AbstractShape-memory polymers are an emerging class of active polymers that have dual-shape capability. They can change their shape in a predefined way from shape A to shape B when exposed to an appropriate stimulus. While shape B is given by the initial processing step, shape A is determined by applying a process called programming. We review fundamental aspects of the molecular design of suitable polymer
architectures, tailored programming and recovery processes, and the
quantification of the shape-memory effect. Shape-memory research
was initially founded on the thermally induced dual-shape effect. This concept has been extended to other stimuli by either indirect thermal actuation or direct actuation by addressing stimuli-sensitive groups
on the molecular level. Finally, polymers are introduced that can
be multifunctional. Besides their dual-shape capability, these active materials are biofunctional or biodegradable. Potential applications for such materials as active medical devices are highlighted.