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The influence of fringe electric field applied during photopolymerization on the electro-optic properties of polymer-stabilized blue phase liquid crystals (PS-BPLCs) was investigated. It has been found that the thermal stability would not degrade if the electric field was less than a critical value. The contrast ratio of PS-BPLC can be improved significantly because the uniformity of blue phase liquid crystal domain was enhanced by the electric fields, which were applied during photopolymerization. Meanwhile, with the electric filed, the potential energy of the BPLC molecules may lower the anchoring energy of the polymer network resulting in the improvement of electro-optic response properties. With optimized electric field during polymerization, the contrast ratio and the Kerr constant of PS-BPLC can be improved by 4.1 times and 15%, respectively, and the hysteresis can be decreased by 10%, while the response time and residual birefringence have no degradation.

We investigated random lasing from a fluid self-assembly sphere-phase liquid crystal, which was composed of three-dimensional twist sphere structures with disclinations among them. The threshold energy of the random lasing from sphere-phase liquid crystal was 32% of that from the chiral nematic phase because of the interference associated with multiple scattering by randomly distributed sphere-phase platelets. Such random lasers composed of self-assembly soft organic materials may be useful for holographic displays, point-of-care biomedical analysis, and optical security coatings.

Segmented ZnS nanocones have been prepared at 1200 degrees C by thermal evaporation of zinc sulfide powders and catalyst metal tin. The as-synthesized products have been studied by energy-dispersive x-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. Microstructure characterization indicates that the formation of segmented nanocones can be attributed to the effects of regular twins structure. Theoretical analysis reveals that the nonuniform cross sections of nanocones are related to the continuous change of Sn-ZnS liquid droplet's scale resulting from the supply of Sn atoms during the evaporation. According to microstructure characterization and dimension analysis, the potential formation mechanism of the segmented ZnS nanocones was discussed. (C) 2005 American Institute of Physics.