A dipole-dipole reinforced copolymer hydrogel was synthesized by the one-step photopolymerization of vinylimidazole (VI) and acrylonitrile (AN) comonomer in the presence of a polyethylene glycol-based crosslinker. The mechanical properties of PVI-AN gels were tremendously increased by only chelating several mmol L À1 zinc ions, which was shown to firmly lock the temporary shape of the gel. Extraction of zinc ions by a complexing agent could facilitate the recovery of a permanent shape, and the memory behavior was reversible. The PVI-AN hydrogels supported the growth of L929 cells. The cell-seeded flat hydrogel sheet was folded into a temporary tubular scaffold and fixed in a culture medium containing 5 mmol L À1 zinc ions. After unfolding the tube, the exposed L929 cells were shown to adhere well on the surface of the gel. It is anticipated that this cell-loaded SM hydrogel could be fixed to a desired shape in vitro by small numbers of zinc ions for a potential implantable tissue engineering scaffold.

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.

Proton transfer is crucial for electrocatalysis. Accumulating cations at electrochemical interfaces can alter the proton transfer rate and then tune electrocatalytic performance. However, the mechanism for regulating proton transfer remains ambiguous. Here, we quantify the cation effect on proton diffusion in solution by hydrogen evolution on microelectrodes, revealing the rate can be suppressed by more than 10 times. Different from the prevalent opinions that proton transport is slowed down by modified electric field, we found water structure imposes a more evident effect on kinetics. FTIR test and path integral molecular dynamics simulation indicate that proton prefers to wander within the hydration shell of cations rather than to hop rapidly along water wires. Low connectivity of water networks disrupted by cations corrupts the fast‐moving path in bulk water. This study highlights the promising way for regulating proton kinetics via a modified water structure.