| 1. |
- Berglund, Per, et al.
(författare)
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Switched enantiopreference of Humicola lipase for 2-phenoxyalkanoic acid ester homologs can be rationalized by different substrate binding modes
- 1999
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Ingår i: Tetrahedron. - 0957-4166 .- 1362-511X. ; 10:21, s. 4191-4202
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Tidskriftsartikel (refereegranskat)abstract
- Humicola lanuginosa lipase was used for enantioselective hydrolyses of a series of homologous 2-phenoxyalkanoic acid ethyl esters. The enantioselectivity (E-value) of the enzyme changed from an (R)-enantiomer preference for the smallest substrate, 2-phenoxypropanoic acid ester, to an (S)-enantiomer preference for the homologous esters with longer acyl moieties. The E-values span the range from E=13 (R) to E=56 (S). A molecular modeling study identified two different substrate-binding modes for each enantiomer. We found that the enantiomers favored different modes. This discovery provided a model that offered a rational explanation for the observed switch in enantioselectivity. (C) 1999 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Brännström, Sara, et al.
(författare)
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Itaconate based polyesters : Selectivity and performance of esterification catalysts
- 2018
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 103, s. 370-377
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Tidskriftsartikel (refereegranskat)abstract
- The performance of different esterification catalysts was studied for the use in synthesis of renewable polyesters from dimethyl itaconate (DMI), dimethyl succinate (DMS) and 1,4-butanediol (BD). Itaconic acid and derivatives such as DMI are interesting monomers because of their multiple functionalities and previous work has shown great potential. However, the multiple functionalities also pose challenges to avoid side reactions such as thermally initiated, premature, radical crosslinking and/or isomerization of the 1,1-disubstituted unsaturation. Additionally, the two carboxylic acids have inherently different reactivity. One key factor to control reactions with IA is to understand the performance of different catalysts. In this study, six esterification catalysts were investigated; immobilized Candida antarctica lipase B (CalB), titanium(IV)butoxide (Ti(OBu)4), p-toluenesulfonic acid (pTSA), sulfuric acid (H2SO4), 1,8-diazabicycloundec-7-ene (DBU), and 1,5,7-triazabicyclodec-5-ene (TBD). CalB and Ti(OBu)4 were selected for further characterization with appreciable differences in catalytic activity and selectivity towards DMI. CalB was the most effective catalysts and was applied at 60 °C while Ti(OBu)4 required 160 °C for a reasonable reaction rate. CalB was selective towards DMS and the non-conjugated side of DMI, resulting in polyesters with itaconate-residues mainly located at the chain ends, while Ti(OBu)4 showed low selectivity, resulting in polyesters with more randomly incorporated itaconate units. Thermal analysis of the polyesters showed that the CalB-catalyzed polyesters were semi-crystalline, whereas the Ti(OBu)4-catalyzed polyesters were amorphous, affirming the difference in monomer sequence. The polyester resins were crosslinked by UV-initiated free radical polymerization and the material properties were evaluated and showed that the crosslinked materials had similar material properties. The films from the polyester resins catalyzed by CalB were furthermore completely free from discoloration whereas the film made from the polyester resins catalyzed with Ti(OBu)4 had a yellow color, caused by the catalyst. Thus, it has been shown that CalB can be used to attain sustainable unsaturated polyesters resins for coating applications, exhibiting equally good properties as resins obtained from traditional metal-catalysis.
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| 3. |
- Brännström, Sara, et al.
(författare)
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Tailoring Thermo-Mechanical Properties of Cationically UV-Cured Systems by a Rational Design of Vinyl Ether Ester Oligomers using Enzyme Catalysis
- 2018
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Ingår i: Macromolecular Chemistry and Physics. - : WILEY-V C H VERLAG GMBH. - 1022-1352 .- 1521-3935. ; 219:21
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Tidskriftsartikel (refereegranskat)abstract
- There is a demand for new sustainable polymeric materials. Vinyl ethers are, in this context, attractive oligomers since they polymerize fast, are non-toxic, and can be polymerized under ambient conditions. The availability of vinyl ether oligomers is, however, currently limited due to difficulties in synthesizing them without using tedious synthesis routes. This work presents the synthesis of a series of vinyl ether ester oligomers using enzyme catalysis under solvent-free conditions and the subsequent photoinduced cationic polymerization to form polymer thermosets with T(g)s ranging from -10 to 100 degrees C. The whole process is very efficient as the synthesis takes less than 1 h with no need for purification and the crosslinking is complete within 2 min.
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| 4. |
- Eriksson, Magnus, et al.
