Video: Assembling a stronger self-healing hydrogel
S. Himmelstein | December 27, 2019A new approach to the formulation of robust self-healing hydrogels was inspired by the mussel, which can Controlling pH enables reversible hydrogel formation in wider range of metal concentrations. Source: MITproduce, break and reform byssal threads for anchorage. The materials development from MIT can be used to create new polymer classes with biomedical applications.
Nitrocatechol, a modified mussel-inspired coordinating ligand, was attached to polyethylene glycol. This hydrogel system was coordinated with iron, and a second material based on histidine was coordinated with nickel. The cross-linked metal coordination bonds required to yield strong hydrogels occurred under pH-controlled competition conditions. Strong cross-links evolved even under excess metal concentrations, confirming the role of hydroxide ions as competitors to the polymer for binding to metal.
Polymers bind to metal atoms in ones, twos or threes, but when more metal atoms bind to the hydroxide ions, there are fewer metal atoms free to connect with polymer atoms. Under these conditions, polymer atoms will bind to metal atoms in strong triple cross-links that produce a stronger hydrogel network.