Crystal Composite System Research Articles

Multilayer, Broadband Infrared Reflectors Based on the Photoinduced Preparation of Cholesteric Liquid Crystal Polymers.

This paper focuses on preparing broadband reflective liquid crystal films through the diffusion of monofunctional and bifunctional monomers in a photoinduced trilayer system. By combining the hydrophilic and hydrophobic liquid crystal glass surface treatment technologies, the polymer network of polymer-stabilized cholesteric liquid crystal (PSCLC) itself serves as a diffusion channel to form a trilayer cholesteric liquid crystal composite system containing bifunctional monomers, a nematic liquid crystal composite system, and a cholesteric liquid crystal composite system containing monofunctional monomers. Utilizing the difference in the polymerization rates of monofunctional and difunctional polymerizable monomers, the monomers and chiral compounds diffuse relative to each other, so that the liquid crystal pitch exhibits a gradient distribution, and the broadened reflective width can reach up to 1570 nm. There is no doubt that new and improved processes and technologies offer important possibilities for preparing and applying PSCLC films.

Preparation and properties of ZnO nanorod array/liquid crystal composite system

ABSTRACTIn this study, By hydrothermal reaction, we prepared ZnO nanorod array of high aspect ratio with different growth time. The prepared ZnO nanorod array was on one side of the liquid crystal cell, the another side of the liquid crystal cell is ITO-glass, then the ZnO nanorod array/liquid crystal composite was injected into the liquid crystal cell. Experimental results showed that the bandwidth of the reflection spectrum of the ZnO nanorod array/liquid crystal composite system was wider than the system without ZnO nanorod array. In addition, effects of polymerisation temperatures and the length of ZnO nanorod array on the broad-band reflection of N*-LC composite films were systematically investigated.

English

We report the determination of refractive indices of polymer dispersed liquid crystal composite within visible spectral range 404-706nm for various temperatures. The droplet domain formation effect in polymer liquid crystal composite system with variation of different polymer dispersed in liquid crystal and pure liquid crystal has been studied. The optical parameters due to scattering by sapphire prism have been measured for pure liquid crystal and polymer dispersed liquid crystal. It is found that the optical anisotropy of polymer dispersed liquid crystal composite system is greatly changed by polar order present in the polymer droplet environment. The scattering is due to both reorientation and thermal effects. The wavelength and temperature dependent refractive indices are fundamentally interesting and practically important for optimizing display performances and other photonic devices employing LCs such as high temperature gradient LCs, high thermal tunable LCs, and photonic liquid crystal fibers

Cd1-xZnxS/ZnS core/shell quantum dot ferroelectric liquid crystal composite system: analysis of faster optical response and lower operating voltage

Cd1−xZnxS/ZnS core/shell-structured quantum dot (QD)-doped ferroelectric liquid crystal (FLC) Felix 17/000 has been investigated in the present study. In the SmC* phase, the effect of QD on the dielectric and electro-optical properties of FLC has been studied as a function of dopant concentration. A substantial change in the different parameters like tilt angle, spontaneous polarisation, response time and relative permittivity has been observed for the composite system. Nearly two times faster response of the composite system with lower operating voltage is one of the promising results of the present study. The faster optical response along with the decreased value of spontaneous polarisation can be utilised in low power consumption liquid crystal displays.

Induced Smectic Phase in a (Nematic and Discotic) Liquid Crystal Composite System

The phase behavior and aggregation states of a binary composite system constructed from a nematic and a discotic liquid crystal have been investigated. The nematic liquid crystal E44 with a strong polar terminal group was miscible with the discotic liquid crystal R45C8 that possesses a flat core and eight soft side chains. This binary mixture showed an induced smectic phase in the range of 80/20–30/70 weight fractions. The d-spacing of this induced smectic phase is about 33–34 Å and the layer-stacking structure of a binary composite is proposed.

A Novel Phase Behavior and Optical Properties in a (Two Nematics/Cholesteric) Liquid Crystal Composite System

The phase behavior and optical properties of a liquid crystal (LC) composite (induced smectic phase formed by mixing two nematic LCs and one cholesteric LC) have been studied. The nematic liquid crystal 4-cyano-4′-pentyloxy biphenyl 5OCB with a strong polar terminal group was miscible with the nematic liquid crystal 4-hexyloxyphenyl-4′-pentyl benzoate HPPB having a weak polar terminal group. This binary mixture formed an induced smectic phase over a wide temperature range. The (induced smectic/cholesteric) ternary composite exhibited smectic A, cholesteric and blue phases. A novel phase was observed at the cholesteric-smectic phase transition region. The ternary system exhibited highly transparent and opaque states in the smectic and cholesteric phases, respectively, without the electric field.