Preparation of Polyvinylidene Fluoride (PVDF) Membranes via Nonsolvent Induced Phase Separation Process using a Tween 80 and H₂O Mixture As an Additive

Abstract

Polyvinylidene fluoride (PVDF) membranes were fabricated by the nonsolvent induced phase separation (NIPS) process using Tween 80 and H2O as a mixture additive from both 60 °C and room-temperature (RT) casting solution. Resultant PVDF membranes revealed improved pure water flux (PWF), enlarged mechanical properties, and well Bovine serum albumin (BSA) and Dextran rejection as a result of addition of water into the PVDF–DMAc–Tween 80 system. The improved performance was attributed to the existence of nonsolvent, which was solubilized by polar head groups of Tween 80 reverse micelle to form the water pool. Further, the interaction between polar head of surfactant and water provided a balance resistance to the interconnection between PVDF and hydrophobic chains of surfactant, which enhanced the thermodynamics stability of casting solution. During demixing process, water diffusion from the interior of casting solution, increased the precipitation rate and led to the insufficient crystallization process of polymer. Finally, the Tween 80 reverse micelle confined the movement of water in solution, making the fingerlike structure slim and confined, with the wall structure between macrovoids.