Polymerized Microgel Colloidal Crystals: Photonic Hydrogels with Tunable Band Gaps and Fast Response Rates

Into and out of the blue: The highly ordered structure of a PNIPAM microgel colloidal crystal (MCC) is stabilized by photopolymerization of its surface-bound vinyl groups. The resulting polymerized MCCs can respond reversibly and quickly to external stimuli, including temperature and ionic strength of the surrounding media, allowing the color and band gap to be finely tuned in the whole visible range.