pH-Tunable mechanical hydrogels prepared via transforming non C–C covalent synergistic interactions

In this manuscript, hydrogels with pH-tunable mechanical properties were prepared via transforming the non C–C covalent synergistic interactions of hydrogen bonding, metal ion coordination and hydrophobic effects. The fracture stress of hydrogels exhibited a tendency to firstly decrease and then increase with an increase of pH from 3.0 to 9.0. That is, the fracture stress was enhanced due to the synergistic interactions of hydrophobic effects and hydrogen bonding among carboxylic acid groups at pH 3.0. Then, the strength gradually decreased due to the disappearance of hydrogen bonding at pH from 3.0 to 5.0. Moreover, the fracture stress was also significantly enhanced at pH over 5.0 due to the synergistic interactions of hydrophobic effects and metal ion coordination. Consequently, it is envisioned that the strategy to design novel hydrogels with pH-tunable mechanical properties would provide more interesting directions for hydrogels based on non C–C covalent synergistic interactions in potential biomedical applications.