Fundamentals of Molecular Design and Preparation of Temperature-sensitive Shape Memory Polymers: A Review

Shape memory polymers been developed in the past years as a valid alternative to more traditional shape-memory materials. Shape memory polymers belong to a class of very smart materials that have the ability to remember their original shape. This advanced functionality makes shape memory polymer suitable and promising materials for diverse technological applications, including sensors and actuators particularly including the fabrication of smart biomedical devices. The polymers deform into a temporary shape and returns to its original shape by external environmental stimuli such as chemicals, temperature or pH. Therefore, a temperature-sensitive shape memory polymer is one that undergoes a structural change at a certain temperature called the transition temperature. A change in shape caused by a change in temperature is called a thermally-induced 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. This paper is intended to serve as a brief review of key concepts associated with shape memory material. This review describes the fundamental aspects of molecular design of suitable polymer architectures, tailored programming and recovery processes, with the focus being on the structure of thermally sensitive shape memory polymers.