A class of degradable, phase-segregated multiblock copolymers is presented. The new copoly(ester-urethane)s, termed DegraPol / btgc, consist of crystallizable poly[(3-R-hydroxybutyrate)-co-(3-R-hydroxyvalerate)]-segments and amorphous segments from e-caprolactone, diglycolide and ethylene glycol. As junction unit an aliphatic diisocyanate, TMDI, is applied. The copoly(ester-urethane)s are thermoplastic elastomers (T m = 120-136°C) and are processable without degradation. For medical applications, materials are needed in which the degradation rate and the mechanical properties are independently adjustable to the medical needs. The mechanical properties of DegraPol / btgc, e.g., elasticity and toughness, can be controlled by the weight fraction of crystallizable segment; the elastic moduli of DegraPol/btcg are adjustable between 50 MPa and 500 MPa and were only little influenced by the chemical structure and the composition of the soft segment. By insertion of 'weak links' in the form of easily hydrolyzable glycolyl-glycolate ester bonds into the amorphous segments, we attempted to synthesize degradable polymers in which the hydrolytic degradation rate can be controlled by the amount and the sequence distribution of these bonds. We report on the synthesis and on the thermal and mechanical properties of such polymers.
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