Self-Healing and Shape-Memory Multiphase Thermoplastic Elastomers Based on Electrostatic Assembly of Oppositely Charged Diblock Copolymer Assemblies

Shape-memory and self-healing thermoplastics are a vital family of engineering polymers, potentially enabling reshaping, reuse, and recycling. In this study, we report supramolecular thermoplastic elastomers consisting of oppositely charged aggregates having a hard polystyrene core and a soft charged poly(n-butyl acrylate) based corona that forms the soft matrix by electrostatic interactions. Therefore, a series of well-defined diblock copolymers, namely, polystyrene-b-poly(butyl acrylate-co-2-(dimethylamino)ethyl acrylate) and polystyrene-b-poly(butyl acrylate-co-2-carboxyethyl acrylate), with varying number-average molecular weights and compositions were synthesized by RAFT polymerization. The supramolecular thermoplastics were constructed by mixing these two polymers in the presence of a small amount of water to induce aggregation, followed by solvent evaporation at room temperature leading to microphase separation of vitrified spherical polystyrene domains in an electrostatically cross-linked soft poly(n-butyl acrylate) matrix. These thermoplastics were mechanically tough and stretchable, with a storage modulus of 40 kPa from rheology and a tensile stress of 500 kPa. Furthermore, these supramolecular materials exhibit good thermal processability and moldability into various desired shapes (e.g., film, disc, etc.). More importantly, the thermoplastics also have shape-memory ability as well as self-healing ability at 70 °C for 30 min or during cyclic strain sweep measurements within seconds without any external manipulation. This work opens up avenues toward constructing multifunctional shape memory and self-healing materials for various applications.