Novel thermo-sensitive membranes prepared by rapid bulk photo-grafting polymerization of N,N-diethylacrylamide onto the microfiltration membranes Nylon

Novel thermo-sensitive membranes were prepared by photo-grafting N,N-diethylacrylamide (DEAAm) onto the microfiltration membranes of Nylon with benzophenone (BP) as an initiator. Grafted membranes with a wide range of grafting yield were obtained through varying the grafting conditions, including UV intensity, the irradiation time and the mole ratio of initiator. The existence of the grafted layers of poly(N,N-diethylacrylamide) (PDEAAm) was confirmed by ATR-FTIR and XPS measurements. The SEM images indicated that the grafted polymers existed mainly on the top surface and inside the pores rather than on the backside. The water flow rate of the membranes with the appropriate grafting yield increased sharply with increasing temperature to the range of 30-35 °C near the lower critical solution temperature (LCST), which revealed the performance of the thermo-sensitivity after grafting modification. The influence of grafting yield on the filtration property of the membranes was also investigated. The grafted PDEAAm chains existed on the expanded configuration and extended out of the surface of the membranes when dried below the LCST while shrunk to the membrane surface above the LCST, which was measured by AFM.