Improved separation and antifouling properties of PVDF gravity-driven membranes by blending with amphiphilic multi-arms polymer PPG-Si-PEG

Abstract

Fabricating high-flux, low-fouling gravity-driven membranes (GDM) has proved to be an extremely challenging work. In this study, a novel tailored amphiphilic multi-arms polymer poly(propylene glycol)-silane-poly(ethylene glycol) (PPG-Si-PEG) was synthesized and blended into Polyvinylidene Fluoride (PVDF) matrix to fabricate GDM via nonsolvent induced phase separation method. The incorporation of multi-arms polymers affected phase separation and surface segregation behaviors, resulting in the formation of more porous structure, which were demonstrated by scanning electron microscopy (SEM). Moreover, the hydrophilic PEG arms in polymers were enriched onto membrane surface through surface segregation and utilized to improve the hydrophilicity of membranes, which were confirmed by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle measurement. The separation and antifouling properties of the membranes were evaluated by using gravity as the driving force, employing bovine serum albumin (BSA) as the model foulant. The water flux of membranes increased from 4.6 L m−2 h−1 for the control membrane to 12.1 L m−2 h−1 for PVDF/PPG-Si-PEG∼5% membrane. The antifouling properties of modified membranes were effectively improved in comparison with that of control membrane. The flux recovery ratio, especially for PVDF/PPG-Si-PEG∼5% membrane, was up to 99.4%. This study provided a new method for antifouling modification of GDM.