Preparation of PU modified PVDF antifouling membrane and its hydrophilic performance

A simple and convenient method for the preparation of hydrophilic polyurethane (PU) modified poly(vinylidene fluoride) (PVDF) membranes was developed. First, PU with hydroxyl functional end-groups was synthesized in one-step from polyethylene glycol 400(PEG 400) and isophorone diisocyanate (IPDI), and the raw product was directly added into casting solution without further purification to modify the PVDF membrane. The properties and performance of the prepared PU/PVDF membranes were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), contact angle measurement, protein adsorption and filtration test. FTIR and XPS analyses indicate that PU with hydroxyl functional end-groups was successfully incorporated and enriched onto the membrane surface, while filtration test and SEM analysis show that more and larger pores were formed on the blended membranes, which significantly improves the permeation performance of the modified membranes, compared with the unmodified PVDF membrane. Results from protein adsorption and flux recovery experiment reveal that hydrophilic PU modification substantially improves the fouling resistant ability of the modified membranes. In addition, the effects of the molar ratio of PEG 400 to IPDI and the content of the PU additive on the properties and performance of the PU/PVDF membranes were also investigated.