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Synthesis of highly elastic biodegradable poly(urethane urea)
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 3, 905-911 p.Article in journal (Refereed) Published
Abstract [en]

Linear poly(urethane urea) containing a biodegradable soft segment and a hard segment built solely from methyl-2,6-diisocyanatehexanoate (LDI) is presented, using a procedure where no chain extender is required. By having LDI in excess, together with a soft segment, and adding water in the vapor phase continuously creates amines in situ resulting in hard segments containing multiple LDI units linked via urea linkages. As soft segments, polymers of trimethylene carbonate (TMC) and copolymers of TMC, ε-caprolactone, and d,l-lactic acid (DLLA) were used. High inherent viscosity, 0.95−1.65 dL/g, was afforded even when DLLA-containing soft segments were used, which usually undergo aminolysis. With a hard segment content between 12% and 18%, all of the materials showed very high elongation at breakage, ranging from 1600% to 4700%, and an elastic modulus from 2.1 to 140 MPa. This one-pot synthesis is simple and has now been shown to be applicable to a large number of systems.

Place, publisher, year, edition, pages
2007. Vol. 8, no 3, 905-911 p.
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-95334DOI: 10.1021/bm061058uISI: 000244798600019OAI: oai:DiVA.org:uu-95334DiVA: diva2:169507
Available from: 2007-01-08 Created: 2007-01-08 Last updated: 2011-02-10Bibliographically approved
In thesis
1. Biodegradable Thermoplastic Elastomers
Open this publication in new window or tab >>Biodegradable Thermoplastic Elastomers
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A novel strategy for synthesising segmented poly(urethane urea) (PUU) without using a chain extender but nevertheless with the opportunity to vary the hard segment content has been developed. The strategy is based on amine formation from isocyanate upon reaction with water. By adding a dissolved soft segment to an excess of diisocyanate followed by the addition of water in the gas phase, amines are formed in situ. Urea linkages are then formed when these amines react with the excess of isocyanate groups. The gas phase addition facilitates addition in a slow and continuous manner. The hard segment content can easily altered by varying the diisocyanate/soft segment ratio. Even though the strategy is shown to be applicable to different diisocyanates, the focus has been on the potentially biodegradable methyl-2,6-diisocyanatehexanoate (LDI) and 1.4-butanediisocyanate (BDI) and various well known biodegradable polyesters and polycarbonates.

All the synthesised materials exhibited pronounced phase separation and hydrogen bonding within the hard domains. However, a major increase in hydrogen bonding strength was seen when a symmetric diisocyanate was used instead of an asymmetric. Based on FTIR measurements, PUUs with BDI and a polydisperse hard segment can exhibit the same degree of phase separation and hydrogen bonding as the monodisperse product.

The elastic properties of this new group of PUUs were exceptional with an elongation at break from 1600% to almost 5000% and the elastic modulus could be varied from a few MPa up to a couple of hundreds.

Hydrolytic degradation was greater in the polyester-based than in the polycarbonate-based PUUs due to the more reactive ester bonds. Low mass loss but a considerable loss in molecular weight was seen in the polyester PUUs. The tensile strength decreased dramatically due to the loss of strain hardening.

An MTT seeding assay using human fibroblasts and an in vivo biocompatibility study were performed and no signs of cytotoxicity were seen and the inflammatory response was comparable to other inert polymers.

A biodegradable PUU with properties that can be tailored through an easy synthesis is here presented.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 81 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 268
Chemistry, poly(urethane), poly(urethane urea), biomaterial, biodegradable, polymer, thermoplastic elastomer, haemocomatible, tissue engineering, biocompatible, Kemi
urn:nbn:se:uu:diva-7434 (URN)978-91-554-6771-5 (ISBN)
Public defence
2007-01-27, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 14:00
Available from: 2007-01-08 Created: 2007-01-08Bibliographically approved

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Asplund, J. O. BasseBowden, Tim
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