Poly(vinylidene fluoride) (PVDF) hollow-fiber membranes were prepared from a Tween 20/water/triethyl phosphate/PVDF system. The effects of Tween 20 on the morphology and properties of the membranes were explored. Field emission scanning electron microscopy imaging indicated the presence of skinlike layers on both surfaces of the membranes. In the cross section, a bicontinuous morphology comprised of interlocked crystallites was observed. As the dosage of Tween 20 was raised, the size and quantity of nanopores on the surfaces increased, and the morphology of the crystallites in the cross section changed from sheaflike to sticklike. Tween 20 was removed almost completely during the membrane-formation process, as validated by Fourier transform infrared–attenuated total reflection and 1H-NMR spectrometry. Dextran filtrations were preformed to demonstrate the potential applications of these membranes in separation processes.
