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Controlled synthesis of star-shaped L-lactide polymers using new spirocyclic tin initiators
KTH, Superseded Departments, Polymer Technology.ORCID iD: 0000-0002-1922-128X
KTH, Superseded Departments, Polymer Technology.
2002 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 3, no 4, 684-690 p.Article in journal (Refereed) Published
Abstract [en]

The reaction between pentaerythritol ethoxylate compounds and dibutyltin oxide was developed as a route to synthesize two new spirocyclic tin initiators. The initiators were successfully synthesized and they were characterized by H-1 NMR and differential scanning calorimetry (DSC). The H-1 NMR spectra showed the characteristic signals for the methylene protons in the ether chains. Furthermore, the usefulness of the new initiators was examined in ring-opening polymerizations of L-lactide in chloroform at 60 degreesC. L-Lactide was polymerized at monomer-to-initiator ([M]/[I]) ratios between 20 and 500. The results indicated that the initiation was instantaneous and that the molecular weight distribution was very narrow, <1.13, The number average molecular weight could be controlled by the [M]/[I] ratio, and the yield was very high. H-1 NMR, size exclusion chromatography, and DSC were used to clarify the architecture, The expected results were obtained. The star-shaped polymers had a smaller hydrodynamic volume, and the melting point was lower than that obtained for the corresponding linear poly(L-lactide).

Place, publisher, year, edition, pages
2002. Vol. 3, no 4, 684-690 p.
Keyword [en]
LIVING CATIONIC-POLYMERIZATION, RING-OPENING POLYMERIZATION, BLOCK-COPOLYMERS, STANNOUS OCTOATE, POLYLACTONES, PENTAERYTHRITOL, POLYSTYRENE, POLY(L-LACTIDE), MECHANISM, ALKOXIDES
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-13188DOI: 10.1021/bm020009oISI: 000176716700008OAI: oai:DiVA.org:kth-13188DiVA: diva2:321695
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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