Scandium-Catalyzed Sequence-Regulated Terpolymerization of Ethylene and Anisylpropylenes toward Self-Healing Elastomers: A Combined Experimental and DFT Study

The precise control of copolymer microstructure, particularly to achieve self-healing polyolefins, remains a formidable challenge in the copolymerization of ethylene with polar monomers. This study combines experimental investigation with density functional theory (DFT) calculations to elucidate the mechanism of sequence-regulated terpolymerization of ethylene (E) with two distinct anisylpropylene (ARP) monomers by a scandium catalyst. The results reveal that steric matching drives quasi-alternating insertion of ethylene and ARP comonomer, leading to the formation of predominant E-alt-ARP sequences, while electronic effects govern the competitive selectivity among different ARP monomer pairs. When ARP monomer pairs possess similar electronic properties (e.g., AHexP vs ANaphP), random-type terpolymers (E-AHexP-random-E-ANaphP) are obtained. In contrast, when AP monomer pairs exhibit significant electronic differences (e.g., electron-donating AMe/HexP and electron-withdrawing AF/ClP), block-type terpolymers E-AMe/HexP-block-E-AF/ClP are formed. Experimentally synthesized block-type terpolymer E-AMeP-block-E-AFP demonstrates high toughness and rapid self-healing capability, with the E-AMeP block contributing to mechanical strength and the E-AFP block enabling fast repair, synergistically optimizing material performance. This work provides mechanistic insights into the relationships among steric/electronic effects, sequence structures, and material properties, thereby providing theoretical insights and synthetic strategies for the rational design of high-performance self-healing polyolefins.