Research On Fabrication And Performance Of Noniridescent Structural-Color Patterns Based On Inkjet Printing Technology

Structural-color patterns have broad applications in the fields of sensors,displays,information security and other fields.Researchers have developed various preparation strategies to fabricate static and dynamic structural-color patterns to achieve their static recognition and dynamic sensing functions.In particular,there is a huge demand for photonic crystal patterns with dynamically responsive optical properties.Quasi-amorphous structures have attracted more and more attention in recent years,due to their stable angleindependent noniridescent structural-colors.Inkjet printing technology has significant advantages in directly writing complex patterns,but it is very difficult to create structuralcolor patterns by directly using ordinary inkjet printers,because fine control of micro-and nanostructures is required.Moreover,inkjet printing technology still faces the problems of low resolution and easy ink clogging.Based on inkjet printing technology,this thesis developed PS microsphere ink materials that meet the requirements of inkjet printing.By replacing traditional ink in ink cartridges with colloidal microsphere ink,the direct printing with noniridescent structuralcolor patterns is achieved.At the same time,a patterned silk fibroin film with a quasiamorphous inverse structure was successfully prepared by using the inkjet-printed structural color pattern as a template,and its optical and biological performances were studied.The main findings are as follows:(1)Preparation of inkjet printing ink:The structural color inkjet printing ink was prepared based on polystyrene(PS)microsphere dispersion.The effects of PS microsphere concentration,sodium dodecyl sulfate(SDS)solution concentration,and glycerol solution concentration on the surface tension,viscosity,pH value and conductivity of the ink were studied.Finally,the PS microsphere ink that meets the requirements of inkjet printing was successfully obtained.The optimal ink formulation contains 6%microspheres,0.5%SDS,and 4%glycerol.(2)Inkjet printing of noniridescent structural-color patterns:According to the comparative analysis results,the substrate material suitable for inkjet printing was selected.The experimental results show that the PET film has a flat surface microstructure and suitable surface wettability(the water static contact angle is 71.9±1.5°),showing the best pattern printing effect.On this substrate,based on inkjet printing technology,noniridescent structural-color patterns were successfully printed.The PS microspheres in the micropatterns exhibited a quasi-amorphous structure,resulting in noniridescent structuralcolors.Moreover,the color of the pattern can be effectively controlled by changing the size of the PS microspheres,and the shape of the printed pattern can be conveniently controlled by means of the characteristics of inkjet printing technology.The inkjet printing preparation strategy of the structural-color pattern has good practicability.(3)Preparation of patterned silk fibroin film with dynamic response optical properties:A patterned silk fibroin film with quasi-amorphous inverse structure was successfully prepared by using the inkjet-printed PS microsphere pattern as a template.The patterned silk fibroin film possesses stable structure and good flexibility under wet conditions,which has a high practical value.It exhibits no structural-color in the dry state,but rapidly shows a uniform bright structural-color pattern when immersed in water.Moreover,these two modes can be switched with each other.This dynamic response optical property is mainly due to the infiltration of water molecules into the polymer segments to regulate intermolecular hydrogen bonds,so that the internal structure of the film changes from a random arrangement to a quasi-amorphous structure,thus showing bright structural-color.(4)Biological performances of patterned silk fibroin film:The results of protein adsorption experiments showed that bovine serum albumin(BSA)can be actively and rapidly aggregated and adsorbed on the porous structure micro-regions of the patterned silk fibroin film,forming a green fluorescent stripe pattern consistent with the substrate pattern.After 12 h of adsorption,it tended to be saturated,and then the adsorption gradually slowed down.The results of cell culture experiments showed that the patterned silk fibroin film can effectively guide the cells to selectively adhere to the porous structure microregions.Compared with the unpatterned silk fibroin flat film,the patterned silk fibroin film can significantly promote the cellular growth behavior,showing excellent biocompatibility.