Mechanical Models, Structures, and Applications of Shape-Memory Polymers and Their Composites

Shape-memory polymers (SMPs) and their composite materials are stimuli-responsive materials that have the unique characteristics of lightweight, large deformation, variable stiffness, and biocompatibility. This paper reviews the research status of the mechanical models for SMPs, shape-memory nanocomposites and shape-memory polymer composites (SMPCs); it also introduces some spatially deployable structures, such as hinges, beams, and antennae based on SMPCs. In addition, the deformation types of 4D printing structures and the potential applications of this technology in robots and medical devices are also summarized.