Supramolecular hydrogel hybrids having high mechanical property, photoluminescence and light-induced shape deformation capability: Design, preparation and characterization

Integration of property, function, and intelligence in one single material obviously can further exploit applications of hydrogels, which remains a challenge. Physical mixing or chemical grating of functional components into hydrogels cannot easily achieve this goal. Here, we designed a new approach to prepare supramolecular hydrogel hybrids that presented high mechanical property, good photoluminescent function, and evident light-induced shape-deformation intelligence. Hydrogen bonding was constructed between nitrates in rare earth organic complex of Sm(TTA)Phen(NO₃)₃ (STPN) (TTA and Phen stand for α-thenoyltrifluoroacetone and 1,10-phenanthroline) and carboxyl groups in smart hydrogel networks. A facile solution mixing step without any harsh conditions allowed the successful preparation of hydrogel hybrids, which was suggested by the results of FTIR, ¹H NMR and UV–vis spectrophotometer. The compressive strength of hydrogel hybrids was increased greatly from 50 to 556 kPa after mixing STPN, while evident photoluminescence was demonstrated as well. More importantly, the presence of STPN enabled such supramolecular hydrogel hybrids to increase their temperatures and to contract shapes under the irradiation of near-infrared light at 1064 nm. This work provides a simple method to create supramolecular hydrogel hybrids that can be potentially used in the fields of soft actuators, drug delivery carriers, and so on.