Organic–inorganic interpenetrating polymer networks and hybrid polymer materials prepared by frontal polymerization

Novel polyacrylamide-based hydrogels containing 3-(trimethoxysilyl)propyl methacrylate and/or tetraethoxy silane were synthesized by means of frontal polymerization, using ammonium persulfate as initiator, N,N0-methylene bisacrylamide as crosslinking agent and dimethyl sulfoxide as solvent. The obtained samples were treated at pH of 2 or 5 to induce the sol–gel reaction and evaluate their swelling behavior in the conditions. The occurrence of this reaction was assessed by solid-state NMR. Moreover, the thermal properties of the dry materials were studied by differential scanning calorimetry and thermal gravimetric analysis, and their water-contact angles were measured. It was found that the amount of Si affects the extent of swelling and the hydrophilicity of the resulting materials.