Recent progress in shape memory polymer composites: Driving modes, forming technologies, and applications

Shape-memory polymers (SMPs) are smart materials that can recover their original shapes from temporary ones under external stimuli. In recent years, various types of shape-memory polymer composites (SMPCs) have emerged, which not only expand the functionality of SMPs but also enhance their mechanical properties. It is crucial for SMPs and their composites to talk about the relationship between materials, moulding techniques, and applications. SMPs and their composites can achieve responses under electrical, magnetic, optical, and other stimuli, allowing for selective responses. These materials can be combined with a variety of technologies in diverse forms for wider application in different fields. This paper briefly introduces the SMPs and their shape memory mechanism and discusses SMPCs according to the type of filler. We then describe SMPs and their composites with different driving modes, which can result in varied application scenarios. The use of 4D printing technology, electrospinning technology, and micro/nano-pattern technology in SMPs and their composites, as well as the applications of SMPs and their composites in biomedical, aerospace, electronics, robotics, optics, and other fields have been demonstrated. Thus, SMPs and their composites will continue to play important roles as smart materials.