Synthesis and self-assembly of polystyrene-based diblock and triblock coil–brush copolymers

Abstract

Synthesis of coil–brush, brush–coil–brush and coil–brush–coil polystyrene-based di- and tri-block copolymers containing poly(acrylic acid) (PAA) side chains via RAFT polymerization is reported demonstrating the effect of RAFT CTA on kinetics and the structure of the resulting polymers. Several mono- and bi-functional RAFT CTAs were used which enabled the synthesis of target copolymers with a relatively low dispersity index and the desired DP of PAA side chains. Polystyrene-based anionic brush copolymers were studied by SEC with triple detection, ¹H NMR spectroscopy, TEM, DLS, and water contact angle measurements. According to the wettability of the copolymer films, the most hydrophilic copolymers were of coil–brush and brush–coil–brush structures, especially with longer PAA chains. Polystyrene-based anionic brush copolymers in mixed solutions of DO and water formed micelles and, at a larger amount of water, micellar aggregates with a hydrodynamic diameter of 500–1000 nm. The shape and size of the micelles were dependent on the location of brush and linear blocks; the formation of micellar aggregates was more prevalent for the brush copolymers with short PAA side chains. This study provides an efficient approach for the preparation of polystyrene-based brush copolymers of various structures whose properties could be tuned by the use of different RAFT CTAs.