Surface modification of polypropylene microfiltration membranes by the immobilization of poly(N-vinyl-2-pyrrolidone): a facile plasma approach

This paper describes a facile approach for the surface modification of polypropylene microfiltration membrane (PPMM) by poly(N-vinyl-2-pyrrolidone) (PNVP), which involved the physical adsorption of PNVP, followed by a plasma treatment to immobilize PNVP on the membrane surface. Chemical and morphological changes of the membrane surface were characterized in detail by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and water contact angles measurements. Results reveal that both the plasma treatment time and the adsorbed PNVP amount have remarkable effects on the immobilization degree of PNVP. Pure water contact angle on the membrane surface decreases with the increase of PNVP immobilization degree, which indicates an enhanced hydrophilicity for the modified membranes. Static platelets adhesion experiment on the membrane surface was conducted to characterize the hemocompatibility of the PNVP-modified PPMM. The statistical amounts of adhered platelets on unit membrane area decrease significantly, which to a certain degree demonstrates that the hemocompatibility of the PNVP-modified membrane has been improved. Finally, permeation fluxes of pure water and bovine serum albumin solution were measured to evaluate the antifouling property of the PNVP-modified membranes, the results of which have shown an enhancement of antifouling property for the PPMMs. In a word, this pre-adsorption-plasma approach was found to be facile and useful in improving the hemocompatibility and the antifouling property of the PPMMs.