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Potential tissue implants from the networks based on 1,5-dioxepan-2-one and epsilon-caprolactone
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2005 (English)In: Polymer journal, ISSN 0032-3896, E-ISSN 1349-0540, Vol. 46, no 18, p. 6746-6755Article in journal (Refereed) Published
Abstract [en]

The synthesis and characterization of degradable polymeric networks for biomedical applications was performed. Cross-linked films of poly(epsilon-caprolactone) (PCL) and poly(1,5-dioxepan-2-one) (PDXO) having various mole fractions of monomers and different cross-link densities were successfully prepared using 2,2'-bis-(epsilon-caprolactone-4-yl) propane (BCP) as cross-linking agent. Reaction parameters were carefully examined to optimise, the film-formin.,, conditions. Networks obtained were elastomeric materials. easy to cast and remove from the mould. Effect of CL content and cross-link density on the final properties of the polymer network was evaluated. High CL content or degree of cross-linking led to increase in Young's modulus and decrease in elongation at break. An increase in crystalline domains in films having a higher CL content was observed by optical microscopy. A greater thermal stability was observed in films having a high CL content. The hydrophilicity of the materials could be tailored by changing the CL content. The surface of the films became rougher with higher CL content.

Place, publisher, year, edition, pages
2005. Vol. 46, no 18, p. 6746-6755
Keyword [en]
Characterization, Crosslinking, Degradation, Implants (surgical), Monomers, Plastic films, Synthesis (chemical), Tissue, 1, 5-dioxepan-2-one, Biomedical applications, Cross-linking agents, Organic polymers
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-8817DOI: 10.1016/j.polymer.2005.06.038ISI: 000231397200003Scopus ID: 2-s2.0-23744514731OAI: oai:DiVA.org:kth-8817DiVA, id: diva2:14263
Note
QC 20100629Available from: 2005-11-24 Created: 2005-11-24 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Novel methods to synthesize aliphatic polyesters of vivid architectures
Open this publication in new window or tab >>Novel methods to synthesize aliphatic polyesters of vivid architectures
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Cross-linked films of ε-caprolactone (CL) and 1,5-dioxepan-2-one (DXO) having various mole fractions of monomers and different cross-link densities were prepared using 2,2’-bis-(-caprolactone-4-yl) propane (BCP) as cross-linking agent and Sn(Oct)2 as catalyst. Reaction parameters were examined to optimize the film-forming conditions. Networks obtained were elastomeric materials, easy to cast and remove from the mould. Effect of CL content and cross-link density on the final properties of the polymer network was evaluated. Thermal, mechanical and surface properties of the films were controlled by monomer feed composition and cross-link density. The films have potential to be used for tissue engineering applications as shown by preliminary cell growth studies. To avoid organometallic catalysts in the synthesis of poly(1,5-dioxepan-2-one) (PDXO), the enzyme-catalyzed ring-opening polymerization (ROP) of DXO was performed with lipase-CA (derived from Candida antarctica) as a biocatalyst. A linear relationship between number-average molecular weight (Mn) and monomer conversion was observed, which suggested that the product molecular weight can be controlled by the stoichiometry of the reactants. The monomer consumption followed a first-order rate law with respect to monomer and no chain termination occurred. Effect of reaction water content, enzyme concentration and polymerization temperature on monomer conversion and polymer properties was studied. An initial activation by heating the enzyme was sufficient to start the polymerization as monomer conversion occurred at room temperature afterwards. Terminal-functionalized polyesters and tri-block polyesters were synthesized by lipase-CA catalyzed ROP of DXO and CL in the presence of an appropriate alcohol as initiator. Alcohol bearing unsaturation introduced a double bond at the chain end of the polyester, which is a useful pathway to synthesize comb polymers. Dihydroxyl compounds were used as macro-initiators to form tri-block polyesters. The enzyme-catalyzed polymerization of lactones has been shown to be a useful method to synthesize metal-free polyesters.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. p. 84
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2005:38
Keyword
Polyesters, 1, 5-dioxepan-2-one, Caprolactone, Sn(Oct)2, Enzyme, Lipase-CA, Ring-Opening Polymerization, Architecture, Tissue Engineering
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-511 (URN)91-7178-191-9 (ISBN)
Presentation
2005-12-02, E2, Huvudbyggnaden, Lindstedtsvägen 3, Entreplan KTH, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101221Available from: 2005-11-24 Created: 2005-11-24 Last updated: 2010-12-21Bibliographically approved
2. 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. p. 70
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
3. Aliphatic Polyesters for Soft Tissue Engineering: Development from Conventional Organometallic to Novel Enzymatic Catalysis
Open this publication in new window or tab >>Aliphatic Polyesters for Soft Tissue Engineering: Development from Conventional Organometallic to Novel Enzymatic Catalysis
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The development of macromolecules with defined structure and properties, aimed specifically for biomedical applications, has resulted in diverse biodegradable polymers with advanced architectures. Among them, aliphatic polyesters synthesized by ring-opening polymerization (ROP) of lactones and lactides have a leading position due to their good mechanical properties, hydrolyzability and biocompatibility. To achieve tailored properties and controlled architecture, the technique for ROP of lactones and lactides has been continuously refined in the past years. Enzyme-catalyzed ROP is one of the most promising tools, which avoids the use of toxic organometallic catalysts and brings a “green-chemistry” appeal with it. In the work described in this thesis, enzyme-catalyzed ROP of 1,5-dioxepan-2-one (DXO), ε-caprolactone (CL) and lactides (L-, D- and D,L-lactide) was performed in bulk using Lipases from different sources. The effects of enzyme concentration, polymerization temperature and reaction water content on the monomer conversion and the polymer molecular weight during DXO polymerization were studied, and the role of water as initiator was confirmed. Terminal functionalized, block, comb and star polymers were synthesized using different alcohols as initiator in the enzyme-catalyzed ROP of DXO, CL or lactides under strictly anhydrous conditions. The effect of simultaneous and sequential copolymerization of DXO and CL on the micro-block structure of the copolymers was studied and the reactivity ratios of DXO and CL were determined under Lipase catalysis. High molecular weight copolymers of DXO and CL thus obtained were fabricated into porous scaffolds for tissue implant applications. Enzymatic degradation and alkaline hydrolysis of lactides was performed to study the effect of molecular branches and the stereochemistry of the monomer on the degradation profile. In another approach, cross-linked films of DXO and CL were prepared using 2,2´-bis-(ε-caprolactone-4-yl) propane (BCP) as the cross-linking agent and Sn(Oct)2 as the catalyst. The networks obtained thereof were elastomeric materials, easy to cast and remove from the mould.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. p. 125
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2007:2
Keyword
aliphatic polyester, 1, 5-dioxepan-2-one, ε-caprolactone, L-lactide, D-lactide, D, L-lactide, enzyme, lipase CA, lipase PS
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-4341 (URN)978-91-7178-595-4 (ISBN)
Public defence
2007-05-04, F3, KTH, Lindstedtsvägen 26, Stoclholm, 10:15
Opponent
Supervisors
Note
QC 20100818Available from: 2007-04-20 Created: 2007-04-20 Last updated: 2011-02-21Bibliographically approved

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