The Study On Preparation, Properties And Application Of Polymer/Liquid Crystal Composites

The combination of both polymer and liquid crystal to fabricate polymer liquid crystal devices, with the development of polymer materials, has attracted more and more attention. Polymer dispersed liquid crystal(PDLC) device has many advantages, such as preparing without polarizer, the simple operation process, realizing large-scale production and others. It not only improved properties of pure liquid crystal display in the field of display, also widely used in chemical, pharmaceutical, electronics etc. But with the development of the technology, the performance of pure PDLC can't meet the technical and practical requirements, which still need to study. Nowadays, the polymer liquid crystal polymer slices(POLICRYPS),a kind of new device,has become a hot spot of research which is a nano/micro composite structure made of slices of almost pure polymer alternated with films of well aligned nematic liquid crystal(NLC). There are many kinds of methods to prepare polymer liquid crystal device, wherein using the polymerization induced phase separation method is a promising method which has the advantages of liquid crystal droplet morphology of devices film regularity, uniform particle size distribution, simple operation and good repeatability.In this paper, the hybrid prepolymer solution preparation for PDLC made by the solution method which mixed NOA65 and E7 liquid crystal, then exposure by UV light to fabricated different system PDLC. The morphology of PDLC device observed by scanning electron microscopy(SEM), and electric-optical characteristic of the device also studied with applied different external electric field. The experimental results show that the system of polymer: liquid crystal=1:1 showed the best performance through balance the comprehensive properties of the threshold voltage and the response time. Besides, we also studied the different size silver nanoparticles with effects on the performance of PDLC Because of silver nanoparticles with localized surface plasmon resonance effect. The experimental results were characterized by two aspects of morphology and electro-optical properties. Experimental results show that the Ag particles of 20 nm has good effect on the threshold voltage, and Ag particles of 50 nm can shorten the response time of device.Further, LCDA hybrid solution prepared using the same method through mixing prepolymer and E48 liquid crystal. The preparation of LCDA device by the visible light induced phase separation using maskless lithography technology in the thickness of 20 ?m cell. We explored the optimized experimental condition to realize completely separation between liquid crystal and polymer, including the exposure time, exposure intensity, film thickness. Then the LCDA device was prepared under the optimum conditions. The morphology of membrane with applied different external voltage characterized through the polarizing microscope(POM), and the focusing effect of LCDA array recorded by CCD. The relatively complete phase separation realized through optimizing the conditions. The experimental results showed that the threshold voltage of the device is 4 V, the focus is polarization independent when the applied voltage is larger than the threshold voltage, which makes our devices fabricating with maskless lithography have applications in potential in the micro lens array.