Thermoresponsive membrane based on UCST-type organoboron polymer for smart gating and self-cleaning.

Thermoresponsive polymers can endow membranes with tunable separation and self-cleaning performance. However, up to now, there have been only very limited choices of thermoresponsive polymers for the fabrication of smart membranes. Herein, thermoresponsive membranes based on UCST-type organoboron polymer (Poly(CPBA)) were fabricated for the first time. Poly(CPBA) synthesized via a nucleophilic ring-opening reaction with Poly(GMA) and 3-carboxyphenylboronic acid has shown typical thermoresponsive behavior in water and water/ethanol mixture. Under vacuum conditions, Poly(CPBA) formed the cross-linked boroxine network on the membrane surface via a dehydration-induced condensation reaction. The reversible conformational change of Poly(CPBA) near UCST acted as a smart "gating" to regulate both pore size and surface properties of the membrane. When the temperature exceeded UCST, the fully extended polymer chains provided a strong washing force to remove contaminants, resulting in effective self-cleaning performance (FRR up to 99.2 %). In particular, due to the presence of the boroxine network, the polymer chains were firmly "stuck" on the membrane surface, providing stable performance and superior repeatability of the composite membrane. Illustration of thermoresponsive PAN/Poly(CPBA)/x membranes fabrication and the mechanism of self-cleaning and smart gating. [Display omitted] • Thermoresponsive membranes based on UCST-type organoboron polymers were fabricated via simple surface impregnation. • Membrane thermoresponsive as a smart gating modulation of pore size and surface properties. • The boroxine network endows membranes with excellent stability and repeatability. • Membranes exhibit tunable separation and efficient self-cleaning performance. [ABSTRACT FROM AUTHOR]