Thermostable antifouling zwitterionic vapor-induced phase separation membranes

Abstract

Biofouling resistance of membranes is generally evaluated in normal conditions of temperature. Yet, some membranes can undergo heat treatments either before use (sterilization for biomedical use) or during operation (when temperature gradient is the driving force to the separation), which can impair the anti-biofouling material. Here, we prepared zwitterionic polyvinylidene fluoride membranes by the vapor-induced phase separation (VIPS) process, using a copolymer made of styrene units and zwitterionized 4-vinylpyridine. Membranes were fully characterized by a variety of physicochemical analyses to demonstrate the formation of bi-continuous structure and the presence of the zwitterionic copolymer on the surface of the membrane. Then, anti-biofouling properties were studied at ambient temperature using Escherichia coli bacteria, whole blood, platelet rich plasma and bovine serum albumin, before moving onto their assessment at higher temperature (60 °C) or after a steam sterilization of the membranes. Results demonstrated that anti-biofouling properties were sustained despite the heat treatment, while some common zwitterionic anti-biofouling materials (sulfobetaine methacrylate) is known to fail in similar conditions. Hence, the present membranes can be applied in a large variety of domains where bi-continuous microfiltration anti-biofouling membranes are needed and undergo heat exposure or heat treatment.