Smart Polyurethane Shape Memory Polymers

Shape memory polymers (SMPs) have attracted great deal of attention from scientists and researchers during the last twenty years, due to their peculiar ability to maintain two shapes under different conditions. These materials have the ability to return to their original shape by application of an external stimulus. The external stimuli may be light, water, heat, chemical, electrical field or magnetic field. Most common SMPs are activated by the application of heat for which they are also termed as "temperature sensitive" or "thermal responsive" polymers. The changes in shape introduced by heating are called thermally induced shape memory effect which has been observed in a variety of materials. There are various shape memory materials, including shape memory alloys (SMAs), ceramics, polymers and gels. Among these, the shape memory alloys and SMPs are the most popular and studied ones.