4-1 Introduction

Abstract

Shape-memory polymers (SMP) have received increasing attention in recent years on account of their interesting properties and potential applications. Such applications include medical devices, actuators, sensors, artificial muscles, switches, smart textiles and self-deployable structures [1–4]. Increasing numbers of scientists and engineers are turning to the design of new SMP for more extensive and in-depth applications. According to the mechanism of action of shape-memory, the features of SMP should include a transition that can be used to fix the secondary shape at low temperatures and trigger shape recovery at high temperatures, elasticity for shape recovery above the transition temperature, and ability of fixing the temporary shapes [1]. Based on the concept, SMP can be divided into four main classes [2], as described below. 1. Covalently crosslinked glassy thermoset networks are the simplest type of SMP. The rubbery elasticity derived from covalent crosslinks elicits excellent shape recovery, which is tunable through adjustment of the extent of covalent crosslinking. However, the covalently fixed primary shape makes it difficult to reshape thereafter once processed.