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 ( A R P ) monomers by a scandium catalyst. The results reveal that steric matching drives quasi-alternating insertion of ethylene and A R P comonomer, leading to the formation of predominant E - alt - A R P sequences, while electronic effects govern the competitive selectivity among different A R P monomer pairs. When A R P monomer pairs possess similar electronic properties (e.g., A Hex P vs A Naph P ), random-type terpolymers ( E - A Hex P - random - E - A Naph P ) are obtained. In contrast, when AP monomer pairs exhibit significant electronic differences (e.g., electron-donating A Me/Hex P and electron-withdrawing A F/Cl P ), block-type terpolymers E-A Me/Hex P - block - E-A F/Cl P are formed. Experimentally synthesized block-type terpolymer E-A Me P - block - E-A F P demonstrates high toughness and rapid self-healing capability, with the E - A Me P block contributing to mechanical strength and the E - A F P 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.