Styrene Moiety-Carrying Diorganozinc Compound Preparation for Polystyrene-Poly(ethylene-<i>co</i>-1-hexene)-Polystyrene Triblock Copolymer Production
Jong Chul Lee, Kyung Lee Park, Sung Moon Bae, Hyun Ju Lee, Jun Won Baek, Junseong Lee, Seokpil Sa, Eun Ji Shin, Ki Soo Lee, Bun Yeoul Lee
Abstract
Polystyrene (PS)-block-poly(ethylene-co-1-butene)-block-PS (SEBS), produced by PS-block-polybutadiene-block-PS hydrogenation, is a high-performance thermoplastic elastomer. Hydrogenation is costly and tedious, making SEBS market expansion difficult. Thus, we envisioned a new one-pot SEBS-like triblock copolymer synthetic scheme to grow PO chains from styrene moiety-carrying diorganozinc compounds by coordinative chain transfer polymerization (CCTP), followed by anionic styrene polymerization using a specially designed initiator, allowing PS chain growth from not only the styrene moieties but also the Zn–C sites. Large-scale preparation of highly pure styrene moiety-carrying diorganozinc compounds was one of the main challenges we faced, but we overcame it by synthesizing (CH2═CHC6H4CH2CH2CH2)2Zn (4), a stable and crystalline solid that worked well as a CCTP agent. This enabled the preparation of PS-block-poly(ethylene-co-1-hexene)-block-PS (SEHS), which exhibited a stress–strain curve similar to that of the commercial-grade SEBS. The SEHS dispersed better in a polypropylene (PP) matrix, allowing it to act as a better toughening agent for PP blending than the commercial-grade SEBS. Moreover, SEHS was less viscous, exhibiting better workability.