Unusual quantitative (co)polymer chain coupling reaction based on isoprene and cobalt complexes

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)-bpoly(vinyl acetate) triblock copolymers and their derivatives.