ABSTRACT
Polymers that are able to "memorize" a permanent shape and can be manipulated so that a certain temporary shape will be "fixed" under appropriate conditions are called shape memory polymers (SMPs). The transformation is stimulated by temperature changes across the transition temperature of the polymer. Application-driven industrial research is now complemented by academic research, which has begun to investigate the underlying mechanisms and design principles of these materials. The mechanism of SMPs is totally different from the martensitic phase transition of shape memory alloys or ferroelectric phase transition of shape memory ceramics. Entropy elasticity, a property of SMPs that releases polymeric chains from their strained configuration to a less complex configuration, acts as an impetus for shape memory realization. Chain mobility is a vital component in SMP behavior that in turn depends on the viscosity of monomers and the interactions between them.
