Polyacrylamide strengthened mixed-charge hydrogels and their applications in resistance to protein adsorption and algae attachment
Mixed-charge polymer hydrogels were successfully prepared by copolymerization of different ratios of [2-(meth-acryloyloxy) ethyl] trimethylammonium (TMA) and 3-sulfopropyl methacrylate (SA). Then, a second polyacrylamide (PAAM) network was incorporated into the pre-prepared hydrogel to form a double network (DN) hydrogel. The compositions of these DN hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Rheological and compressive measurements confirmed that the mechanical performances of the DN hydrogels were significantly improved by incorporation of a second PAAM network, compared with the according single network (SN) hydrogels. The amount of protein absorbed on the DN hydrogel surface was related to the ratio of TMA/SA and the ionic strength. The DN hydrogel with equal amount of TMA and SA exhibited better protein resistance. In addition, Phaeodactylum tricornutum and Chlorella were chosen for the anti-algae assay. The results displayed that the negatively charged hydrogels showed better anti-algae fouling performance than the positively charged and the neutral DN hydrogels. These DN hydrogels have promising applications in marine antifouling coating and interfaces of biomaterials.