Shape-Memory and Self-Healing Polymers Based on Dynamic Covalent Bonds and Dynamic Noncovalent Interactions: Synthesis, Mechanism, and Application

Abstract

Shape-memory and self-healing polymers have been a hotspot of research in the field of smart polymers in the past decade. Under external stimulation, shape-memory and self-healing polymers can complete programed shape transformation, and they can spontaneously repair damage, thereby extending the life of the materials. In this review, we focus on the progress in polymers with shape-memory and self-healing properties in the past decade. The physical or chemical changes in the materials during the occurrence of shape memory as well as self-healing were analyzed based on the polymer molecular structure. We classified the polymers and discussed the preparation methods for shape-memory and self-healing polymers based on the dynamic interactions which can make the polymers exhibit self-healing properties including dynamic covalent bonds (DA reaction, disulfide exchange reaction, imine exchange reaction, alkoxyamine exchange reaction, and boronic acid ester exchange reaction) and dynamic noncovalent interactions (crystallization, hydrogen bonding, ionic interaction, metal coordination interaction, host-guest interactions, and hydrophobic interactions) and their corresponding triggering conditions. In addition, we discussed the advantages and the mechanism that the shape-memory property promotes self-healing in polymers, as well as the future trends in shape-memory and self-healing polymers.

Keywords: dynamic interaction; polycaprolactone; polylactide; polyurethane; transition temperature.