Thermal-responsive Photonic Crystals based on Physically Cross-linked Inverse Opal Nanocomposite Hydrogels

A thermal-responsive photonic crystal material was fabricated by forming an inverse opal nanocomposite hydrogel of poly(N-isopropylacrylamide) (IONH PNIPAm ) within the interstitial space of a polystyrene photonic crystal template. In IONH PNIPAm , PNIPAm were physically cross-linked with two kinds of nanoparticles (carbon dots and laponite clays). The integration of carbon dots and laponite clays for physical crosslinking endowed IONH PNIPAm sufficient strength and self-healing property. IONH PNIPAm films can be completely peeled from the substrates to be utilized as an independent photonic crystal material. The structural color and optical diffraction of the IONH PNIPAm exhibits a rapid reversible change in response to external thermal stimuli due to its physical cross-linking feature. Moreover, the IONH PNIPAm shows clear fluorescence due to the introduction of carbon dots, which enables a convenient way for chemical detection (such as the detection of silver ions). This stimuli-responsive photonic crystal materials based on physically cross-linked inverse opal nanocomposite hydrogels with fast response and good mechanical stability are promising for applications in the fields of smart optical detectors, thermal-responsive sensors and chemical detectors.