic acid, which can be obtained by renewable sources. Therefore, they have a potential as environmentally friendly materials. All synthesized materials were characterized in reference to their molecular structure by H-1 NMR and C-13 NMR. Their molecular weights and molecular weight distributions were determined by size exclusion chromatography, and their main thermal properties were measured by DSC. Spectroscopic characterizations were in full agreement with the proposed structures. 1,4-Cyclohexanedimethanol was used as a diol comonomer to improve the overall thermal properties of poly(1,3-propylene succinate). The results of the characterization performed show that the initial expectations were only partially satisfied.
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| 6. |
- Liu, Y., et al.
(författare)
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New biodegradable polymers from renewable sources - Segmented copolyesters of poly(1,3-propanediol succinate) and poly(ethylene glycol)
- 2002
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Ingår i: Journal of bioactive and compatible polymers (Print). - : SAGE Publications. - 0883-9115 .- 1530-8030. ; 17:3, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- New high-molecular-weight hydrophobic/hydrophilic segmented copolymers of poly(ester-ether-carbonate) structure, containing poly(1,3-propylene succinate) (SP) and poly(ethylene glycol) (PEG) segments in the main chain, were synthesized and characterized. These copolymers were obtained by a two-step chain-extension reaction performed by the thermal polycondensation of alpha,omega-dihydroxy-oligo(1,3-propylene succinate) with PEG1000 and PEG2000, respectively. The molecular structure of all the synthesized materials was characterized by H-1-NMR, by SEC for molecular weights, and by DSC for thermal properties. The molecular characterizations were in agreement with the proposed structures. Solubility and swellability tests indicated that the introduction of hydrophilic PEG segments into the high molecular weight poly(1,3-propylene succinate)s imparted amphiphilic character to the new materials. This is expected to influence the biocompatibility and biodegradability of these materials. The new polymers, besides having a degradable backbone, were derived from the monomers, 1,3-propanediol and succinic acid, which are both obtainable from renewable sources. Therefore, they have a potential as environmental friendly materials.
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| 7. |
- Liu, Y., et al.
(författare)
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New segmented poly(ester-urethane)s from renewable resources
- 2001
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Ingår i: Journal of Polymer Science Part A. - 0887-624X .- 1099-0518. ; 39:5, s. 630-639
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Tidskriftsartikel (refereegranskat)abstract
- The physical and mechanical properties of aliphatic homopolyesters from monomers obtainable from renewable resources, namely, 1,3-propanediol and succinic acid, were improved by their combination with aromatic urethane segments capable of establishing strong intermolecular hydrogen bonds. Segmented poly(ester-urethane)s were synthesized from dihydroxy-terminated oligo(propylene succinate)s chain-extended with 4,4'-diisophenylmethane diisocyanate. The newly synthesized materials were exhaustively characterized by H-1 NMR spectroscopy, size exclusion chromatography, differential scanning calorimetry, dynamic mechanical analysis, and with respect to their main static mechanical properties, an Instron apparatus was used. The average repeat number of the hard segments, evaluated by NMR, ranged from 4 to 9, whereas that of the flexible segments was about 14. The degree of crystallinity, glass-transition temperature, melting point, tensile strength, elongation, and Young's modulus were influenced by the ratio between hard and soft segments of the segmented copolymer in a predictable way. The results demonstrated that poly(ester-urethane)s from 1,3-propanediol and succinic acid are promising thermoplastics.
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| 8. |
- Ranucci, E., et al.
(författare)
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New biodegradable polymers from renewable sources. High molecular weight poly(ester carbonate)s from succinic acid and 1,3-propanediol
- 2000
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Ingår i: Macromolecular rapid communications. - 1022-1336 .- 1521-3927. ; 21:10, s. 680-684
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Tidskriftsartikel (refereegranskat)abstract
- High molecular weight poly(ester carbonate)s have been prepared by a two-step chain-extension reaction performed on oligomeric alpha,omega-dihydroxy-terminated poly(1,3-propylene succinate) in turn obtained by thermal polycondensation of excess 1,3-propanediol with succinic acid. The new polymers have a biodegradable backbone and derive from renewable sources. Therefore, they have a potential as environment-friendly materials.
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