Biaxial Chain Growth of Polyolefin and Polystyrene from 1,6-Hexanediylzinc Species for Triblock Copolymers

• DOI: 10.1021/acs.macromol.7b01365
• Publication Date: 2017-08-21T17:09:22Z
• Authors: Seung Soo Park; Chung Sol Kim; Sung Dong Kim; Su Jin Kwon; Hyun Mo Lee; Tae Hee Kim; Jong Yeob Jeon; Bun Yeoul Lee
• Keywords: Polyolefin; Polystyrene; Chain (unit); Long chain

Synthesis of polyolefin (PO)-based block copolymers is immense research interest. In this work, we report a strategy for the construction polystyrene (PS)-block-PO-block-PS, useful thermoplastic elastomer, directly from olefin and styrene monomers. Multinuclear zinc species Et[Zn(CH2)6]aZnEt were prepared through successive additions BH3 Et2Zn to 1,5-hexadiene. Poly(ethylene-co-propylene) chains biaxially grown −(CH2)6– units in via "coordinative chain transfer polymerization (CCTP)" using pyridylaminohafnium catalyst. PS subsequently one pot generated polymeryl–Zn sites by subsequent introduction anionic initiator Me3SiCH2Li·(pmdeta) (pmdeta, pentamethyldiethylenetriamine) The fraction extracted homopolymer Me3SiCH2 was low (homo-PS (g)/total (g), 15–22%). gel permeation chromatography (GPC) curves shifted evidently after polymerization, change molecular weight (ΔMn, 39–56 kDa) approximately twice homo-PS Mn (20–23 kDa), accordance with attachment at both ends PO chains. Transmission electron microscopy analysis thin films showed segregation domains matrix form spherical or wormlike rippled structures depending on content. triblock exhibited elastomeric properties cyclic tensile test, similar commercial PS-block-poly(ethylene-co-1-butene)-block-PS.