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.