Double hydrogen-bonding pH-sensitive hydrogels retaining high-strengths over a wide pH range.

Traditional pH-sensitive hydrogels inevitably suffer strength deterioration while the responsive weak acid or base groups are in the ionized state. In this study, we report on a facile approach to fabricate a novel pH-sensitive high-strength hydrogel from copolymerization of two hydrogen-bonding motif-containing monomers, 3-acrylamidophenylboronic acid and 2-vinyl-4,6-diamino-1,3,5-triazine with a crosslinker N,N-methylenebisacrylamide through hydrophilic optimization of the comonomer oligo(ethylene glycol) methacrylate. The double hydrogen bonding hydrogel exhibits both high tensile and compressive strengths over a broad pH range due to the unique ability to maintain at least one type of hydrogen-bonding crosslink over the whole course of pH change.