Polyoxometalate-Based Photochromic Supramolecular Hydrogels with Highly Ordered Spherical and Cylindrical Micellar Nanostructures.

Polyoxometalates (POMs) have attracted much attention in the field of photochromic materials. However, POM-based photochromic supramolecular hydrogels with high transparency and good photochromic properties are seldom reported. In this work, a homogenous, optically transparent, injectable, and photochromic supramolecular hydrogel was fabricated through the coassembly of ammonium heptamolybdate (Mo ) and an imidazolium-based zwitterionic amphiphile (3-(1-hexadecyl-3-imidazolio)propanesulfonate (C IPS)). The balance between electrostatic attraction and repulsion of Mo clusters and zwitterionic amphiphiles enables them to coassemble into a homogenous and transparent supramolecular hydrogel. By adjusting the molar ratio of C IPS/Mo , ordered spherical micelle-based hydrogels and aligned wormlike micelle-based hydrogels can be obtained. The incorporation of Mo into hydrogels endows these hydrogels with excellent photochromic properties. Specifically, after coassembly with C IPS, the photochromic ability of hydrogels is significantly enhanced compared with that of a pure aqueous solution of Mo . These hydrogels exhibit great potential applications as photochromic materials for the recording of rewritable information.