Patent ID: 6858680

Claim:
A biostable shape memory polyurethane or polyurethane-urea polymer comprising a reaction product of (a), (b) and (c) as set out below: (a) a silicon-based macrodiol and a polyether of formula (I) below; a silicon-based macrodiamine and a polyether of formula (I) below; or a silicon-based microdiol, a silicon-based macrodiamine and polyether of formula (I): A(CH 2 ) m —O n (CH 2 ) m —A′ (I) wherein A and A′ are endcapping groups; m is an integer of 6 or more; and n is an integer of 1 or greater, (b) a diisocyanate; and (c) a chain extender, wherein the silicon-based macrodiol and macrodiamine are silicon-based polycarbonates having the formula (IV): wherein: R 1 , R 2 , R 3 and R 4 are the same or different and selected from hydrogen or an optionally substituted straight chain, branched chain and cyclic, saturated or unsaturated hydrocarbon radical; R 5 , R 6 , R 8 and R 9 are the same or different and selected from an optionally substituted straight chain, branched chain and cyclic, saturated or unsaturated divalent hydrocarbon radical; R 7 is a divalent linking group or an optionally substituted straight chain, branched chain or cyclic, saturated or unsaturated hydrocarbon radical; A and A′ are as defined in formula (I); m, y and z are integers of 0 or more; and x is an integer of 0 or more said polymer having a glass transition temperature which enables the polymer to be transformed from its original shape into a first shape at a temperature higher than the glass transition temperature and maintained in said first shape when the polymer is cooled to a temperature lower than the glass transition temperature, said polymer then being capable of resuming its original shape on heating to a temperature higher than the glass transition temperature.