Preparation And Performance Of A Reversible Solvent Sensitive Liquid Crystal Elastomer-colloid

Three-dimensional periodic dielectric materials are theoretically proved to have the ability of photonic band gap.Such materials are called photonic crystal.Photonic crystal materials play an important role in the field of controlling and manipulating the optical materials of light propagation.They have a broad application prospect in the fields of catalyst,sensing,high performance optical devices and so on.In order to improve the optical quality of colloidal photonic crystals and achieve excellent optical signals for the wide application of photonic crystal based optical devices,a variety of new materials and assembly structures have been developed.Liquid crystals exhibit great optical anisotropy due to their anisotropic molecular shape and orientation.The application of light,temperature,solvent and electric field can easily adjust the refractive index of liquid crystal.Liquid crystal elastomer is a moderately crosslinked liquid crystal polymer network,which combines the elastic characteristics of the polymer elastomer with the self-assembly characteristics of liquid crystal.The most obvious feature of liquid crystal elastomers is that they can change shape reversibly after external stimulation.If the liquid crystal elastomer loses its anisotropy,for example,the liquid crystal elastomer is heated to isotropic phase,the chain conformation of the isotropic phase will be adopted,so the whole sample as a whole will have to change its shape.That is to say,the changes of molecular conformation on the micro scale of liquid crystal elastomer are shown as bending,crimping and folding of the film macroscopically.Liquid crystal elastomer has important applications in artificial muscle,artificial iris,micro robot,fluid transportation,controllable optical devices and so on.In this paper,a reversible solvent-sensitive the pure liquid crystal elastomer film and the liquid crystal elastomer-colloidal crystal film actuation are proposed.The liquid crystal monomer is overfilled into the colloid template and then UV photopolymerization is carried out.The integrated structure of liquid crystal elastomer and colloid was formed and the actuator was prepared.Based on the cleverly transition from inhomogeneous swelling process to uniform swelling process,the actuator can realize rapid continuous bending/unbending process in the same solvent.It is an interest mimic for the rapid anti-counterfeiting process of nature insect that catching prey and recovering toward the balanced state.The main contents are as follows:1.A series of monodisperse latex spheres with core-shell structure are designed and prepared by one-step method.Cormpared with the cornventional cavity surface structure,the colloidal crystal films have completely dense hollow structure and strong mechanical strength.This is due to the physical connection between the latex spheres and the strong bonding of hydrogen bonds.The photonic band gap adjustable colloidal crystal films with high mechanical strength are prepared by this simple method.It will promote the practical application of opal films in new generation optical devices and decorative materials,such as high performance reflectors,chemical,biochemical sensors and environmental protection color coatings.We also use a simple solution-based colloid/matrix co-assembly method to synthesize highly ordered inverse opal SiO2 films with less cracks.Since there is no overlay,the high porosity of composite film is easily obtained from the surface,which is useful for catalysis.The applications of gas adsorption or tissue engineering are particularly important.The single domain periodic antiopal films can also exhibit large photonic band gap structures and can be used in photonics.2.The solvent-responsive pure liquid crystal elastomer film and the liquid crystal elastomer-colloidal crystal film were prepared by UV polymerization using monoacrylate liquid crystal monomer,double acrylate liquid crystal crosslinking agent and photoinitiator.The effects of the length/thickness of pure liquid crystal elastomer film and liquid crystal elastomer-colloidal crystal film,the molar ratio of monomer and crosslinker and the type of solvent on the actuation performance of the film were studied.The experimental results show that the increase of the length and thickness of the pure liquid crystal elastomer film and the liquid crystal elastomer-colloidal crystal film will reduce the actuation angle and prolong the actuation time.Dichloromethane is a good solvent for pure liquid crystal elastomer membrane and liquid crystal elastomer-colloidal crystal membrane,which makes its swelling degree and actuation angle maximum.In this thesis,the pure liquid crystal elastomer film and the liquid crystal elastomer-colloidal crystal film with the size of 6 mm×1 mm×15?m have the best actuation performance.That is to say,by changing the above conditions,the actuation behavior of pure liquid crystal elastomer film and liquid crystal elastomer-colloidal crystal membrane can be adjusted effectively.3.Based on the dissolution of colloid particles and the anisotropy of bulk liquid crystal elastomer film,the liquid crystal elastomer-colloidal crystal film exhibits a continuous bending/unbending process in solvent.By designing different shearing angles,the multi-ring bending or spiral bending of the pure liquid crystal elastomer film and the liquid crystal elastomer-colloidal crystal film can be controlled.This work will provide important insights for the design and manufacture of new actuator materials.