Preparation and properties of poly (vinylidene fluoride) membrane with inverse opal-like structure

Uniform pore size, high porosity and high flux are crucial to the application of membranes in separation. In this work, inspired by the special architecture of inverse opals (IOs)-a typical structure of photonic crystals (PCs), poly (vinylidene fluoride) (PVDF) membrane with uniform pore sizes, high porosity and high flux was fabricated by endowing the membrane with an IO-like structure, through sacrificing the template of SiO2 microspheres with HF. The sphericity and monodispersity of SiO2 microspheres were observed, the effects of HF on SiO2 micro -spheres and PVDF were studied, the membrane formation mechanism was investigated, and the membrane properties were discussed in detail. The results showed that during the membrane formation, SiO2 microspheres assembled from a disorder status into a relative ordered structure as PVDF polymer solidified, forming a rela-tively well-organized PVDF/SiO2 photonic crystals. Subsequently, the IO-like PVDF membranes were achieved after etching SiO2. The porosity and the pure water flux of the membrane could reach up to 76.77 % and 1145.92 L m -2h- 1 respectively. The pore size of the membrane was uniform, thus exhibiting outstanding rejection of silica microspheres (almost 100 %) and excellent anti-fouling properties, which indicated IO-like PVDF membranes had great applications in separation. This study revealed a novel and facile method to modulate PVDF mem-branes into a uniform, highly porous and permeable microstructure.

Automated summary

This study fabricated poly (vinylidene fluoride) (PVDF) membranes with uniform pore sizes, high porosity and high flux using an inverse opals (IOs)-like structure. The formation mechanism of the membranes was investigated, and their properties were discussed. The results showed that the membrane had excellent separation performance and anti-fouling properties. This study provided a novel approach for modulating the structure of PVDF membranes.