Block copolymers (BCPs) consist of two or more chemically distinct polymer chains joined together via a covalent bond. Due to the thermodynamic incompatibility between the polymer blocks, BCPs can self-assemble into various nanostructures such as spheres, cylinders, lamellae, and gyroids. In particular, porous materials based on cylindrical structures could be used in various applications including catalysts and filtration membranes, among others. However, preparation of porous materials involves multiple tedious steps for practical use including component removal. Therefore, a material that can form porous structures with less steps and lower costs is required. Recently, we found that the fluorine-containing BCP, poly(2,2,2-trifluoroethyl methacrylate)-block-poly(2-vinyl pyridine) (PTFEMA-b-P2VP) forms periodic porous nanostructures without needing any removal steps. In this study, to investigate the mechanism and functionality of the polymer contributing to pore formation, a series of block copolymers with different chemical compositions based on PTFEMA-b-P2VP was synthesized. First, to clarify the effect of hydrophilicity in P2VP on pore formation, polystyrene which shows hydrophobic properties relative to P2VP was used to synthesize PTFEMA-b-polystyrene (PTFEMA-b-PS). After that, to elucidate the contribution of fluorine moieties, poly(2,2-difluoroethyl methacrylate)-b-PS and poly(2-monofluoroethyl methacrylate)-b-PS were synthesized. These mono- and di-functionalized monomers were prepared by esterification with methacrylic acid. All the polymers were synthesized by RAFT polymerization. The results obtained from gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) suggested that all the polymers were successfully synthesized without significant side reactions. Through the characterizations in the bulk state by small-angle X-ray scattering (SAXS) and in the thin film by atomic force microscopy (AFM), the self-assembly behavior of the polymers were investigated.

Synthesis of fluorine-containing block copolymers for porous membrane preparation via RAFT

255th National Meeting (2018)

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