Shape Memory Polymers

Abstract

The shape memory polymer (SMP) concept has been developed to handle the varied shapes of one article so that the difficulty in transportation of the article in its normal shape is overcome. After the shape memory alloy was found to perform various smart activities, shape memory polymers were developed. After describing the principle of shape memory, this chapter discusses SMPs with high recovery stress and ultrahigh molecular weight. Some examples of the architecture of shape memory polymers, such as physically cross-linked glassy copolymers, semi-crystalline cross-linked polymers, physically cross-linked semi-crystalline block copolymers, are given. The recovery stress, strain, strain fixicity, etc. are correlated with different architectures. SMPs with a multi-shape memory effect are of great practical use in many fields. Multiple factors governing the efficiency and their clinical safety are considered for in vivo applications of SMP. Two-way reversible shape memory polymers have many commercial applications. Activation of shape memory can be done from a remote location by using light. Water- and solvent-driven shape memory effects, constituting a special class of SMPs, are discussed in the chapter. There are special types of shape memory polymers, including high- and low-temperature-resistant polymers, porous polymers and polymers with an organic coating, offering many possibilities for applications. Shape memory polymer composites, including electroactive polymers, and various types of filler incorporation are discussed in detail. SMPs with a self-healing ability offer dual application possibilities. Magnetic nanocomposites, SMP textiles, fibers, fabrics, two-way shape memory fabrics, damping fabrics, super-hydrophobic fabrics, etc. are another field of development. Phase change SMPs, such as SMP hydrogels, have tremendous health care application possibilities. Considering health care and environmental concerns, biodegradable SMPs are also included. For nerve tissue engineering applications, a porous shape memory scaffold with both biomimetic structures and electrical conductivity has important functions. Using SMPs in 3D printing offers many possibilities, with various design strategies achieving important and useful architectures. Finally, the characteristics of SMPS are detailed.