New polymethylene-b-poly(styrene-co-2-hydroxyethyl methacrylate) and polymethylene-b-poly(styrene-co-2-hydroxyethyl methacrylate)-g-poly(ε-caprolactone)) copolymers: Synthesis, characterization and their application in the fabrication of highly ordered porous films

Abstract

A series of new polymethylene-b-poly(styrene-co-2-hydroxyethyl methacrylate) (PM-b-P(St-co-HEMA)) and polymethylene-b-poly(styrene-co-2-hydroxyethyl methacrylate-g-poly(ε-caprolactone)) (PM-b-P(St-co-HEMA-g-PCL)) copolymers were successfully synthesized via a strategy combined polyhomologation of ylides, reversible addition–fragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP). Firstly, a hydroxyl terminated polymethylene (PM-OH) was obtained via polyhomologation of ylides followed by oxidation. Then, PM-OH was transformed to a macromolecular chain transfer agent (PM-CTA). Subsequently, RAFT copolymerizations of styrene (St) and 2-hydroxyethyl methacrylate (HEMA) were performed using PM-CTA as chain transfer agent, targeting the well-defined PM-b-P(St-co-HEMA) copolymers with controllable molecular weight and narrow molecular weight distribution. Finally, the ring-opening polymerization of ε-caprolactone was carried out using PM-b-P(St-co-HEMA) copolymer as initiator to achieve PM-b-P(St-co-HEMA-g-PCL) copolymer. The molecular weight and chain structure of the obtained copolymers were characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance (1H NMR) and Fourier Transform Infrared spectroscopy (FTIR). Moreover, the fabrication of highly ordered porous films using the amphiphilic PM-b-P(St-co-HEMA) copolymers via a static breath-figure process was investigated.