Suppression of Phase Transitions in a Confined Rodlike Liquid Crystal
2011; American Chemical Society; Volume: 5; Issue: 11 Linguagem: Inglês
10.1021/nn203448c
ISSN1936-086X
AutoresChristos Grigoriadis, Hatïce Duran, Martin Steinhart, Michael Kappl, Hans‐Jürgen Butt, George Floudas,
Tópico(s)Mesoporous Materials and Catalysis
ResumoThe 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.
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