Preparation of polysulfone-based block copolymer ultrafiltration membranes by selective swelling and sacrificing nanofillers

Selective swelling of block copolymers of polysulfone-b-poly(ethylene glycol)is an emerging strategy to prepare new types of polysulfone ultrafiltration membranes.Herein,we prepared nanoporous polysulfoneb-poly(ethylene glycol)ultrafiltration membranes by selective swelling and further promoted their porosity and ultrafiltration performances by using CaCO_(3) nanoparticles as the sacrificial nanofillers.Different contents of CaCO_(3) nanoparticles were doped into the solution of polysulfone-b-poly(ethylene glycol),and thus obtained suspensions were used to prepare both self-supported and bi-layered composite structures.Selective swelling was performed on the obtained block copolymer structures in the solvent pair of ethanol/acetone,producing nanoporous membranes with poly(ethylene glycol)lined along pore walls.The CaCO_(3) nanoparticles dispersed in polysulfoneb-poly(ethylene glycol)were subsequently etched away by hydrochloric acid and the spaces initially occupied by CaCO_(3) provided extra pores to the block copolymer layers.The porosity of the membranes was increased with increasing CaCO_(3) content up to 41%,but further increase in the CaCO_(3) content led to partial collapse of the membrane.The sacrificial CaCO_(3) particles provided extra pores and enhanced the connectivity between adjacent pores.Consequently,the membranes prepared under optimized conditions exhibited up to 80%increase in water permeance with slight decrease in rejection compared to neat membranes without the use of sacrificial CaCO_(3) particles.