Synthesis of Self-Healing Elastomers by Scandium-Catalyzed Terpolymerization of Ethylene, Styrene, and Dimethylaminophenyl-Substituted Propylene

The synthesis of self-healing polymers by catalyst-controlled copolymerization of commodity olefins is of fundamental interest and practical importance but remains highly challenging. We report here the synthesis of a new family of self-healing elastomers through terpolymerization of ethylene (E), styrene (St), and dimethylaminophenyl-substituted propylene (AMP) using a sterically demanding half-sandwich scandium catalyst. The terpolymers, comprising AMP–alt–(E–E) sequences and St–St and E–E blocks, exhibited excellent elasticity and rapid self-healing properties. Notably, employing 4-tert-butylstyrene instead of unsubstituted styrene in the terpolymerization yielded the corresponding terpolymers with further enhanced mechanical strength and self-healing capabilities. X-ray diffraction analyses and scanning transmission electron microscopy (STEM) images of an E–St–AMP terpolymer revealed a nanophase-separated structure comprising crystalline E–E and glassy amorphous St–St nanodomains dispersed in a rubbery AMP–E–E matrix, providing insights into its remarkable mechanical and self-healing properties. This work represents a significant advancement in the synthesis of olefin-based self-healing polymers with potential applications in various fields.