A series of degradable poly(propylene oxide)-poly(L-lactide)-polyurethane (POLA-PU) shape memory polymers were synthesized by crosslinking triarm POLA diblock copolymers with tolylene diisocyanate (TDI). The mechanical properties of POLA-PU could be conveniently adjusted through variation of composition to prepare materials from high modulus and low elongation at break to low modulus and high elongation at break. The transition temperatures of POLA-PU were between 96 and 153 ℃ by thermomechanical analysis (TMA) and the restoration time was less than 20 s in 140 ℃. When the deformations from the permanent to the temporary shape were up to 200%, POLA-PU samples had a shape fixity rate between 65% and 100% and a shape recovery rate of 100%. Shape memory behavior relies on the cross-linking densities, and this effect can be achieved with changing conformational entropy of soft chains in different temperatures. The degradation of POLA-PU was investigated in 10% NaOH at 80 ℃. The results showed that the PLLA segments were introduced to novel shape memory materials with the degradable property, and the rate of degradation was decreased with decreasing the PLLA segments content.

Key words: polyether, polylactide, polyurethane, shape memory, degradation