Preparation and characterization of surface modified electrospun membranes for higher filtration flux

Abstract

Popular polymers such as polysulfone and poly(vinylidene fluoride) (PVDF) when electrospun into a membrane, have a much higher contact angle and hence are more hydrophobic when compared to the virgin polymeric material. In direct liquid penetration it is more beneficial if the membrane is hydrophilic so that the flux is not compromised and has less tendency to foul. Hence, this research is focused on generating a highly hydrophilic electrospun membrane (EM) based on PVDF material by blending this polymer with several different types of surface modifying macromolecules (SMMs) prepared from urethane pre-polymer with poly(ethylene glycol)s (PEGs) of various average molecular weights (400, 600, and 1000 Da) and poly(propylene glycol) of average molecular weights 3500 and 425 Da. One of the SMMs, with PEG 1000 Da, had a significant impact on the hydrophilic nature (0° SCA with water) of the EM as compared to the blend casted membrane. This could possibly be due to the orientation of the SMMs hydrophilic groups adopted during electrospinning on the surface, whereas they are either encapsulated or submerged in other SMMs. The water flux at a given pressure of blended EM was higher than the non-blended electrospun PVDF membrane. This study highlights the potential benefits of this new hydrophilic polymeric material in the membrane field, which can achieve high-flux rates at low pressure.