(författare)
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Enzymatic One-Pot Route to Telechelic Polypentadecalactone Epoxide : Synthesis, UV Curing, and Characterization
- 2009
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:11, s. 3108-3113
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Tidskriftsartikel (refereegranskat)abstract
- In an enzymatic one-pot procedure immobilized lipase B from Candida antarctica was used to synthesize semicrystalline diepoxy functional macromonomers based on glycidol, pentadecalactone, and adipic acid. By changing the stoichiometry of the building blocks. macromonomers of controlled molecular weight front 1400 to 2700 g mol(-1) could be afforded. The enzyme-catalyzed reaction went to completion (conversion >= 95%) within 24 h at 60 degrees C. After removal of the enzyme, the produced macromonomers were used for photopolymerization without any purification. The macromonomers readily copolymerized cationically with a cycloaliphatic diepoxide (Cyracure UVR-6110; CA-dE) to high conversion. The cross-linked copolymers formed a durable film with a degree of crystallinity depending on the macromonomer size and amount of CA-dE used, without CA-dE the macromonomers homopolymerized only to a low degree. Combined with CA-dE conversions of 85-90% were determined by FT-Raman spectroscopy. The films became more durable once reinforced with CA-dE, increasing the cross-link density and reducing the crystallinity of the PDL segments in the films.
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| 5. |
- Eriksson, Magnus G., et al.
(författare)
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One-pot enzymatic polycondensation to telechelic methacrylate-functional oligoesters used for film formation
- 2011
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Ingår i: POLYM CHEM. - Cambridge : ROYAL SOC CHEMISTRY. - 1759-9954 .- 1759-9962. ; 2:3, s. 714-719
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Tidskriftsartikel (refereegranskat)abstract
- Based on largely renewable monomers, an enzymatic one-pot polycondensation route towards functional oligomers with targeted molecular weights and end-groups was developed. This one-pot synthesis was performed by combining Candida antarctica lipase B (CALB), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol, and divinyl adipate under reduced pressure (72 mbar) at 60 degrees C. The polymerization went to completion (>95% conversion for all monomers) within 24 h and the fraction of methacrylate end-groups was >90%. Three targeted dimethacrylate functional oligomers with molecular weights of 920, 1700 and 2500 g mol(-1) (degrees of polymerization 4, 8, and 13 respectively) were synthesized. The oligomer products were characterized by NMR, MALDI-TOF MS and SEC. The dimethacrylate functional oligomers were further UV homopolymerized or combined with a tetrathiol crosslinker to demonstrate the potential to produce novel networks with tunable thermal properties dependent on chain length of the telechelic building blocks. This research is the first to demonstrate methacrylate functionalization and condensation polymerization in a one step process, which expands the growing toolbox for polymer/material chemists towards an increased throughput in available macromonomers used in material design.
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| 6. |
- Eriksson, Magnus, et al.
(författare)
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One-Pot Enzymatic Route to Tetraallyl Ether Functional Oligoesters : Synthesis, UV Curing, and Characterization
- 2010
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Ingår i: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 48:23, s. 5289-5297
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Tidskriftsartikel (refereegranskat)abstract
- An enzymatic one-pot route in bulk was used to synthesize tetraallyl ether (tAE) functional oligomers based on divinyl adipate, 1,4-butanediol and trimethylolpropane diallyl ether. By using lipase B from Candida antarctica as catalyst and varying the stoichiometric ratio of monomers, it was possible to reach targeted molecular weights (from 1300 to 3300 g mol(-1)) of allyl-ether functional polyesters. The enzyme catalyzed reaction reached completion (>98% conversion based on all monomers) within 24 h at 60 degrees C, under reduced pressure (72 mbar) resulting in similar to 90% yield after filtration. The tAE-functional oligoesters were photopolymerized, without any purification other than removal of the enzyme by filtration, with thiol functional monomers (dithiol, tetrathiol) in a 1: 1 ratio thiol-ene reaction. The photo-initiator, 2,2-dimethoxy-2-phenylacetophenone, was used to improve the rate of reaction under UV light. High conversions (96-99% within detection limits) were found for all thiol-ene films as determined by FT-Raman spectroscopy. The tAE-functional oligoesters were characterized by NMR, MALDI, and SEC. The UV-cured homopolymerized films and the thiol-ene films properties were characterized utilizing DSC and DMTA.
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| 7. |
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| 8. |
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| 9. |
- Finnveden, Maja, 1986-, et al.
(författare)
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Lipase-Catalyzed Synthesis of Renewable Plant Oil-Based Polyamides.
- 2019
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Finnveden, Maja, 1986-, et al.
(författare)
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Lipase Catalyzed Synthesis of renewable plant oil-based polyamides
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Enzyme catalyzed synthesis towards 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 catalyst. The results from the two catalysts were comparable. However, the amount of lipase added was 1200 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-diaminododecan to synthesize oligoamides of two different lengths.
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