Liquid crystal gel

Figure 1.20 Encapsulation of microdroplets of liquid crystals in ORMOSIL matrices results in materials with better transparency and thermal stability than polymer-dispersed liquid crystals. Gel-glass dispersed liquid crystal device switched between the OFF and ON state (thickness 10 pm, 4 x 2 cm, Fp p = 90V). (Reproduced from ref. 45, with permission.)...

Nowadays attention is turned also to the supermolecular level, that is, to the morphologic aspects, to the nature of interfaces, to the formation of new phases, or of particular aggregates (liquid crystals, gels, etc.). Interest has also been directed to the study of chain mobility for its influence on frictional properties of polymers. In recent years there have been many successful approaches to a microscopic theory (in contrast to a phenomenological approach) of the physi-comechanical behavior of macromolecular materials. 

Nonideal Behavior. The discussion of phase behavior up to this point represents the ideal case. A number of factors cause deviation from ideality. The phases present may include liquid crystals, gels, or solid precipitates in addition to the oil, brine, and microemulsion phases (39, 40). The high viscosities of these phases are detrimental to oil recovery. To control the formation of these phases, the practice has been to add low-molecular-weight alcohols to the micellar solution these alcohols act as cosolvents or in some cases as cosurfactants. 

Nematic gels are very interesting systems, thus deserving further study. Actually, these systems are being studied experimentally for applications. Examples are polymer dispersed liquid crystal displays are sometimes dispersed not in a polymer, but in a polymer network. Displays by means of the polymer stabilized cholesteric texture change, are also achieved in crosslinked systems. In addition, the chiral smectic phase has been obtained in such systems as well. Other types of liquid crystal gels have been applied or are expected to be applied in such devices. 

Huang CH, Zhang Q, Jakli A (2003) Nematic anisotropic liquid-crystal gels-self-assembled nanocomposites with high electromechanical reponse. Adv Funct Mater 13 525... 

Grating Formation in Photosensitive Self-Assembled Liquid Crystal Gels... 

Tong X, Zhao Y. 2003. Self assembled cholesteric liquid crystal gels for electro optical switching. J Mater Chem 13 1491 1495. 

Zhao Y, Tong X. 2003. Light induced reorganization in self assembled liquid crystal gels electrically switchable diffraction gratings. Adv Mater 15 1431 1435. 

Ordering of Polypeptides in Liquid Crystals, Gels and Micelles... 

Phase behavior experiments should be performed to identify surfactants with high contaminant solubilization, fast coalescence rates to classical microemulsions and minimal liquid crystal/gel/ macroemulsion forming tendencies over the expected range of conditions of temperature, electrolyte, surfactant, cosolvent and contaminant concentrations. The viscosity of both the aqueous surfactant solution that is injected and the microemulsion that forms when it mixes with and solubilizes the NAPL should be low, i.e. not much greater than the corresponding water (or polymer solution if polymer is added to the water). 

Y. H. Lin, H. Ren, S. Gauza, et al.. Reflective direct-view displays using dye-doped dual-frequency liquid crystal gel, J. Display Technology, 1, 230 (2005). 

H. Ren, Y. H. Lin, and S. T. Wu, Polarization-independent and fast-response phase modulators using double-layered liquid crystal gels, Appl. Phys. Lett. 88, 061123 (2006). 

Li JJ, Stannarius R, ToDcsdorf C, Zentel R (2003) Hydrogen bonded ferroelectric liquid crystal gels in fieely suspended film geometry. Phys Chem Chem Phys 5(5) 916-923. doi 10.1039/b205210e... 

Valve-Less Rectification Pumps, Figure 22 An example of a micro-pump using the principle from Fig. 18 and generation of the flow wave by alternative suction Into the nozzles on both sides of the channel. Nozzles belonging to on phase are on the same side of the channel. Alternating flow Is generated by displacement due to volume of a liquid crystal gel exposed to an electrostatic field... 

Key words Theory - phase separation - polymers - liquid crystals - gels... 

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