Study On The Correlation Of Particle Size With Self-assembled Structure And Its Structural Color Effect

Structural color has typical properties including high brightness,high saturation,without fading and iridescent effect,if we can cleverly and reasonably apply it to textiles,its added value would be greatly enhanced.In the early stage of our group,we used electrostatic self-assembly method to fabricate polymer / inorganic nanoparticles structural color films on different fabrics.however,the effect of nanoparticle size on self-assembled structure,the relationship between structural color and its corresponding microstructure,the applicable range of single thin film interference theory were all not yet studied in depth.This study is based on the preliminary work of our research group,accurate description of the microstructure and its optical properties were investigated in different particle size to study the correlation of particle size with self-assembled structure and its structural color effect.This work will provide a theoretical supplement for the follow-up structural color research,and promote the development and application of biomimetic textile products.The major work could be summarized as follows:1.Study the effect of particle size on the self-assembled structure : the SiO₂/PEI thin film assembled in different particle size were characterized by scanning electron microscopy to observe their distribution on the substrate and the assembly behavior in the whole assembly process,and the atomic force microscope and ellipsometer were also used to study the difference of the SiO₂/PEI thin film's surface morphology and internal structure when it was assembled in different particle size;2.Study the effect of particle size on the structural color effect: structural color effect of the film assembled in different particle size were characterized by digital cameras,multi-angle spectrophotometer,UVvisible spectrophotometer,the uniformity,richness,brightness and iridescent effect of the structural color were taken as the evaluation indexes to study on the effect of particle size on the structural color effect;3.accurate description of the microstructure and its optical properties were investigated when assembled in different particle size,clarifying the complex relationship between the microstructure and the color effect,establishing the relevant theoretical model,specificating the applicable range of single thin film interference theory,and do some theoretical supplement.The main results were as follows:1.The particles with small size have little voids therebetween and the coverage ratio of the particles on the substrate is high,the filling and superposition behavior of particles are present during the whole assembly process,the film will form a multilayer structure and grow longitudinally,in contrast,the particles with large size charged more,they need to maintain a larger distance between each other to maintain the balance of the system,during the assembly process,the particles are preferentially filled into the gaps between the particles,until this layer is nearly saturated,then superposition behavior appears from scratch,the resultant film can be considered as a porous structure formed by organic/inorganic composite material and air pores;when the particle size is larger,the surface roughness of the film is more evident,air ratio of the internal structure is larger,and the film structure is also more loose;2.As the particle size increases,the number of assembly cycles when structural color begin to appear decreases,the color red-shifted when the number of assembly cycles increases;if the particle size is too large or too small,the structural color is very uneven and dark,the color changes less and iridescent effect becomes weak;color cycle phenomenon will appear during the increase of assemble cycles when the particle size is moderate;3.The structure of SiO₂/PEI films obtained in this study is macroscopically disordered,the scattering effect of light always exists,when the particle size is large,the surface of the film is undulated obviously,which will increase the surface scattering effect,and when the particle size is small,there will be some agglomeration and light diffraction effect between the particles,diffraction effect will also occur;the above-mentioned situation will weaken film interference effect in different degree,which will cause the film color becaming uneven,dark.