Preparation And Application Of Liquid Colloidal Crystals

Liquid colloidal crystals have unique physical and chemical properties,such as fluidity,metastable structure,and reversible assembly and disassembly.Therefore,they have unique advantages in large-scale preparation of colloidal crystal materials and construction of responsive photonic crystals.Regrettably,the preparation of liquid colloidal crystals often requires a long period of standing to precipitate and lacks effective synthesis methods;and the difficulties in synthesis and preparation have led to the lack of research on the application of liquid colloidal crystals,which greatly restricts the development of this material.In order to solve the above-mentioned key scientific problems,this thesis will carry out targeted research on new methods for preparing liquid colloidal crystals,assembling intermediates of liquid colloidal crystals,and exploration of new responses of liquid colloidal crystals.The results are as follows:In Chapter 2,we developed a new method for preparing liquid colloidal photonic crystals based on the liquid-liquid extraction process.Studies have shown that the use of single-component and two-component extractants with moderate polarity can selectively extract the solvent components in the colloidal solution,thereby effectively concentrating the colloidal solution without causing agglomeration of colloidal particles,and finally spontaneously precipitated and formed Liquid colloidal crystals.The method provides a universal,convenient,rapid and large-scale room temperature synthesis method for synthesizing liquid colloidal crystals composed of different colloidal particles/solvents.The utilization rate of the colloidal particles in the method is 100%,and the separated extractant can be reused after being purified by lowtemperature distillation,which can realize the green preparation of liquid colloidal crystals.In Chapter 3,we developed a new method for preparing liquid colloidal crystals based on porous adsorption.The method realizes the controllable concentration of the colloidal solution through the adsorption of the porous substance to the solvent in the colloidal solution,thereby driving the colloidal particles to spontaneously precipitate to form liquid colloidal crystals.The method is suitable for various colloidal solution systems,and solves the problem that the volatilization-driven supersaturated precipitation method cannot prepare low-boiling liquid colloidal crystals.In Chapter 4,we use the liquid colloidal crystal as the colloidal assembly intermediate to develop a new two-step spraying method to prepare a highly crystalline,bright and bright photonic crystal car paint coating.The key of the method is to select a two-component solvent with suitable surface wettability and volatilization speed to make a colloidal solution,spray to quickly form a completely covered liquid colloidal crystal intermediate,and finally transform it into a highly crystalline photonic crystal film.This kind of photonic crystal has a very narrow optical forbidden band and excellent monochromaticity.Therefore,by simply adjusting the size of the colloidal particles,monochromatic coatings such as red,yellow,green,and blue with high saturation can be obtained;it is also based on monochromatic coatings.For chromaticity,we can stack two primary colors(photonic crystal structure)to obtain various spectral and non-spectral colors with continuous gradients between "red-green-blue".This new technology for preparing photonic crystal structure color coatings is fully compatible with modern car paint processes,and the prepared photonic crystal coatings have unique angular discoloration effects,good chemical and mechanical stability,and have broad applications in the field of automotive coatings.In Chapter 5,we found that liquid colloidal crystals have a sensitive response to the generation and quenching of free radicals.Using dynamic reflectance spectroscopy,not only can the relative activity of different photoinitiators to generate free radicals be judged,but also the initiation activity of a single initiator to different active monomers can be judged.Although the above response cannot determine the absolute amount of free radicals generated in the liquid colloidal crystal,the relative amount of free radicals in parallel systems can be compared horizontally through dynamic reflectance spectroscopy,which provides a convenient new way for the detection and identification of free radicals.