Detail of "39777-26-9"

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Absolute measurement of the critical behavior of the smectic elastic constant of bilayer and monolayer smectic-A liquid crystals on approaching the transition to the nematic phase

Absolute measurement of the critical behavior of the smectic elastic constant of bilayer and monolayer smectic-A liquid crystals on approaching the transition to the nematic phase. Fisch, M. R.; Pershan, P. S.; Sorensen, L. B. (Div. Appl. Sci. 61519-05-9 and 39777-26-9 are cas registry numbers. These chemicals are also mentioned in this article., Harvard Univ., Cambridge, MA 02138, USA). Phys. Rev. A, 29(5), 2741-50 (English) 1984. CODEN: PLRAAN. ISSN: 0556-2791. DOCUMENT TYPE: Journal CA Section: 75 (Crystallography and Liquid Crystals) A new technique which provides an abs. measurement of the smectic elastic const. B is presented. This technique measures second sound on samples whose top surface is an air-liq. crystal interface. The free surface of the sample is elec. driven and the resulting surface displacements are measured with an optical heterodyne technique. The smectic elastic const. was obtained from the spectrum of the scattered light which was detd. by the bulk second-sound modes. Two bilayer and 2 monolayer smectic-A liq. crystals were studied. Near the smectic-A-to-nematic phase transition the data can be described by a simple power law B = B1(T - TNA)f. However, the resulting crit. exponents f are not universal. In addn., the B1 values for bilayer smectics are considerably smaller than the values for the monolayer smectics. .

EPR study of the microscopic structure of binary mixtures of liquid crystals

EPR study of the microscopic structure of binary mixtures of liquid crystals. Barbarin, F.; Chausse, J. P.; Crouzeix, M.; Germain, J. P. (Lab. Electron. Resonance Magnetique, Univ. Clermont II, Aubiere 63170, Fr.). Mol. Cryst. Liq. Cryst., 101(1-2), 63-75 (French) 1983. CODEN: MCLCA5. ISSN: 0026-8941. DOCUMENT TYPE: Journal CA Section: 75 (Crystallography and Liquid Crystals) Section cross-reference(s): 77 The microscopic structure of thermotropic liq. crystals was studied. The behavior of arom. cores and aliph. chains was analyzed when defects were introduced in the mesophase as follows: to a liq. crystal having long aliph. chains (N-(p-butoxybenzylidene)-p-octylaniline; 40.8) was added one having shorter chains (N-(p-butoxybenzylidene); 40.2). An ESR study was performed using 2 nitroxide probes: in smectic phases the 1st one is localized close to the arom. cores while the other remains in the vicinity of aliph. chains. In the nematic phases, when concn. in 40.2 varies, the orientational potential is homogeneous because of the mol. translational diffusion. 29743-15-5 and 39777-26-9 which are cas registry numbers of chemicals are mentioned. For high ordered smectic phases (SB) the potential does not depend on the concn. of 40.2 while introducing defects close to the aliph. chains make the corresponding potential vary in a significant manner. In the SB phase the effect obsd. by ESR (decrease of the order parameter of probe II) is more significant than the splitting variation previously obsd. by D magnetic resonance. These results are consistent with a "partial rigidity" of aliph. chains (interpenetrating structure of layers, intrinsic rigidity, etc.), limiting the new possible conformations in the mixt. and with a localization of the probes corresponding to a low orientational potential (the "aliph. d. defects"). .