Tg Controlled Polyacylates Structural Color Materials Based On Photonic Crystal

Photonic crystals have attracted wide attention in the fields of sensing response,color displaying and packaging due to their unique structure and color rendering mechanism.However,these photonic crystal materials still have some problems,such as small area,dull structural color,and poor structural stability,which limit their wide application in practice.Thus,polyacrylate microspheres as the core,different synthesis paths are designed for improving the preparation area,color quality and structural stability of materials respectively.The specific work is as follows.A scheme of "self assembly-partial fusion-transfer" on the water-air interface is designed to prepare large-area self-freestanding photonic crystal film by using the characteristics of polyacrylate microspheres that are prone to deformation and fusion under conditions higher than Tg.Poly(butyl methacrylate-co-methylmethacrylate-co-butyl acryllate-co-diacetone acrylamide)(PBMBD)microspheres with slightly hydrophilic(CA 86?)and low glass transition temperature(27?)were synthesized and self-assemble into a large area periodic ordered structure with high quality on the water-air interface.By adjusting the temperature,the adjacent microspheres can be partially fused to form a self-freestanding film that keeps the internal period.The material can reach an area of 30 cm×21cm or more.After touching water,it can present a bright and uniform structural color.In addition,Poly(butyl methacrylate-co-methylmethacrylate-co-butyl acry late-co-methacry lic acid)(PBMBM)microspheres with hydrophilic functional group COOH have substituted for PBMBD microspheres,and the large area photonic crystal prepared of PBMBM microspheres can respond to pH>7 water solution by using the above synthesis route,indicating that this synthesis mechanism has a popularized range of application.Poly(butyl methacrylate-co-methylmethacrylate-co-butyl acrylate)(PBMB)microspheres below Tg are used as core for PBMB@SiO2 microspheres to coat SiO2.The hollow SiO2 photonic crystal film are prepared by lifting-assembling PBMB@SiO2 microspheres and then calcining.By controlling the calcination temperature at the critical decomposition temperature of PBMB,the carbon black composition up to 15.1%can be retained in the hollow SiO2 photonic crystal structure after calcination,so as to absorb background light scattering and improve the structural color saturation,making the hollow SiO2 photonic crystal structure present a bright structural color.Two kinds of hollow SiO2 chromophotonic crystal materials with high saturation are obtained namely malachite green(particle size 284 nm)and deep purple(particle size 242 nm)respectively.Hollow SiO2/PHMP composite photonic crystal films with high structural stability are prepared by combining Poly(2-hydroxyethyl acrylate-co-methacrylic acid-co-polyethylene glycol diacrylate-250)(PHMP)polymer as filling material with hollow Si02 photonic crystal.Hollow SiO2 PC films with particle sizes of 284 nm,242 nm,and 205 nm were used as templates,and PHMP monomers with glass transition temperature of 58? were filled to form freestanding hollow SiO2/PHMP composite photonic crystal films after polymerization.Based on the high mechanical strength of PHMP and the skeleton support function of hollow SiO2 ordered array,this composite structure film has very good structural stability.Its mechanical tensile strength and compression strength can reach 51 MPa and 99 MPa respectively.The structural color remains invariable during mechanical stretching or compression(<30 MPa).And its structural color remains unchanged in natural light for half an year.Based on Tg controlled thermoplastic property of PHMP,the composite photonic crystal film can also be flexibly hot-processed to form a three-dimensional shape that can be maintained after cooling.This three-dimensional shape programming has considerable application value in photonic crystal-based packaging or decoration.