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Use of germanium initiators in ring-opening polymerization of L-lactide
KTH, Superseded Departments, Polymer Technology.ORCID iD: 0000-0002-1922-128X
KTH, Superseded Departments, Polymer Technology.
2003 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 41, no 19, 3074-3082 p.Article in journal (Refereed) Published
Abstract [en]

Three different, new germanium initiators were used for ring-opening polymerization Of L-lactide. Chlorobenzene and 120 degreesC was a usable polymerization system for solution polymerization, and the results from the polymerizations depended on the initiator structure and bulkiness around the insertion site. The average molecular weights as measured by size exclusion chromatography increased linearly with the monomer conversion, and the molecular weight dispersity was around 1.2 for initiators 1 and 2, whereas it was around 1.4 for initiator 3. The average molecular weight of poly(L-lactide) could be controlled with all three initiators by adding different ratios of monomer and initiator. The reaction rate for the solution polymerization was, however, overall extremely slow. With an initial monomer concentration of 1 M and a monomer-to-initiator ratio of 50, the conversion was 93% after 161 h for the fastest initiator. In bulk polymerization, 160 degreesC, the conversion was 90% after 10 h.

Place, publisher, year, edition, pages
2003. Vol. 41, no 19, 3074-3082 p.
Keyword [en]
germanium initiators, ring-opening polymerization, aliphatic polyesters, block copolymers, EPSILON-CAPROLACTONE, ALUMINUM ALKOXIDES, POLYLACTONES, 1, 5-DIOXEPAN-2-ONE, SALTS, LACTONES, LACTATE
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-13185DOI: 10.1002/pola.10887ISI: 000185172500016OAI: oai:DiVA.org:kth-13185DiVA: diva2:321689
Note
QC 20100602Available from: 2010-06-02 Created: 2010-06-02 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Novel Possibilities for Advanced Molecular Structure Design for Polymers and Networks
Open this publication in new window or tab >>Novel Possibilities for Advanced Molecular Structure Design for Polymers and Networks
2003 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Synthetic and degradable polymers are an attractive choicein many areas, since it is possible to control the way in whichthey are manufactured; more specifically, pathways tomanipulate the architecture, the mechanical properties and thedegradation times have been identified. In this work,L-lactide, 1,5-dioxepan-2-one and ε-caprolactone were usedas monomers to synthesize polymers with different architecturesby ring-opening polymerization. By using novel initiators,triblock copolymers, functionalized linear macromonomers andstar-shaped aliphatic polyesters with well-defined structureshave been synthesized. To synthesize triblock copolymers,cyclic germanium initiators were studied. The polymerizationproceeded in a controlled manner although the reaction rateswere low. To introduce functionality into the polymer backbone,functionalized cyclic tin alkoxides were prepared and used asinitiators. During the insertion-coordination polymerization,the initiator fragment consisting mainly of a double bond wasincorporated into the polymer backbone. The double bond wasalso successfully epoxidized and this gave unique possibilitiesof synthesizing graft polymers with precise spacing. Themacromonomer technique is a very effective method for producingwell-defined graft polymers. Spirocyclic tin initiators weresynthesized and used to construct star-shaped polymers. Thestar-shaped polymers were subsequently crosslinked in apolycondensation reaction. These crosslinked structures swelledin water, and swelling tests showed that by changing thestructure of the hydrogel network, the degree of swelling canbe altered. A first evaluation of the surface characteristicsof the linear triblock copolymers was also performed. AFManalysis of the heat-treated surfaces revealed nanometer-scalefibers and tests showed that keratinocytes were able to growand proliferate on these surfaces.

Place, publisher, year, edition, pages
Stockholm: KTH, 2003. 78 p.
Keyword
ring-opening polymerization, coordination-insertion, germanium, cyclic tin alkoxides, spirocyclic initiators, poly(L-lactide), poly(1, 5-dioxepan-2-one), triblock, star-shaped, network, functionalization, morphology, AFM
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-3623 (URN)91-7283-577-X (ISBN)
Public defence
2003-10-31, 00:00 (English)
Note
QC 20100602Available from: 2003-10-28 Created: 2003-10-28 Last updated: 2010-06-02Bibliographically approved

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