Shape memory polyurethane or polyurethane-urea polymers
A shape memory polyurethane or polyurethane-urea polymer including a reaction product of: (A) (a) silicon-based macrodiol, silicon-based macrodiamine and/or polyether of the formula (I): A—[(CH 2 ) m —O] n —(CH 2 ) m —A′, 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; or (B) (b) a diisocyanate: and (c) a chain extender, said polymer having a glass transition temperature which enables the polymer to be formed 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. The present invention also relates to a shape memory composition which includes a blend of two or more of the shape memory polyurethane or polyurethane-urea polymers defined above or at least one shape memory polyurethane or polyurethane-urea polymer defined above in combination with another material. The present invention further relates to processes for preparing materials having improved mechanical properties, clarity, processability, biostability and/or degradation resistance and devices or articles containing the shape memory polyurethane or polyurethane-urea polymer and/or composition defined above.
1. 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.
2. A shape memory polyurethane or polyurethane-urea polymer according to claim 1 , wherein z is an integer of 0 to about 50, x is an integer of 1 to about 50, m is an integer of 0 to about 20 and y is an integer of 0 to about 10.
3. A shape memory polyurethane or polyurethane-urea polymer according to claim 1 , wherein the silicon-based polycarbonate is a compound of the formula (IV) wherein the endcapping group is a hydroxy which is a polycarbonate macrodiol of the formula (IVa):
4. A shape memory polyurethane or polyurethane-urea polymer according to claim 3 , wherein the polycarbonate macrodiol is a compound of the formula (IVa) wherein R 1 , R 2 , R 3 and R 4 are methyl, R 8 is ethyl, R 9 is hexyl, R 5 and R 6 are propyl or butyl and R 7 is O or —CH 2 —CH 2 —.
5. A shape memory polyurethane or polyurethane-urea polymer according to claim 4 wherein R 5 and R 6 are propyl when R 7 is O and R 5 and R 6 are butyl when R 7 is —CH 2 —CH 2 —.