Novel tri-block copolymers of poly(acrylic acid)-b-poly(2,2,3,3,4,4,4-hexafluorobutyl acrylate)-b-poly(acrylic acid) prepared via two-step RAFT emulsion polymerization

A facile method for preparing ABA tri-block functional elastomers via two-step RAFT emulsion polymerization is introduced in this work. Poly(acrylic acid)-b-poly(2,2,3,3,4,4,4-hexafluorobutyl acrylate)-b-poly(acrylic acid) (PAA-b-PHFBA-b-PAA) tri-block copolymers were synthesised, and transparent films were obtained by directly casting the synthesized latexes. The water contact angle (WCA) of the as-prepared films was dramatically improved after heat treatment at 120 °C for 4 h, and the films were changed from hydrophilic to hydrophobic. By using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), the surface structure of the films was investigated in this work, to illustrate the mechanism of the variation in the surface properties of the films upon heat treatment. Moreover, the synthesized tri-block copolymers behave as elastomeric materials, with a high elongation at break of around 1200% and a permanent deformation of below 25%.