Shape memory effects in self-healing polymers

Recent developments in self-healing polymers (SHPs) have been fueled by the increasing need for sustainable materials with extended life-spans and functionality. This review focuses on the shape memory effect (SME) in polymers and its contribution to self-healing. Starting from structural requirements and thermodynamics, quantitative aspects of the SME are discussed in the context of energy storage and release during the damage-repair cycle. Characterization of shape memory in polymers has largely concentrated on recovery and fixation ratios, which describe the efficiency of the geometrical changes. In this review, factors that govern strain, stress, and energy storage capacities are also explored. Of particular interest for self-healing are deformability and conformational entropic energy storage and release efficiency during reversible plasticity shape memory (RPSM) cycles. Physical and chemical mechanisms of strength regain following shape recovery as well as other physical factors that influence the self-healing process are also discussed.