Nanostructured switchable pH-responsive membranes prepared via spherical polyelectrolyte brushes

A nano-porous and switchable pH-responsive polymeric membrane was fabricated through filtration technique with the assist of metal hydroxide nanostrands as template. A common used spherical polyelectrolyte brush (SPB), PAA@PS (poly (acrylic acid)) brushes grafted on polystyrene nanospheres, employed in this work as polymeric membrane. It features tunable pore size on line by shrinkage or stretching of PAA brushes under different pH value or ionic strength. Furthermore, both the length of PAA chains and the dimension of PS cores could tailor the pore size of the membrane effectively. These properties of PAA@PS membrane could separate nanoparticles within 10 nm with precise size-selective permeation. Meanwhile, since the membrane was endowed negative charge by PAA brushes, the membrane could adsorb and separate positive charge nanoparticles including dyes though the mixture solution effectively. Herein, this stimuli-responsive membrane is promising in the separation of ultrafine nanoparticles with precise size and charge selectivity.