Preparation And Application Of Self-crosslinking Photonic Crystals On Textile Substrates With Asymmetric Wettability

Photonic crystal is a kind of ordered microstructure materials which are periodically arranged by two or more kinds of materials with dielectric constant in space.By controlling its band gap position,it can show the effect of structural color in the visible range.At present,researchers pay close attention to the research of textile coloring by constructing photonic crystal chromogenic structure on textile substrate.However,due to the flexibility,coarseness and multi-level of textiles,the stability of photonic crystal chromogenic structure constructed on textile substrate is poor.When it is subjected to folding,bending,rubbing and other external forces in the practical application process,it is easy to collapse and fall off,resulting in the reduction of structural color,which seriously restricts the practical application of photonic crystal in the textile field.Therefore,how to obtain stable photonic crystal chromogenic structure on textile substrates has become a hot research topic in recent years.In order to improve the stability of photonic crystal chromogenic structure,we designed and prepared structural element with self-crosslinking characteristics.A plasma surface modification technology is used to provide an asymmetric wettability for textile substrates.Then,a vivid and stable photonic crystal chromogenic structure are constructed on textile substrates by digital jet printing technology,which will provide theoretical support and practical basis for the further application of photonic crystal structural color.The main research contents of this thesis include the following three aspects:(1)The self-crosslinking poly(styrene-N-hydroxymethyl acrylamide)(P(St-NMA))colloidal microspheres were designed and prepareed by soap-free emulsion polymerization,and the effects of polymerization parameters on the particle size distribution and monodispersity of the microspheres were investigated.The surface morphology,structural composition,element composition,glass transition temperature,electrification and stability of the microspheres were systematically characterized.The adhesion properties between colloidal microsphere film and textile substrate were discussed,and the self-crosslinking process was analyzed.(2)The textile substrate with asymmetric wettability was prepared by water repellent pretreatment and plasma technology.The influence of plasma treatment conditions on the wettability of textile substrate was investigated.The optical properties and stability of photonic crystal chromogenic structure constructed on different wettability substrates were characterized.The self-assembly process of microspheres on asymmetric wettability textile substrate was analyzed.The stability of photonic crystal chromogenic structure was tested and evaluated by bending and friction tests.(3)In this paper,P(St-NMA)colloidal microspheres with self-crosslinking properties were used as structural units to construct patterned photonic crystals with both bright color and stable structure on asymmetric wettability textile substrates by digital jet printing technology.With P(St-NMA)colloidal microspheres as the main system structure of ink,the effects of microspheres concentration,self-assembly temperature,p H regulator,surface tension regulator and viscosity regulator on the system were discussed.The optical properties of the printed photonic crystal chromogenic structure were analyzed and the stability of the photonic crystal was studied by immersion,bending and ultrasonic washing tests.The results showed that:(1)In the soap-free emulsion polymerization system,the size of P(St-NMA)colloidal microspheres increased with the increase of styrene dosage.With the increase of the amount of N-hydroxymethyl acrylamide and potassium persulfate,the particle size of P(St-NMA)colloidal microspheres decreased;The particle size range of P(St-NMA)colloidal microspheres is 200?350 nm,with good sphericity and monodispersity,obvious core-shell structure and good static stability;The strong adhesion between P(St-NMA)colloidal microsphere film and textile substrate is attributed to the self-crosslinking of hydroxyl groups on PNMA in P(St-NMA)colloidal microsphere and the formation of network structure.(2)When the plasma treatment power is 60 W,the treatment time is 60 W,the results show that the front contact angle of the substrate ranges from 80° to 90° while the back contact angle of the substrate is not affected,and the textile substrate with suitable asymmetric wettability can be obtained;The photonic crystals constructed on this wettability substrate are arranged regularly and tightly,and have obvious face centered cubic(FCC)stacking structure.At the same time,under this condition,the photonic crystals are loaded on the textile substrate in the form of "rooting",which significantly improves the stability of the photonic crystal chromogenic structure.After bending and friction tests,the photonic crystal structure did not fall off from the textile substrate,and the structural color does not decrease.(3)When the concentration of microspheres is 1.0 wt%,the amount of viscosity regulator sodium polyacrylate is 0?10.0 vol%,the dosage of surface tension regulator N-butanol is 0?0.5 vol%,the molar concentration of cross-linking accelerator hydrochloric acid is 0.05?0.10 mol/L,the dosage is 4.0?9.0 wt%,the ink with excellent ink-jet printing effect can be obtained;The results show that the surface tension of the ink is 63.79?71.20 m N/m,the p H value is 5?7 and the viscosity is 4.54?11.96 m Pa·s.After soaking,bending and ultrasonic washing tests,the photonic crystal still has good integrity and structure color rendering effect.