Some Characteristics of Lyotropic Liquid-Crystalline Mesophases

Some Characteristics of Lyotropic Liquid-Crystalline Mesophases 

Idit Amar-Yuli, Abraham Aserin, and Nissim Carti 

The present review is dedicated to the memory of Professor Kunieda Hironobu and his fundamental scientific contribution in the study of lyotropic liquid crystals. 

Various liquid-crystal structures have been observed in many amphiphilic systems, such as block copolymers in selective solvents [1, 2], membrane hpids [3], and surfactants in aqueous solution [4]. These structures have found widespread application in the preparation of mesoporous templates [5], the colloidal structure design of nanomaterials, including semiconducting assemblies [6], and the formation of micro structured polymeric gels [7] and vesicles for drug delivery [8], 

The lyotropic liquid crystals have been studied as a separate category of liquid crystals since they are mostly composed of amphiphilic molecules and water. The lyotropic liquid-crystal structures exhibit the characteristic phase sequence from normal micellar cubic (IJ to normal hexagonal (Hi), normal bicontinuous cubic (Vi), lamellar (1 ), reverse bicontinuous cubic (V2), reverse hexagonal (H2), and reverse micellar cubic (I2). These phase transitions can occur, for instance, when increasing the apolar volume fraction [9], or decreasing the polar volume fraction of the amphiphilic molecule, for example, poly(oxyethylene) chain length in nonionic poly(oxyethylene) alkyl (oleyl) or cholesteryl ether-based systems (10, 11). 

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I 4 Some Characteristics of Lyotropic Liquid-Crystalline Mesophases... 

Liquid crystals are wonderful materials. In addition to the solid crystalline and liquid phases, liquid crystals exhibit intermediate phases where they flow like liquids, yet possess some physical properties characteristic of crystals. Materials that exhibit such unusual phases are often called mesogerrs (i.e., they are mesogenic), and the various phases in which they could exist are termed mesophases. The well-known and widely studied ones are thermotropics, polymeries, and lyotrop-ics. As a function of temperatirre, or depending on the corrstituerrts, concentration, substituents, and so on, these liqirid crystals exist in many so-called mesophases— nematic, cholesteric, smectic, and ferroelectric. To understand the physical and optical properties of these materials, we will begin by looking into their constituent molecules. ... 

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