Precision-aiming tuning of membranes prepared by NIPS and its performance enhancement

An industrially developed non-solvent induced phase separation (NIPS) for porous membranes is still being studied to improve performances and expand application fields. The work introduces a novel strategy to tune the structures of porous membranes via the combination of glass transition temperatures (Tg) and external stimulations. Tg was adjusted by the content of residual solvents and additives. Heat and air blowing for higher Tg porous membranes than 100 °C were efficient strategies to improve the surface porosity to 65%, the water flux to 600 LMH/bar, and the BSA rejection to 99.8%. Heat and vacuum for lower Tg membranes than 100 °C could melt the surface pores and becomes a pier-like structure with the water flux of 2.4 LMH/bar and Na2SO4 rejection of 95.6%. The method could hold great potential for achievable tuning of main characteristic parameters such as structure, performance, porosity, pore size, and molecular weight cut-off.