Improvement of Light Switching Contrast of Liquid Crystalline Composite Gel by Adding Polar Organic Solvent

Abstract

Downloaded by [UQ Library] at 18:13 15 June 2015The aggregation structure and electro-optical properties were investigated for novel liquid crystalline composites composed of a low molecular weight gelator and a low molecular weight liquid crystal. The gelator spontaneously aggregated through intermolecular hydrogen bonding and formed spherulite-like and fiber-like aggregation structures in the composite. By the addition of a solvent with a high dielectric constant and a large dipole moment, such as dimethyl sulfoxide, the number of the spherulite-like structures in the composite decreased strikingly due to affecting the hydrogen bonding of the selfassembling gelators in the composite, resulting in a higher light transmission state upon an application of an a.c. electric field. Dimethyl sulfoxide was found to be an effective agent for improving the electro-optical properties of (gelator/ liquid crystal) composite gel.

Effects of size, capping agent, and concentration of CdSe and CdTequantum dots doped into a nematic liquid crystal on the optical and electro-optic properties of the final colloidal liquid crystal mixture

“…Oversimplified, rather than the entire bulk of the molecules reorienting all at once to produce the opposite bulk alignment state, individual micro-domains reorient independently, effectively decreasing the applied potential required for the re-alignment. There is considerable evidence for lower (or at least altered) V th values for nematic phases with a micro-domain structure from polymer-stabilized nematics [74][75][76] as well as nematic phases containing networks of a gelator (nematic gels). [77][78][79] Another way by which the QDs may affect the electro-optic parameters of the nematic host is by increasing the capacitance in the system.…”

Functional π-Gelators and Their Applications

“…The strong intermolecular interactions between the LC and the gelator enabled to orient the gelator molecules either in parallel or perpendicular to the molecular long axis of the LCs. Extensive studies have shown that a pool of gelators could be dispersed in LC gels to get functional assemblies with properties such as electrooptical switching, stimuli responsive or photothermal control, photopolymerization, anisotropic charge carrier transport, electronic conductivity, polarized emission etc. ,− Thus, the anisotropic physical gels help to the development of photo/electro active or stimuli responsive materials that are useful in advanced applications.…”

Chirality-Enabled Liquid Crystalline Physical Gels with High Modulus but Low Driving Voltage

“…In addition, LC physical gels promise applications in large-area, ultra-thin, flexible LC displays, where mechanical robustness and facile electro-optic responses are needed . Cooling methods, solvent polarity, metal ions, gelator substitutes, alignment conditions , and other factors show remarkable influences on the microstructure and performance of LC physical gels. Thus, constant efforts have been devoted to boost the mechanical resistance or to lower down the driving voltage of LC physical gels.…”