Fabrication And Properties Of Tin Dioxide-Based Inverse Opal Photonic Crystals

SnO2 has excellent chemical stability and thermal stability,and is hard to dissolve in acids and alkalis.It is an ideal material for constructing inverse opals with structural colors because of its intrinsic white color and relatively high refractive index,which is 2.00.However,the rigid structure of SnO2 inverse opal results in high brittleness,makeing it difficult to achieve external stimulus response by changing their lattice parameters.Moreover,their strong incoherent light scattering ability causes low color saturation.In this thesis,polystyrene(PS)opals were used as templates to construct SnO2 inverse opal with various pore sizes.The as-prepared SnO2 inverse opals were ultilized to construct structural-color systems,which show thermal response and can be used for anti-counterfeiting,by combining with organic phase change materials.Moreover,the color saturation of SnO2 inverse opals was improved via in-situ carbon doping or Fe3+ doping,which can effectively shield the interference of background light.Structuralcolor composite films with enhanced color saturation and mechanical properties were prepared by combining Fe3+-doped SnO2 inverse opals with elastomer.PS spheres with regular spherical structure and narrow diameter distribution were prepared via emulsion polymerization,and their average diameters can be adjusted in a range from 200 nm to 470 nm.The PS microspheres with average diameters of 2O2 nm,234 nm and 274 nm were assembled into opal photonic crystals with blue,green,and red colors via a thermalassisted self-assembly method,whose process was studied and optimized with the help of dynamic spectral detection.Further,the PS microspheres with average diameters of 310 nm,355 nm and 451 nm were assembled into opals and used as templates for constructing SnO2 inverse opals.Accordingly,the SnO2 inverse opals,which were prepared via a direct template method,has average pores sizes of 213 nm,242 nm,and 315 nm,and correspondingly show blue,green,and red structural colors.Polyethylene glycol(PEG)and thermochromic phase transition system with aliphatic alcohol as solvent(FA-TC-PCS)were filled into SnO2 inverse opals to construct PEG/SnO2 and FA-TC-PCS/SnO2 composite systems with thermal response,respectively.Driven by thermal,PEG undergoes a phase transition from solid to liquid,accompanied by the switch of light scattering and light transmission,thus achieving the light path control.In detail,the structural color is hidden by crystalline PEG because of its strong light scattering,and displays when PEG is in molten state because of its good light transmission.For the FA-TC-PCS/SnO2 system,the thermal-responsive dye can realize the switch of color and colorless under thermal stimulis,thus achieving the light path control.In detail,the structural color is hiden by the crystalline FA-TC-PCS because of the light absorption of dye molecules,and displays when the FA-TC-PCS is in molten state because of its good light transmission.Photonic crystal patterns were combined with these phase change systems,and they can hide or display based on the thermal response.The color saturation of SnO2 inverse opals was effectively improved via in-situ carbon doping or Fe3+ doping,which made them realize background light self-shielding.Further,polydimethylsiloxane(PDMS)was filled into Fe3+-SnO2 inverse opals to construct composite films with high color saturation and strong toughness.