title: Suppression of phase transitions in a confined rodlike liquid crystal.
abstract: The nematic-to-isotropic, crystal-to-nematic, and supercooled liquid-to-glass temperatures are studied in the liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) confined in self-ordered nanoporous alumina. The nematic-to-isotropic and the crystal-to-nematic transition temperatures are reduced linearly with the inverse pore diameter. The finding that the crystalline phase is completely suppressed in pores having diameters of 35 nm and below yields an estimate of the critical nucleus size. The liquid-to-glass temperature is reduced in confinement as anticipated by the model of rotational diffusion within a cavity. These results provide the pertinent phase diagram for a confined liquid crystal and are of technological relevance for the design of liquid crystal-based devices with tunable optical, thermal, and dielectric properties.
authors.affiliation: Department of Physics, University of Ioannina, 451 10 Ioannina, Greece.
authors.forename: Christos
authors.initials: C
authors.lastname: Grigoriadis
authors.forename: Hatice
authors.initials: H
authors.lastname: Duran
authors.forename: Martin
authors.initials: M
authors.lastname: Steinhart
authors.forename: Michael
authors.initials: M
authors.lastname: Kappl
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Butt
authors.forename: George
authors.initials: G
authors.lastname: Floudas
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry*; D058266:Dielectric Spectroscopy; D050866:Liquid Crystals / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D009038:Motion; D009570:Nitriles / Q000737:chemistry*; D044367:Phase Transition; D016062:Porosity; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D001713:Biphenyl Compounds; D009570:Nitriles; C433919:4-cyano-4'-pentylbiphenyl; D000537:Aluminum Oxide