Impregnation, dehydration and crosslinking of responsive organoboron polymer to generate smart gating membrane for multimolecular gradient separation

Abstract

Responsive materials have garnered increasing attention in the membrane separation field. However, fabricating smart gating membranes with tunable pore sizes to separate complex systems remains challenging. Herein, gating membranes with boroxine skeleton and temperature-tunable pores were successfully fabricated by fixing lower critical solution temperature (LCST)-type organoboron polymers (poly(N-isopropylacrylamide-co-glycidyl methacrylate/3-aminophenylboronic acid), PNG-APBA) onto the membrane surface via "impregnation-dehydration-crosslinking" strategy. The conformational behavior of the NIPAM-containing polymer chains (shrinking above LCST-stretching below LCST) serves as a functional gate, enabling the membranes to achieve reversibly tunable pore sizes and surface properties. The modified membranes exhibit gradient separation capabilities for small/medium/large molecules in complex polymer systems through temperature-tunable channels. The tunable pores also provided a potential tool for the high-selectivity separation of mixed proteins, such as lysozyme (LZM) and hemoglobin (Hb). Notably, the conformational behavior of the polymer chains endowed the membranes with excellent self-cleaning ability (FRR> 99.5 %), while the boroxine network enhanced the grafting stability of the polymer chains, ensuring effective reversibility and repeatability of membranes.