Porous Cellulose Acetate by Specific Solvents with Water Pressure Treatment for Applications to Separator and Membranes

In this study, straight nanoporous cellulose acetate (CA) membranes were fabricated by utilizing N -methyl pyrrolidinone (NMP) and acetone with water pressure, without the use of inorganic additives. The nanoporous CA polymer was fabricated as a result of the difference in vapor pressure between NMP and acetone. As the vapor pressure of NMP is lower than that of acetone, NMP could be contained in the CA membrane by regulating the drying process. Furthermore, the incorporation of NMP incorporated into the CA membrane led to an increase in the plasticization effect via an increase in the free volume of the CA chains. Thus, the CA chains weakened by NMP were exposed by high water pressure, producing a porous region. The pore size and porosity could be easily controlled by both the NMP content and the water pressure in the CA polymer. It was confirmed that the pore size and porosity were controlled by water pressure because the water flux of the porous CA polymer gradually increased with an increase in water pressure. Moreover, the water flux increased with increasing NMP content in the CA polymer. The water flux of the CA polymer containing 1 wt% NMP was found to be 58.38 L/m 2 h at 8 bar. In contrast, the CA polymer with 2 wt% NMP exhibited an improved water flux of 155.50 L/m 2 h at 8 bar.