Morphological study of poly(vinylidene fluoride) asymmetric membranes: Effects of the solvent, additive, and dope temperature

Asymmetric poly(vinylidene fluoride) (PVDF) membranes were cast with commercial-grade Kynar K760 polymer pellets and four different solvent systems: N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, 1-methyl-2-pyrrolidone, and triethyl phosphate. With a focus on the PVDF/DMAc system, the effects of various additives (i.e., ethanol, glycerol, lithium chloride, lithium perchlorate, and water) on the resulting membrane morphology were investigated. The membrane morphology was examined with scanning electron microscopy. The effect of the dope solution temperature on the membrane morphology was also studied for the various additives used. (C) 2004 Wiley Periodicals, Inc.