Synthesis of block copolymers by combination of an activated monomer and free radical polymerization mechanism

Abstract

ABSTRACT: Epichlorohydrin (ECH) was polymerized by an activated monomer mechanism (AM) in the presence of 4,4’-azobis(4-~yanopentanol). Spectroscopic mid degradation studies showed that polymers obtained via this initiation method contained an azo linkage in the main chain. These prepolymers were employed in the polymerization of styrene (St) to yield block copolymers. Introduction Block copolymers have recently been a subject of interest mainly from the practical viewpoint of material science. Block copolymers may exhibit diverse mechanical prop- erties which are not shown by homopolymers. Synthesis of block copolymers having different combinations of components and molecular weight distributions has been a subject of interest for many years. Classical methods using a single type of propagating species such as anionic polymerization are limited to certain types of monomers and exclude monomers that polymerize by other mech- anisms. The transformation approach in block copolymer synthesis, in which different propagating species are used, allows multiple combinations of monomers.1s2 In our preceding papers, we used the transformation approach to demonstrate the possibility of producing block copol- ymers by combinations of free radical polymerization with anionic insertion? cationi~,~ promoted cationic?