Gels and threads: mussel-inspired one-pot route to advanced responsive materials.

An inexpensive one-pot route to self-healing hydrogels with pH-tunable modulus is presented. Hydrogels were formed by reacting tannic acid, trivalent metal ions and polyallylamine. Below pH 8 the hydrogels were supramolecular while above, covalent cross-linking strengthened the hydrogels. From concentrated mixtures, threads were spun, acting as water sensitive mechanical locks.