Antifouling Surfaces And Their Properties Based On Polysulfobetaine And Polyethylene Glycol

Polypropylene micofiltration membrane (PPMM) is a promising polymeric membrane, which has been widely used due to its excellent stability, high mechanical strenghth and low cost. However, the high hydrophobicity easily causes fouling, which is limits its widespread application. Polyethylene glycol (PEG) and poly(sulfobetaine methacrylate) (PolySBMA), which is a typical polyzwitterion, have been extensively investigated in the surface modification with good antifouling capability. In this work, three facile and effective modification methods are introduced to fabricate antifouling surfaces based on the excellent hydrophilicity of PSBMA and PEG. What’more, the oxidative stability of PSBMA and PEG were also compared and evaluated. Our specific studies are concentrated on the following aspects:Firstly, PSBMA was co-deposited with polydopamine (PDA) to decorate steel meshes. The effect of PSBMA concentration on the mesh surfaces was studied in detail by XPS and FESEM. The oil contact angle increases to 158.6±8.0° and the sliding angle decreases to 3.9° for the PSBMA/PDA-modified ones, indicating superoleophobic underwater and ultralow adhesive towards oil. They are stable towards organic solvent treatment, and retain the wettability in sea water for long time. The PSBMA/PDA-modified PPMMs was fabricated with the same method. Significant improvement is demonstrated for the surface hydrophilicity by results of water contact angle and pure water flux. Dynamic protein filtration experiments confirm the excellent antifouling property of the resulted membranes. However, PEG is not suitable in the co-deposition with PDA. The deposition density dncreases obviously with increasing the PEG concentration. The PEG/PDA-modified PPMMs show high quantity of adsorbed (Bovine serum albumin) BSA, which results in absence of antifouling property.Then, we report the LBL assembly of PSBMA and PEG with TA to study the co-deposition mechanism. The assembly process was monitored by QCM and UV/Vis spectroscopy. The surface morphology and chemical composition were characterized by FTIR/MR, XPS, VASE and AFM. The result indicates there is electrostatic interaction between PSBMA and TA, which is strong enough to keep (TA/PSBMA)n multilayers stable over a wide pH range of 4-10 and in saline, such as 1 M NaCl or urea solution. In contrast, the LBL of (PEG/TA)n follows exponential Growth and are driven by the weak hydrogen bond, leading to the instability in the alkaline solution. Furthermore, (TA/PSBMA)n multilayers show high hydrophilicity with a water contact angle lower than 15°. Adsorption amounts of BSA, lysozyme (Lys), and hemoglobin (Hgb) decreased to 0.42,52.9, and 37.9 ng/cm2, respectively.PSBMA and POEGMA were grafted on PPMM surface via UV-induced graft polymerization. Protein adsorption and filtration results indicate that both of the PSBMA-and OOEGMA-grafted membranes have excellent hydrophilicity and antifouling capability. However, their oxidative stability against H2O2/Cu2+ and NaClO solutions is remarkably different. FT-IR/ATR XPS and TOF-SIMS analyses show that polySBMA degrades faster than polyOEGMA in the oxidation process, mainly due to the ester hydrolysis and elimination of sulfobetaine units. After oxidation, the PSBMA-grafted membrane has an increased water contact angle from 36° to 118° and deteriorated antifouling capability, whereas the polyOEGMA-grafted one almost maintains the surface properties. PSBMA/POEGMA-grafted PPMMs were also fabricated via the same polymerization method. The fluxes were decreasing obviously with increasing NaCl concentration of solutions.