Response Behavior And Optical Properties Of 2D/3D Temperature-sensitive Photonic Crystal Hydrogels

Photonic crystal(PC)is a structural material with spatial periodicity,which is mainly formed by self-assembly of monodisperse latex particles.Under external stimuli such as temperature,p H,and solvent,its volume can expand and contract in linear size changes.With the change of size,a chemical sensor with visual and real-time detection can be prepared.However,currently photonic crystals are usually prepared from"hard spheres"(such as polystyrene),but they have the disadvantages of easy cracking,single response,and poor defect tolerance.In this paper,a poly(N-isopropylacrylamide-co-tert-butyl acrylate)(Poly(NIPAm-co-t BA))was prepared by soap-free emulsion polymerization.2D photonic crystals and crack-free 3D photonic crystals were prepared by the tip flow method,horizontal deposition method,and high-speed centrifugation method.The chemical composition,particle size and distribution,response performance,and optical properties were studied.Part of the job:1.The micro-gel spheres were prepared into 2D photonic crystals by the tip flow method.In order to overcome the shortcoming of the structure being easily destroyed,they were combined with a semi-interpenetrating network hydrogel with excellent mechanical properties to prepare a warm Sensitive photonic crystal composite gel film.The chemical composition of the product was confirmed.The effects of the molar ratio of t BA/NIPAm on the hydrodynamic diameter(D_H),monodispersity(PDI),micro-morphology and temperature sensitivity of microgel beads were systematically studied.The response behavior of photonic crystal composite gel film under temperature and external force was investigated.The results showed that with the increase of the volume ratio of t BA/NIPAm,the D_H of the microspheres decreased from 712.2 nm to 529.2 nm,the PDI was good,and the temperature sensitivity gradually decreased;when the photonic crystal composite gel film is stretched at different magnifications,the microspheres gradually change from spherical to ellipsoidal and the spacing gradually increases;and the diffraction wavelength shifts red,the diffraction intensity decreases;when the temperature is increased,the microgel spheres shrink,the spacing increases,and the diffraction peaks shift red and the intensity becomes weak.2.Based on Poly(NIPAm-co-t BA)microgel spheres,different types of 3D photonic crystals were prepared by horizontal deposition and high-speed centrifugation,respectively.The macro,micro structure and optical characteristics were analyzed,and the response behavior of the 3D photonic crystal under different temperature,humidity and ion conditions was systematically studied,and the assembly and response mechanism of its microgel beads were clarified.The results show that the 3D photonic crystal prepared by the horizontal deposition method is red-shifted with increasing humidity,and the process is very repeatable;the 3D photonic crystals prepared by high-speed centrifugation undergo blue shift with the increase of temperature and ion concentration;it shows that these two 3D photonic crystals have potential application value in the detection of temperature,humidity and ion concentration.