Modification And Characterization Of Zwitterionic Polymers On Polysulfone Membrane

Due to its good mechanical properties, flexibility, oxidation resistance, thermal stability and biocompatibility, polysulfone(PSU) has been widely used in the field of microfiltration, ultrafiltration, dialysis, and gas separation. However, most of polysulfone material is relatively hydrophobic, which leading to the fouling of membrane. To improve its hydrophilic properties and anti-pollution, this dissertation focuses on the surface modification of PSU membrane via grafting hydrophilic zwitterionic polymers to polysulfone membrane material. The whole paper consists of two sections:Section I, Zwitterionic sulfobetaine groups were grafted onto polysulfone(PSU) membrane surface with 2-azidoethyl methacrylate and N,N-diethyl-N-propargyl-N-(3-sulfopropyl) ammonium(DEPAS) via surface-initiated Atom Transfer Radical Polymerization(ATRP) and “click” chemistry in a two-step process. The PSU membranes were fully characterized by attenuated total reflectance Fourier transform infrared spectra(ATR-FTIR), X-ray photoelectron spectroscopy(XPS), static water contact angle(WCA) measurement,adsorption of Bovine Serum Albumin and antibacterial properties(Escherichia coli and Staphylococcus aureus). Results showed that zwitterionic monomers were efficiently grafted onto PSU surfaces. The water contact angle, bovine serum albumin(BSA) protein adsorption and platelet adhesion were obviously decreased after grafting zwitterionic sulfobetaine groups onto the membrane surface. These indicated that the zwitterionic sulfobetaine modified PSU membranes presented good biocompatibility. This study provides a new approach for surface modification of polysulfone with different functionalities.Section II, Zwitterionic polymer brushes based on cysteine methacrylate(CysMA) were successfully grafted to polysulfone substrates by surface-initiated atomic-transfer radical polymerization(SI-ATRP), and exhibited excellent anti-fouling activities. Various characterization techniques, including attenuated total reflectance Fourier transform infrared spectra(ATR-FTIR), atomic force microscopy(AFM), and X-ray photoelectron spectroscopy(XPS) were used to characterize the polymer brush-modified polysulfone membrane. Subsequently the hydrophilicity, anti-biofouling and antibacterial properties(Escherichia coli) activities of the polymer brush substrates were evaluated. The experimental results showed that the pCysMA shows better hydrophilicity and effectively resisted the adsorption of bovine serum albumin(BSA) protein.