Preparation of a new PVDF membrane with inverse opal structure for high-precision separation

Abstract

Inspired by natural isoporous materials and the highly arranged structure of photonic crystals (PCs), an inverse opal (IO)-structured membrane with a highly interconnected through-hole structure, a high porosity, and a nearly uniform pore size was prepared by multiosmosis method. Silica (SiO2) microspheres were assembled as building blocks into opal crystals, and poly (vinylidene fluoride) (PVDF) acted as the frame material of the membrane. The influencing factors in the fabrication of high-quality opal PCs were studied. Binary PVDF/SiO2 composite PCs were obtained by multiosmosis of a PVDF solution, and the infiltration mechanism was investigated, which indicated that the PVDF polymers were uniformly cured throughout the crystal area to form SiO2/air/PVDF composite PCs until completely infiltrated. Then, the IO-structured membrane was achieved after etching SiO2 microspheres. Different particle sizes of SiO2 microspheres were used to prepare PVDF membranes with various pore sizes. The pure water flux and porosity could reach as high as 5208.71 L m−2h−1 and 83.59%, respectively. The membranes displayed excellent rejection of SiO2 microspheres, almost 100%, and great antifouling performance. This work provided a simple and efficient method for constructing a filtration membrane with IO structure, which hopefully would solve the problems encountered in realizing efficient, high-precision separation.