Thermally irreversible supramolecular hydrogels record thermal history

Abstract

A low-molecular-weight gelator produces a supramolecular hydrogel, which shows thermoreversible gel-sol transition. Here, we first report a thermo-“irreversible” hydrogel constructed from a novel low-molecular-weight gelator using dynamic covalent chemistry and its application to thermal history recording. The low-molecular-weight gelator, which was composed of a peptide, an alkyl chain and an aromatic ring, was synthesized via the Schiff base formation using a volatile aromatic aldehyde and an amine-terminated peptide amphiphile. The prepared hydrogel underwent gel-to-sol transition upon heating, which was similar to other reported supramolecular hydrogels. Interestingly, the resultant sol did not return to the gel state upon cooling under designed conditions, indicative of a thermo-irreversible hydrogel. We also demonstrated that thermo-irreversible hydrogels record thermal history without requiring electrical power for applications in logistics.