Tailoring poly(vinylbenzocyclobutene)-b-poly(4-vinylpyridine) isoporous block copolymer membranes: functionalization and performance optimization

Abstract

Amphiphilic block copolymers are promising candidates for the fabrication of ultrafiltration membranes with an isoporous integral asymmetric structure. Within this study we demonstrate the synthesis and membrane fabrication of the new block copolymer (BCP) poly(vinylbenzocyclobutene)-b-poly(4-vinylpyridine) (PVBCB-b-P4VP). The membranes were fabricated using a self-assembly non-solvent induced phase separation process (SNIPS) resulting in an isoporous integral asymmetric structure comprising a unique foam-like substructure with a homogenous three-dimensional porosity throughout the whole membrane body. The dependence of the membrane formation process on the evaporation time, the polymer concentration of the initial casting solution and the molecular weight as well as the block copolymer composition was investigated. Furthermore, the pore diameters of the BCP membranes were tailor-made by simply adjusting the molecular weight of the pore forming P4VP block segments. Moreover, the BCP membranes were functionalized with octylbromide resulting in quaternized P4VP block segments and consequently in positively charged pores. Finally, water flux and retention measurements with proteins of the pristine and functionalized membranes were demonstrated.