Synthesis of novel oligoester-block-polyacrylate-block-oligoester ABA triblock copolymers by coupling methods

Abstract

An original approach based on coupling methodology was used to prepare novel well-defined ABA triblock copolymers, made of polyester-type chain ends (A) associated with a polyacrylate midblock (B). Poly(ethylene terephthalate)-block-poly(lauryl acrylate)-block-poly(ethylene terephthalate) (PET-b-PLAc-b-PET) copolymers were achieved from poly(ethylene terephthalate)-b-poly(lauryl acrylate) (PET-b-PLAc) diblock ones. The first step consisted in the synthesis of diblock copolymers by atom transfer radical polymerization of lauryl acrylate starting from PET segment as a macroinitiator. In the second step, the coupling of diblock copolymers was achieved using four different methods, which were evaluated and compared: atom transfer radical coupling, “click” chemistry using the Huisgen's reaction, and coupling via a dithiol reagent or a diisocyanate molecule. Coupling using the Huisgen's reaction or a diisocyanate spacer proved to be the most efficient techniques. Even if these methods showed limitation and were only adapted for copolymers with low molecular weights, we managed to successfully prepare ABA triblock copolymers involving a polyester segment as end blocks and a polyacrylate moiety as midblock. To our knowledge, such kind of chemical structure has never been reported before and would be useful, possibly affording physical networks leading to rheological modification, for instance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012