Department of Polymer Engineering, The University of Akron, Akron, Ohio 44325, USA.
J Chem Phys. 2011 Mar 28;134(12):124508. doi: 10.1063/1.3567100.
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.
为了阐明二元各向同性向列相液晶混合物中的诱导近晶 A 相和近晶 B 相，我们在各向同性混合的 Flory-Huggins 自由能、取向有序的 Maier-Saupe 自由能、近晶有序的 McMillan 自由能、六方有序的 Chandrasekhar-Clark 自由能和晶体凝固的相场自由能的框架下，开发了一个广义热力学模型。尽管向列相组分没有近晶相，但这些液晶分子在混合物中的复合导致了更稳定的有序相，如近晶 A 相或近晶 B 相。通过最小化上述各向异性相互作用和六方相互作用参数的组合自由能，确定了晶体-近晶、近晶-向列和向列-各向同性相的各种相变。通过改变各向异性相互作用和六方相互作用参数的强度，本模型可以捕获二元向列液晶混合物中的诱导近晶 A 相或诱导近晶 B 相。特别重要的是，计算得到的相图与涉及诱导近晶 A 相或诱导近晶 B 相的二元向列液晶混合物的实验相图吻合得很好。
