Kishiro Iwasaki

Solubility parameters of liquid crystals

Solubility parameters are introduced for the first time to investigate the solubility problem of liquid crystals. Using Fedors method that is used for polymers and organic solvent gives solubility parameters of liquid crystals in the range of 8.0 (cal/cm 3 ) 1/2 to 11.0 (cal/cm 3 ) 1/2 . Polar liquid crystal compounds have large solubility parameters compared with nonpolar ones. Moreover, an aromatic ring, which is frequently encountered in liquid crystal compounds, increases the solubility parameter value. Since these parameters can be used to calculate the activity coefficient in regular solution theory, we attempted to investigate the solubility of solids and gases for two types of liquid crystal solvents, namely a polar nematic liquid crystal solvent and a nonpolar one. We found that the solvent dependence could be explained by the solubility parameter difference between a solute and a nematic liquid crystal solvent.

Organic Optical Storage Medium with a Read-Out Stability under 1 mW Laser Irradiation

The basic characteristics of new naphthalocyanine derivatives used as a recording layer for a write-once optical storage medium were studied. Read-out stability could be improved by mixing two types of naphthalocyanines: one had a bulky structure with large side chains on the central atom, while the other had a flat structure. The stability of the medium under 1 mW laser irradiation for read-out was substantially improved by a hundredfold times compared with that of a single-component system.

The effects of material constants and device parameters on electrooptic characteristics of liquid crystal devices

Abstract The effects of liquid crystal (LC) material constants and cell parameters on electrooptic characteristics which control multiplexability of twisted nematic liquid crystal devices (TN-LCDs) were investigated on the basis of Δnd/Λ dependence. Computer simulations were carried out using Berremans method, and some of the results were verified by experiments. Influence of dielectric and elastic constants on electrooptic characteristics were found to differ with Δnd, smaller Δe/e1, K22/K11 and K33/K11 ratios gave smaller threshold sharpness. Only a small change in low pretilt angles was sufficient to produce a large effect on threshold sharpness. Electrooptic characteristics were significantly influence by changes in settings of the polarizer and analyzer.