Induced smectic phases in phase diagrams of binary nematic liquid crystal mixtures

Abstract

To elucidate induced smectic A and smectic B phases in binary nematic liquid crystal mixtures, a generalized thermodynamic model has been developed in the framework of a combined Flory-Huggins free energy for isotropic mixing, Maier-Saupe free energy for orientational ordering, McMillan free energy for smectic ordering, Chandrasekhar-Clark free energy for hexagonal ordering, and phase field free energy for crystal solidification. Although nematic constituents have no smectic phase, the complexation between these constituent liquid crystal molecules in their mixture resulted in a more stable ordered phase such as smectic A or B phases. Various phase transitions of crystal-smectic, smectic-nematic, and nematic-isotropic phases have been determined by minimizing the above combined free energies with respect to each order parameter of these mesophases. By changing the strengths of anisotropic interaction and hexagonal interaction parameters, the present model captures the induced smectic A or smectic B phases of the binary nematic mixtures. Of particular importance is the fact that the calculated phase diagrams show remarkable agreement with the experimental phase diagrams of binary nematic liquid crystal mixtures involving induced smectic A or induced smectic B phase.

Mixing-Induced Anisotropic Correlations in Molecular Crystalline Systems

“…Seen in this context, it would correspond to a smectic C phase, characterized by crystalline order in one direction (here the out-of-plane direction) and orientational order of tilted molecules within the planes [17], but no crystalline in-plane order. Indeed, changes in the ordering behavior upon mixing have also been observed for liquid crystal systems [18][19][20] but we emphasize that our system is conceptually different from liquid crystalline systems, since the pure compounds show well-defined 3Dorder over a large temperature range. To the best of our knowledge the anisotropic change in the ordering behavior observed for equimolar mixtures of PEN:DIP is a previously unreported effect for mixed systems of this class of molecular compounds.…”

Asymmetric Organic–Inorganic Hybrid Giant Molecule: Hierarchical Smectic Phase Induced from POSS Nanoparticles by Addition of Nematic Liquid Crystals

“…Phase behavior of binary mesogenic mixtures involving induced smectic phase is well reported in the literature. 43,44 Guided by the references, the dual UCST envelopes develop in the intermediate concentrations, where the narrow iSm phase is encompassed by the Cr 1 + iSm and Cr 1 + Cr 2 + iSm coexistence regions. In general, the Cr 2 + iSm coexistence region appears instead of the Cr 1 + Cr 2 + iSm coexistence region, but the POSS-CB crystal (Cr 1 ) is identified over the broad composition range from the DSC, POM, and WAXD results in our system.…”

An extended Stokes–Einstein model for condensed ionic water structures with topological complexity

“…volume and area [43,44]. Based on the Flory-Huggins theory, free energy of mixing (F mix ) can be written in the following form [45][46][47],…”