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Synthesis of End-functionalized Polyesters byRing-Opening Polymerization of ε-Caprolactone
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
2004 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The main objective of this work was to investigate the ring-opening polymerizations

of cyclic esters by enzyme catalysis and cationic activated monomer polymerization

in the search for new polymer materials and fiber-based composites. Candida

antarcica lipase B was used for end-functionalization of poly(ε-caprolactone) and in

the copolymerization of D,L-lactide and ε-caprolactone. The reactions were

characterized with regard to polymer structure and molecular weight distributions by

NMR, MALDI-TOF MS and GPC.

The copolymerization of D,L-lactide and ε-caprolactone initially leads to a

nonrandom incorporation of lactide. D,L-Lactide is incorporated as the dimer in the

initial stage, when ε-caprolactone is practically excluded from the reaction. During

this stage, the polymerization is slowed by the presence of D,L-lactide as compared to

a neat ε-caprolactone polymerization. After the initial stage, ε-caprolactone and

lactide are polymerized at approximately equal rates.

In cationic activated monomer polymerizations of ε-caprolactone, lactic acid can act

as initiator, catalyst and terminator. Molecular weights distributions and reaction

times are comparable with the corresponding lipase-catalyzed reactions. If more

nucleophilic initiators, e.g. methyl β-D-glucopyranoside, sucrose or raffinose, are

present in the reaction mixture, lactic acid catalyzes the reaction without participating

in the initiation. The regioselectivity of the acylation is well agreement with the

corresponding lipase catalyzed reaction.

Both methods have several advantages: the catalysts can be handled without need

for extraordinary precautions with regard to atmosphere, humidity or equipment. The

polymerizations are performed under mild reaction conditions, with non-toxic

catalysts that can be recycled, and show the possibility of controlling end-group

functionalization with high precision.

Place, publisher, year, edition, pages
Mid Sweden Univ , 2004. , p. 36
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 8
National Category
Other Basic Medicine
Identifiers
URN: urn:nbn:se:miun:diva-9342OAI: oai:DiVA.org:miun-9342DiVA, id: diva2:227281
Presentation
(English)
Available from: 2009-07-10 Created: 2009-07-10 Last updated: 2018-01-13Bibliographically approved
List of papers
1. Structural Characterization of a Lipase-Catalyzed Copolymerization of epsilon-Caprolactone and D,L-Lactide
Open this publication in new window or tab >>Structural Characterization of a Lipase-Catalyzed Copolymerization of epsilon-Caprolactone and D,L-Lactide
Show others...
2003 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 4, no 4, p. 1068-1071Article in journal (Refereed) Published
Abstract [en]

The copolymerization of epsilon-caprolactone (epsilon-CL) and D,L-lactide catalyzed by Candida antarctica lipase B was studied. Copolymerizations with different epsilon-CL-to-lactide ratios were carried out, and the product was monitored and characterized by MALDI-TOF MS, GPC, and H-1 NMR. The polymerization of epsilon-CL, which is normally promoted by C. antarctica lipase B, is initially slowed by the presence of lactide. During this stage, lactide is consumed more rapidly than epsilon-CL, and the incorporation occurs dimer-wise with regard to the lactic acid (LA) units. As the reaction proceeds, the relative amount of CL units in the copolymer increases. The nonrandom copolymer structure disappears with time, probably due to a lipase-catalyzed transesterification reaction. In the copolymerizations with a low content of lactide, macrocycles of poly(epsilon-caprolactone) and copolymers having up to two LA units in the ring were detected.

Keywords
copolymerization, caprolactone, lactide
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-1627 (URN)10.1021/bm0340725 (DOI)000184360400029 ()12857093 (PubMedID)0042698334 (Scopus ID)435 (Local ID)435 (Archive number)435 (OAI)
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2017-12-13Bibliographically approved
2. Selective organocatalytic ring-opening polymerization: A versatile route to carbohydrate-functionalized poly(e-caprolactenes)
Open this publication in new window or tab >>Selective organocatalytic ring-opening polymerization: A versatile route to carbohydrate-functionalized poly(e-caprolactenes)
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2004 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 16, p. 5889-5893Article in journal (Refereed) Published
Abstract [en]

Cationic catalysis using simple carboxylic acids to combine the ring-opening polymerization of c-caprolactone and the regioselective acylation of carbohydrates has been investigated. L-Lactic acid catalyzed the acylation of methyl beta-D-glucopyranoside and sucrose with epsilon-caprolactone in high yield by bulk polymerization at 120 degreesC. The main products were regioselectively acylated on the primary hydroxyl groups of the carbohydrate end groups. The overall conversion to methyl beta-D-glucopyranoside-functionalized poly(epsilon-caprolactone) was more than 90%, M-w 2000 and polydispersity index 1.5, with one major product methyl 6-O-poly(epsilon-caprolactone)-beta-D-glucopyranoside, in agreement with the corresponding Candida antarctica lipase B-catalyzed acylation

Keywords
organocatalysis, carbohydrate, polyesters
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:miun:diva-1110 (URN)10.1021/ma049562j (DOI)000223160000013 ()2-s2.0-4344700611 (Scopus ID)2055 (Local ID)2055 (Archive number)2055 (OAI)
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2018-01-13Bibliographically approved

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