Preparation Of Photonic Crystals On Different Curvature Surfaces Via Spraying And Investigation Into The Properties

Photonic crystal structure color has the advantages of bright color and good environmental stability,and has been widely used in intelligent display and response,printing and printing,textile coloring and other fields.Currently,the reported preparation methods of photonic crystals can be mainly divided into impregnation method(gravity sedimentation method,vertical sedimentation method),digital printing method and spraying method,etc.,among which,because of the long assembly time of impregnation method,digital printing method is easy to block the nozzle and other factors,it is not suitable for large area preparation.Spraying method has the advantages of simple application,low cost and realization of photonic crystal film on curved surface.However,it is difficult to match the solvent volatilization and the self-assembly rate of microspheres in the preparation of photonic crystals by spraying method,which results in amorphous photonic crystal structures.In addition,in the process of constructing photonic crystal with curved surface by spraying method,there are some problems,such as uneven coating easily caused by unstable anchorage between assembly solution and substrate surface.In order to solve the above problems,the photonic crystals with high solid content were used as the spraying liquid to prepare the photonic crystals with high structural stability and high color saturation on the substrate surface of the special polymer pretreated bearing layer.And can be applied to different substrates,different curvature of the surface,increase the universality of its application.This paper mainly involves the following three aspects of research:(1)To construct the working fluid suitable for the preparation of non-cracking photonic crystal on the surface of two-dimensional planar substrate with iridic effect,and to study the effect of the volume fraction of nanospheres and anti-film cracking agent on the film formation of photonic crystal;On this basis,a pattern study was carried out to explore the influence of the bearing layer on the stability of the photonic crystal structure.The influence of mask mode on pattern definition and the influence of load layer number on the structural integrity of photonic crystal pattern mask removal.(2)The photonic crystal with iridescent effect is prepared by spraying on the three-dimensional curved surface.The effect of the assembly liquid system on the film forming performance of the assembly liquid on the curved surface was investigated.The influence of the viscosity of the assembly liquid on the film forming performance of the photonic crystal surface was investigated.The influence of the gun diameter and the concentration of the bearing layer on the uniform preparation of the photonic crystal was investigated.The main findings are as follows:(1)Preparation of two-dimensional planar substrate surface photonic crystals by spraying methodThe optimized composition of the liquid system for assembly work is as follows: the nanosphere emulsion with 30 wt% solid content made by the laboratory is reached.When the solid content is reached,the solvent volatilization time matches the self-assembly efficiency of the microsphere,and the orderly arrangement of photonic crystals can be prepared quickly.Planar non-cracking photonic crystal coatings can be prepared with the aid of anti-film cracking agent with the concentration of 6 wt%(weight of nanometer microsphere emulsion).After the assembly liquid system was determined,the spraying process was optimized.The amount of spraying liquid reached 15 g/m2,and the number of layers of the prepared nanospheres was thicker,which could strengthen the interference effect on the incident light and enhance the intensity of the reflected light.When the spraying distance is 30 cm,the droplets can uniformly fall on the surface of the substrate,and the photonic crystal structure color film with high color saturation and iridescent effect can be rapidly prepared by a single spraying.On this basis,the patterned study of the photonic crystal was carried out,and the photonic crystal layer was prepared after the hydrophobic bearing layer was constructed on the substrate surface.The concentration of the bearing layer was optimized to be 50%,and the surface of the bearing layer with this concentration was smooth and complete without obvious holes and depressions after the construction of the bottom and upper photonic crystals.When the amount of polymer in the bearing layer is 40 g/m2,the photonic crystal structure constructed on the surface has high structural stability(friction resistance,bending resistance,washable resistance),and can show high brightness structure color.Combined with mask method and spraying technology,the structure color pattern with clear outline can be prepared.The double-layer connected bearing layer is used as a bridge to connect the base layer and the photonic crystal layer,so that the patterned photonic crystal and the base layer are integrated to ensure the overall structure is stable.(2)Preparation of photonic crystals on the surface of three-dimensional curved substrate by sprayingThe microsphere solid content in the assembly solution is 40 wt% after optimization,which can be quickly assembled into uniform photonic crystal coating on the surface of curved surface.The film formation uniformity of curved photonic crystals can be improved by increasing the viscosity of the working fluid,but higher system viscosity will affect the assembly regularity of microspheres,and thus affect the iris effect of self-assembled photonic crystals.The bearing layer was prepared by spraying on the curved surface.When the concentration of the bearing layer was45 wt%,a homogeneous and complete polymer film with strong anchoring effect on the assembly working fluid could be prepared,so as to establish a surface suitable for microsphere self-assembly.Adjust the diameter of the spray gun to 0.3mm,the size of small droplets sprayed under the diameter is moderate,suitable for coating and self-assembly on the curved surface.The photonic crystals with obvious iridescent effect can be prepared by spraying on three-dimensional surface.