Synthesis of novel block copolymers by cobalt-mediated radical polymerization (CMRP) and isoprene-assisted radical coupling reaction (I-ARC)

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and well-defined molecular parameters. In this context, we designed an innovative and very promising tool for macromolecular engineering. This technique, called Isoprene-Assisted Radical Coupling (I-ARC), allows to couple quantitatively polymer chains preformed by Cobalt-Mediated Radical Polymerization (CMRP), an efficient controlled radical polymerization system for vinyl acetate (VAc) and acrylonitrile (AN). Typically, addition of isoprene to well-defined polymers prepared by CMRP invariably leads to the quantitative coupling reaction of the chains, as assessed by the perfect doubling of the molar mass of the polymer. Importantly, the I-ARC reaction is not limited to macromolecules with low molar masses and homopolymers, contrary to the previously reported radical chains coupling methods. Indeed, when applied to diblock copolymers, I-ARC constitutes a straightforward approach for the synthesis of telechelic symmetrical ABA triblock copolymers, as illustrated by the preparation of poly(vinyl acetate)-b-poly(acrylonitrile)-b-poly(vinyl acetate) triblock copolymers and their derivatives.