In Situ Crosslinking of Hyperbranched Polyglycerol in Casting Solutions and Its Effect on the Structure and Properties of Porous PVDF Membranes

摘要

Porous membranes were prepared via phase inversion process from casting solutions composed of poly(vinylidene fluoride), hyperbranched polyglycerol (HPG), and N,N-dimethylacetamide. To seek a stable presence of HPG in the resulting membranes, it was crosslinked in the casting solutions using 4,4'-oxydiphthalic anhydride as the crosslinking agent. The membranes were characterized in terms of morphology, surface and bulk chemical compositions, water contact angle, porosity, water flux, and bovine serum albumin (BSA) adsorption experiments. The effects of HPG content and crosslinking degree on the membrane structure and properties were investigated. The increasing of crosslinking degree resulted in a significant improvement in HPG stability in the membrane matrix, and a remarkable enrichment of the crosslinked HPG at the separation surface was observed when the membrane was shaken in water at a relatively high temperature (60 degrees C). This enrichment led to a decrease in the value of water contact angle and an improvement in fouling-resistance. To optimize the membrane performance, a small amount of poly(vinylpyrrolidone) (PVP) was used as an additive, and it was found that the addition of PVP led to a considerable increase in water flux.