Preparation of a polyphenylene sulfide membrane from a ternary polymer/solvent/non-solvent system by thermally induced phase separation

Abstract

Polyphenylene sulfide (PPS) membranes were prepared via a thermally induced phase separation (TIPS) method. Diphenyl ketone (DPK) was selected as a diluent and dibutyl sebacate (DBS) was used as an auxiliary diluent. As the weight ratio of DBS to DPK increased from 10/66 to 17/59, the cloud point temperature of PPS/DBS/DPK increased from 250 to 263.5°C, crystallization temperature decreased from 225.4 to 219.2 °C and the interaction parameter between PPS and diluents changed from 1.57 to 1.91, which provided more opportunity for the casting solution to form the desired PPS membrane structure. When DBS concentration reached 16 wt%, an interesting sandwich-like PPS membrane structure with branch-like, bi-continuous, cellular structure was obtained, and the resulting membranes possessed the highest porosity, supreme water permeation and best mechanical properties. As DBS content increased, tensile strength improved from 0.55 to 4.22 MPa, and breaking elongation increased from 3.69 to 9.67%, but the mechanical properties of membranes with bi-continuous and cellular structure were much better than those of membranes with a spherical particle structure. Bovine serum albumin (BSA) was used as model foulant to investigate dynamic anti-fouling properties of membranes, and the effects of PPS concentration, cooling rate and coagulation bath styles on membrane structure were investigated. In addition, the PPS membrane had better performance against strong acid, strong alkaline and organic solvents than any other common membranes, and it showed extraordinary thermal stability.