Stereoselective Control of Crystalline Alternating Copolymers Synthesized with an Anion-Migrated Ring-Opening Polymerization Method

Developing synthetic methods and achieving precise control over the crystallization behavior of copolymers remain fundamental challenges in polymer chemistry. Herein, strictly alternating copolymers were prepared through the alternating copolymerization of 1-cyclopropylvinylbenzene/1-cyclobutylvinylbenzene (CPVB/CBVB) with 1,1-diphenylethylene (DPE) under ideal alternating copolymerization kinetics (kDD, kCC = 0). The E-configuration content in the CPVB/DPE alternating copolymer (C2-alt-C5) chains was enhanced by adding tetrahydrofuran (THF) as an additive or increasing the concentration of the carbanion active center during polymerization. The CPVB/DPE alternating copolymer only exhibits crystallinity (Xc > 9.8%) when its E-configuration content exceeds 93%. In contrast, the CBVB/DPE alternating copolymer (C2-alt-C6) exhibits significant crystallinity (Xc = 76.7%) with higher Z-configuration content (47.6%). This finding not only advances synthetic methodologies for crystalline alternating polymers but also addresses the long-standing challenge of precisely modulating crystallization capabilities in living anionic polymerization systems.