Effect of doping porous ZrO2 solid superacid shell/void/TiO2 core nanoparticles (ZVT) on properties of polyvinylidene fluoride (PVDF) membranes

• ZVT are successfully prepared.
• ZVT were dopped into PVDF to prepare ZVT/PVDF composite membranes.
• Micro reaction locations (MRLs) are formed inside PVDF membranes.
• ZVT can interact with PVDF chains by hydrogen bonds.

In this paper, porous ZrO2 solid superacid shell/void/TiO2 core nanoparticles (ZVT) were firstly prepared and then doped them to polyvinylidene fluoride (PVDF) to prepare a novel composite membrane (ZVT/PVDF composite membrane) through a phase inversion process, enhancing the capabilities of anti-fouling, anti-compaction and hydrophilicity of PVDF membranes. ZVT were investigated through scanning electron microscope (SEM), transmission electron microscope (TEM) and Fourier transform infrared (FT-IR). The results indicate that ZVT with the diameter of around 500 nm are uniformly dispersed in PVDF membranes, the thickness of the ZrO2 shell are roughly 50 nm and the ZrO2 shell shows a porous structure, and a solid superacid ZrO2 shell on the TiO2 core is formed due to a stretching vibration peak of SO double bond at 1460 cm− 1 in FT-IR spectra; alternatively, ZrO2 solid superacid shell of ZVT with strong acidity can form hydrophilic surroundings on the surface of PVDF membranes, and abundant hydroxyl groups on the surface of ZVT interact with PVDF chains by hydrogen bonds; furthermore, micro reaction locations (MRL) existing inside channels and surface of PVDF membrane enhance its properties. Therefore, ZVT are desirable functional nanomaterials as fillers of PVDF membranes.