Synthesis of highly porous poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) asymmetric membranes

YH Xie and N Moreno and VM Calo and H Cheng and PY Hong and R Sougrat and AR Behzad and R Tayouo and SP Nunes, POLYMER CHEMISTRY, 7, 3076-3089 (2016).

DOI: 10.1039/c6py00215c

For the first time, self-assembly and non-solvent induced phase separation was applied to polysulfone-based linear block copolymers, reaching mechanical stability much higher than other block copolymer membranes used in this method, which were mainly based on polystyrene blocks. Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) (PtBA(30k)-b-PSU14k-b-PtBA(30k)) with a low polydispersity of 1.4 was synthesized by combining step-growth condensation and RAFT polymerization. Various advanced electron microscopies revealed that PtBA(30k)-b-PSU14k-b-PtBA(30k) assembles into worm-like cylindrical micelles in DMAc and adopts a "flower-like" arrangement with the PSU central block forming the shell. Computational modeling described the mechanism of micelle formation and morphological transition. Asymmetric nanostructured membranes were obtained with a highly porous interconnected skin layer and a sublayer with finger-like macrovoids. Ultrafiltration tests confirmed a water permeance of 555 L m(-2) h(-1) bar(-1) with a molecular weight cut-off of 28 kg mol(-1). PtBA segments on the membrane surface were then hydrolyzed and complexed with metals, leading to cross-linking and enhancement of antibacterial capability.

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