title: Induced stabilization of columnar phases in binary mixtures of discotic liquid crystals.
abstract: Three discotic liquid-crystalline binary mixtures, characterized by their extent of bidispersity in molecular thickness, were investigated with molecular dynamics simulations. Each equimolar mixture contained A-type (thin) and B-type (thick) discogens. The temperature-dependence of the orientational order parameter reveals that A-type liquid samples produce ordered phases more readily, with the (hexagonal) columnar phase being the most structured variant. Moderately and strongly bidisperse mixtures produce globally-segregated samples for temperatures corresponding to ordered phases; the weakly bidisperse mixture displays microheterogeneities. Ordered phases in the B-type liquid are induced partially by the presence of the A-type fluid. In the moderately bidisperse mixture, order is induced through orientational frustration: a mixed prenematic-like phase precedes global segregation to yield nematic and columnar mesophases upon further cooling. In the strongly bidisperse mixture, order is induced less efficiently through a paranematic-like mechanism: a highly-ordered A-type fluid imparts order to B-type discogens found at the interface of a fully-segregated sample. This ordering effect permeates into the disordered B-type domain until nematic and columnar phases emerge upon further cooling. At sufficiently low temperatures, all samples investigated exhibit the (hexagonal) columnar mesophase.
authors.affiliation: Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Delegación Iztapalapa, México, D.F. 09340, Mexico.
authors.forename: Octavio
authors.initials: O
authors.lastname: Cienega-Cacerez
authors.affiliation: Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Delegación Iztapalapa, México, D.F. 09340, Mexico and Unidad Multidisciplinaria de Docencia e Investigación-Juriquilla, Facultad de Ciencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro 76230, Mexico.
authors.forename: Consuelo
authors.initials: C
authors.lastname: García-Alcántara
authors.affiliation: Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Delegación Iztapalapa, México, D.F. 09340, Mexico.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Moreno-Razo
authors.affiliation: Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Delegación Iztapalapa, México, D.F. 09340, Mexico.
authors.forename: Enrique
authors.initials: E
authors.lastname: Díaz-Herrera
authors.affiliation: Department of Chemistry, Delaware Valley University, 700 East Butler Avenue, Doylestown, Pennsylvania 18901, USA. Edward.Sambriski@delval.edu.
authors.forename: Edward John
authors.initials: EJ
authors.lastname: Sambriski