Fabrication of PVDF hollow fiber membranes: Effects of low-concentration Pluronic and spinning conditions

Due to the unique properties of amphiphilic Pluronic block copolymers, they have been blended with other polymers such as PVDF to prepare membranes. Considering the stability issue, the strong pore-forming ability of Pluronic F127, and the mechanical strength of the resultant membranes, Pluronic/LiCl mixed additive consisting of a very low concentration of Pluronic has been used in this study. The effects of spinning conditions on PVDF hollow fiber fabrication have also been studied. It is found that the use of merely 0.2 wt% of Pluronic is sufficient to impose significant impacts on the morphology, filtration performance, and mechanical properties of the resultant fibers. Hollow fibers spun using higher coagulant temperature, higher take-up speed, and water as the bore fluid exhibit better mechanical properties and filtration performance. PVDF hollow fiber membranes with PWP of 1180 L/m2 h MPa and MWCO of 5 kDa were obtained when spun with optimized spinning conditions and using 3 wt% of LiCl and 0.2 wt% of Pluronic as the mixed additive. The fibers can withstand a pressure of 0.55 MPa from the lumen.