A novel process for membrane fabrication: thermally assisted evaporative phase separation (TAEPS)

Poly(vinylidene fluoride) (PVDF) membranes fabricated from conventional processes have a limited range of microstructures. For example, PVDF membranes with spherulitic and isotropic microstructures containing macrovoids are extremely difficult to avoid using standard casting techniques such as wet-casting and thermally induced phase-separation (TIPS) casting. In order to create novel PVDF membrane microstructures such as a spongy, open-celled structure, a new membrane-formation process with six independent process parameters has been developed. Because this new process, thermally assisted evaporative phase separation (TAEPS), has a large number of parameters, the membrane microstructures are easily changed. The TAEPS process can fabricate a PVDF membrane with a spongy, anisotropic microstructure without macrovoids using a simple ternary system with no additives. In addition to studying the novel and unique microstructures available with the TAEPS process, the relationship between final morphology, performance, and processing conditions has been investigated in this paper.