Explorations of complex thermally induced phase separation (C-TIPS) method for manufacturing novel diphenyl ether polysulfate flat microporous membranes

A complex thermally induced phase separation (C-TIPS) method combining the advantages of non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS) was proposed to prepare novel diphenyl ether polysulfate (De-PSE) flat membranes, using a good solvent Dimethyl acetamide (DMAC) and a neutral solvent Triethyl phosphate (TEP) as mixed solvents and a non-solvent Polyethylene glycol (PEG-400) as additive. The competition between NIPS and TIPS processes was regulated by adjusting the composition and temperature of quenching bath, so as to achieve fine tuning of membrane surface pore size, morphology, as well as permeability and mechanical property. The membrane cross section exhibited the coexistence of bi-continuous and finger-like pore structures. Compared with membranes prepared by the mainstream NIPS method, the pure water flux improved from 187.62 to 945.27 L m −2 h −1 ·bar −1 with a mean pore size increased from 30 nm to 195 nm, while the tensile strength enhanced from 2.31 to 5.89 MPa. This work demonstrated a simple strategy to improve the comprehensive performances of De-PSE membranes. Coupled with the strong acid-alkali resistance of the membrane, it greatly expanded the membrane application prospect, especially in the treatment of high polymer textile and papermaking wastewater with large volumes and strong alkalinity. • Novel De-PSE flat membranes were prepared by C-TIPS method. • Tuned membrane surface pore size by adjusting quenching bath conditions. • The mechanical strength is significantly improved. • Membrane morphology exhibit finger-like and bi-continuous coexistence structure. • The membrane pore size distribution is more uniform.