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Fibrillar structure of resorbable microblock copolymers based on 1,5-dioxepan-2-one and epsilon-caprolactone
KTH, Superseded Departments, Fibre and Polymer Technology.
KTH, Superseded Departments, Fibre and Polymer Technology.ORCID iD: 0000-0002-1922-128X
KTH, Superseded Departments, Fibre and Polymer Technology.
2003 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 41, no 15, 2412-2423 p.Article in journal (Refereed) Published
Abstract [en]

The copolymerization of 1,5-dioxepan-2-one (DXO) and E-caprolactone, initiated by a five-membered cyclic tin alkoxide initiator, was performed in chloroform at 60 degreesC. Copolymers with different molar ratios of DXO (25, 40, and 60%) were synthesized and characterized. C-13 NMR spectroscopy of the carbonyl region revealed the formation of copolymers with a blocklike structure. Differential scanning calorimetry measurements showed that all the copolymers had a single glass transition between -57 and -49 degreesC and a melting temperature in the range of 30.1-47.7 degreesC, both of which were correlated with the amount of DXO. An increase in the amount of DXO led to an increase in the glass-transition temperature and to a decrease in the melting temperature. Dynamic mechanical thermal analysis measurements confirmed the results of the calorimetric analysis, showing a single sharp drop in the storage modulus in the temperature region corresponding to the glass transition. Tensile testing demonstrated good mechanical properties with a tensile strength of 27-39 MPa and an elongation at break of up to 1400%. The morphology of the copolymers was examined with polarized optical microscopy and atomic force microscopy; the films that crystallized from the melt showed a short fibrillar structure (with a length of 0.05-0.4 mum) in contrast to the untreated solution-cast films. (C) 2003 Wiley Periodicals, Inc.

Place, publisher, year, edition, pages
2003. Vol. 41, no 15, 2412-2423 p.
Keyword [en]
1, 5-dioxepan-2-one (DXO), poly(epsilon-caprolactone), thermal properties, mechanical properties, morphology, RING-OPENING POLYMERIZATION
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
URN: urn:nbn:se:kth:diva-13821DOI: 10.1002/pola.10781ISI: 000184076500013OAI: oai:DiVA.org:kth-13821DiVA: diva2:327483
Note
QC 20100629Available from: 2010-06-29 Created: 2010-06-29 Last updated: 2010-06-29Bibliographically approved
In thesis
1. Bioresorbable copolymers with tailored properies: innovative materials för soft tissuel engineering
Open this publication in new window or tab >>Bioresorbable copolymers with tailored properies: innovative materials för soft tissuel engineering
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The emerging need for new synthetic materials for soft tissue engineering applications encourages the search for innovative polymers having interesting properties. Ring-opening polymerization of lactones and lactides initiated by tin alkoxides has received particular attention due to the versatility of the method for building up well-defined biodegradable structures. The controlled reactions together with a careful choice of comonomers and copolymer composition make it possible to create materials with desired molecular architecture and properties.The aim of the work described in this thesis was to design aliphatic bioresorbable copolymers with new structures and controlled properties for potential application in soft tissue engineering. The first part of the work was focused on the surface properties of the materials synthesized for biomedical application. Solution-cast film triblock copolymers of L-lactide (LLA) and 1,5-dioxepan-2-one (DXO), subjected to thermal treatment have been studied. The effects of molecular weight, polymer composition, cooling rate, and casting solution concentration on the nanostructure surface morphology and topography have been investigated by atomic force microscopy (AFM). The surface characterization of the annealed triblock copolymers revealed well-defined fiber features formed as a result of a melt-induced micro-phase separation during crystallization. The dimensions and shape of the formations could be related to the copolymer composition and annealing conditions, and this makes it possible to create controlled and well-defined surface structure. The results of cell adhesion studies on annealed triblock copolymers indicate that these materials favor fibroblast growth and spreading, which makes them promising candidates for applications as bioresorbable membranes.In the next stage of the work, linear and network copolymers of ε-caprolactone (CL) and DXO with a controlled composition and controlled hydrophilicity have been synthesized. The molar fraction of DXO in the copolymers affected their mechanical, thermal and surface properties. The hydrophilicity was tailored by changing the monomer composition in the copolymers. The AFM measurements on the linear copolymers showed that short fibrillar structures were formed upon crystallization from the melt. The supple CL-DXO networks were easy to cast and could easily be removed from the mould surface, so that it is possible to use this material for embossing procedures without the risk of damaging the surface pattern during removal from the mould.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. 70 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2006:18
Keyword
poly(1, 5-dioxepan-2-one), poly(ε-caprolactone), poly(L-lactide), poly(trimethylene carbonate), triblock, network, cyclic tin alkoxide, controlled coordination-insertion ring-opening polymerization, thermoplastic elastomers
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-4042 (URN)91-7178-378-4 (ISBN)
Public defence
2006-06-16, Aal K2, Teknikringen 28, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100629Available from: 2006-06-07 Created: 2006-06-07 Last updated: 2010-06-29Bibliographically approved

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