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

Abstract

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.

Keywords

photonic crystals / inverse opal / physical cross-linking / thermal-responsive / nanocomposite hydrogel