Amorphe bioabbaubare Poly(esterurethan)netzwerksysteme mit Formgedächtniseigenschaften

This work describes the synthesis and characterization of completely amorphous and covalently crosslinked polymer systems with shape-memory properties. The macroscopic properties of the polymer networks can be tailored by variation of molecular parameters such as chemical composition, crosslink density or functionality of the crosslink points. The hydrolytic degradable polymer networks are conceived for medical applications. Covalently crosslinked single-phase polymer networks are synthesized via a two-step reaction. Star-shaped hydroxytelechelic oligomers are initially prepared as precursors by ring-opening copolymerization of rac-dilactide and diglycolide, E-caprolactone or p-dioxanone. Covalent networks are formed by polyaddition of precursors and a diisocyanate acting as coupling agent. The glass transition temperature Tg of the networks corresponds to the transition temperature Ttrans of the shape-memory effect. The thermal properties are mainly determined by the chemical structure and the content of the comonomers. Mechanical properties of the networks are clearly influenced by Tg. At temperatures evidently above Tg, mechanical characteristics depend on the crosslink density. Cyclic thermomechanical tensile experiments reveal a nearly quantitative fixation of the deformed temporary shape and recovery of the permanent shape. Hydrolytic degradation experiments are carried out at pH 7 and 37 °C in an aqueous phosphate buffer solution. The onset of the mass loss can be controlled by the comonomer ratio. Beside the single-phase systems multiphase-polymer networks with two separate glass transition temperatures are synthesized. These materials exhibit a rubber-elastic phase beside domains consisting of oligo[(rac-lactate)-co-glycolate]segments serving as switching segments. The additional phase is formed by oligo(propylene glycol) or poly(acrylate)segments. Tailoring the mechanical properties of the materials below Ttrans can be achieved by variation of the rubber-elastic phase content. The multiphase-polymer networks show an almost complete fixation of the temporary shape and recovery of the permanent shape.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2003

Author dc:creator

• Alteheld, Armin

Contributors dc:contributor

• Höcker, Hartwig

• info:eu-repo/classification/ddc/540
• Polyesterpolyurethane
• Polymeres Netzwerk
• Amorphe Polymere
• Memory-Effekt
• Mikrobielle Abbaubarkeit
• Chemie
• Polymer
• Netzwerk
• bioabbaubar
• Formgedächtnis

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120882%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:59066