Towards high-performance hybrid hydrophilic membranes: chemical anchoring of hydroxyl-rich nanoparticles on PVDF membranes via a silane coupling agent

Physical blending with hydrophilic nanoparticles (NPs) is generally adopted to improve the performance of hydrophobic membranes. Stable immobilization of the NPs remains challenging due to the weak bonding. Covalent bonding is expected to overcome this problem. Herein, γ-methacryloxy propyl trimethoxy silane (MPTS) was grafted onto PVDF membranes, affording a versatile materials platform to firmly anchor hydroxyl-rich nanomaterials (HRNs) (TiO₂, SiO₂, β-FeOOH-1, β-FeOOH-2, etc.) via a facile dehydration process. The stability of the resulting hybrid PVDF-g-PMPTS/HRN membranes is remarkably improved, as evidenced by their almost unchanged water contact angles even under ultrasonication for 30 min. The immobilization yield of HRNs, hydrophilicity, roughness and water flux of the membranes are enhanced with increasing graft degree of PMPTS. The resulting hybrid membranes exhibit much better water flux recovery ratio and BSA rejection ratio compared to the pristine PVDF membrane, owing to their excellent anchoring stability and outstanding hydrophilicity. This work provides a general effective chemical route to the construction of hybrid hydrophilic membranes with high performance.