Effect of the thickness of the hydrophobic bilayer on the helical twisting power in micellar nematic liquid crystals

Mass density measurements as a tool to distinguish between micelle size and shape in nematic and chiral nematic phases

“…The different effect of the structure of some solute molecules was discussed in terms of the pitch induced in some host phases 12,13 and by measuring the mass density. 14 In the latter case, the mass density of two chiral dopants, mandelic acid (MA) and hexahydromandelic acid (HHMA), were measured in two different host phases and it is found that the chiral phases containing MA were more dense than those containing HHMA.…”

“…Some solutes may increase the volume of the micelle but some decrease it, which is reflected in the flow properties of the phase and changing the nematic-isotropic phase transition. 10,12,13 Particularly of interest is the modification observed if the DL-amphiphile mixture of a racemic nematic phase is replaced by its L-enantiomer. Therefore, it is important to capture such changes by an easily applicable method, mass density measurements, which give us insight into the phenomena taking place in the micelle on addition of any solute.…”

Comparison of helical twisting powers of novel fluorinated amphiphilic enantiomers with their hydrogenated counterparts

“…In a recent investigation we studied the htps of a series of chiral solutes of alanine esters with C 4 , C 6 , C 8 and C 10 straight hydrocarbon chains in different host phases, possessing different bilayer thicknesses, and found that the chiral solute with C 10 exhibited the highest htp when the host bilayer was composed of C 12 hydrocarbon chain [9]. As a result of this study we came to the conclusion that, if the chain length of the chiral dopant is in the order of that of the host amphiphile, it is fitted well in the hydrophobic region of the phase and acts as a "pivot" for the chiral center that could produce the highest twisting torque.…”

“…These intrinsic N * systems may be more advantageous than the induced N * phases for the following reasons: (i) The concentration of the amphiphilic enantiomer can be varied within the isotropic (I) and lamellar (L α ) phase boundaries without causing a complication in the host phase, then it is known that most of the dopants modify the properties of the host phases, e.g. cause a transition to the I or L α phase [4,9]. (ii) They are easier to visualize than the induced N * phases which, in general, contain more components than the intrinsic N * ones, and (iii) their racemic mixtures form N phases which may be of great help to determine the phase type by the easily applicable polarizing light microscopic method.…”