Well-defined 4-arm stars with hydroxy-terminated polyethylene, polyethylene-b-polycaprolactone and polyethylene-b-(polymethyl methacrylate)(2) arms

摘要

Bis-boron-thexyl-silaboracycle was prepared by hydroboration of 1,4-bis(methyldivinylsilyl) butane with thexylborane and used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined hydroxy-terminated 4-arm polyethylene (PE) stars. The synthesized PE stars were transformed to (PE-b-PCL)(4) starblock copolymers via the ring-opening polymerization of e-caprolactone (CL) initiated by the hydroxyl end groups of (PE-OH)(4) in the presence of P2-tBu phosphazene base. Esterification of the hydroxyl groups of the OH-terminated PE star with 2,2-dichloroacetyl chloride led to (PE-Cl-2)(4) which was used as initiator (eight initiating atom transfer radical polymerization, ATRP, sites) for the synthesis of (PE-b-PMMA(2))(4) dendrimer-like stars by the ATRP of methyl methacrylate (MMA). All intermediates and final products were characterized by high temperature gel permeation chromatography and proton nuclear magnetic resonance spectroscopy.