Suppression of phase transitions in a confined rodlike liquid crystal.

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.

[1]  H. Butt,et al.  From heterogeneous to homogeneous nucleation of isotactic poly(propylene) confined to nanoporous alumina. , 2011, Nano letters.

[2]  T. Unruh,et al.  Vibrational and molecular dynamics of a nanoconfined liquid crystal , 2010 .

[3]  M. R. de la Fuente,et al.  Critical behaviour in liquid-crystalline phase transitions: a comparative study of 9OCB in bulk and Anopore membranes , 2010 .

[4]  Kurt Binder,et al.  Rounding of phase transitions in cylindrical pores. , 2010, Physical review letters.

[5]  A. F. Oliveira,et al.  Self-assembled Monolayers of Alkylphosphonic Acids on Aluminum Oxide Surfaces – A Theoretical Study , 2010 .

[6]  S. Varga,et al.  Phase behaviour of parallel hard rods in confinement: an Onsager theory study , 2010, Journal of physics. Condensed matter : an Institute of Physics journal.

[7]  G. Grundmeier,et al.  Stability of phosphonic acid self-assembled monolayers on amorphous and single-crystalline aluminum oxide surfaces in aqueous solution. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[8]  J. Oitmaa,et al.  Monte Carlo study of mixed-spin S = (1/2, 1) Ising ferrimagnets , 2009, Journal of physics. Condensed matter : an Institute of Physics journal.

[9]  W. Knoll,et al.  Poly(γ-benzyl-l-glutamate) Peptides Confined to Nanoporous Alumina: Pore Diameter Dependence of Self-Assembly and Segmental Dynamics , 2009 .

[10]  K. Knorr,et al.  Continuous paranematic-to-nematic ordering transitions of liquid crystals in tubular silica nanochannels. , 2008, Physical review letters.

[11]  A. Brás,et al.  Confinement and surface effects on the molecular dynamics of a nematic mixture investigated by dielectric relaxation spectroscopy. , 2008, The journal of physical chemistry. B.

[12]  M. R. de la Fuente,et al.  Influence of cylindrical submicrometer confinement on the static and dynamic properties in nonyloxycyanobiphenyl (9OCB). , 2008, The journal of physical chemistry. B.

[13]  D. Morineau,et al.  Rich polymorphism of a rod-like liquid crystal (8CB) confined in two types of unidirectional nanopores , 2008, The European physical journal. E, Soft matter.

[14]  C. Schick,et al.  Origin of glassy dynamics in a liquid crystal studied by broadband dielectric and specific heat spectroscopy. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[15]  H. Lekkerkerker,et al.  Isotropic-nematic interface and wetting in suspensions of colloidal platelets. , 2006, Physical review letters.

[16]  B. Bhushan,et al.  Alkylphosphonate modified aluminum oxide surfaces. , 2006, The journal of physical chemistry. B.

[17]  C. Glorieux,et al.  Dielectric spectroscopy of aerosil-dispersed liquid crystal embedded in Anopore membranes. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[18]  G. Lahajnar,et al.  Phase transitions in 8CB liquid crystal confined to a controlled-pore glass: Deuteron NMR and small angle X-ray scattering studies , 2004 .

[19]  D. Frenkel,et al.  Self-poisoning of crystal nuclei in hard-rod liquids , 2004 .

[20]  Ralf B. Wehrspohn,et al.  Self-ordering Regimes of Porous Alumina: The 10% Porosity Rule , 2002 .

[21]  H. Sturm,et al.  On the dynamics of surface layer in octylcyanobiphenyl-aerosil systems , 2001 .

[22]  Hideki Masuda,et al.  Self-Ordering of Cell Configuration of Anodic Porous Alumina with Large-Size Pores in Phosphoric Acid Solution , 1998 .

[23]  F. Aliev,et al.  Dielectric spectroscopy of liquid crystals in smectic, nematic, and isotropic phases confined in random porous media , 1998 .

[24]  Stanislaw Urban,et al.  PVT and dielectric measurements on 4-n-pentyl-4'-cyano-biphenyl (5CB) under high pressure , 1998, Other Conferences.

[25]  Sachiko Ono,et al.  Self‐Ordering of Cell Arrangement of Anodic Porous Alumina Formed in Sulfuric Acid Solution. , 1997 .

[26]  Kenji Fukuda,et al.  Ordered Metal Nanohole Arrays Made by a Two-Step Replication of Honeycomb Structures of Anodic Alumina , 1995, Science.

[27]  Doane,et al.  Anchoring and orientational wetting transitions of confined liquid crystals. , 1993, Physical review letters.

[28]  Iannacchione,et al.  Calorimetric study of phase transitions in confined liquid crystals. , 1992, Physical review letters.

[29]  Doane,et al.  Surface elastic and molecular-anchoring properties of nematic liquid crystals confined to cylindrical cavities. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[30]  A. Würflinger,et al.  Dielectric studies of liquid crystals under high pressure: Static permittivity and dielectric relaxation in the nematic phase of pentylcyanobiphenyl (5CB). , 1992 .

[31]  J. Moura-ramos,et al.  Molecular dynamics and macroscopic alignment properties of thermotropic liquid-crystalline side chain polymers as studied by dielectric relaxation spectroscopy , 1988 .

[32]  H. Zeller.  Dielectric Relaxation and the Glass Transition in Nematic Liquid Crystals , 1982 .

[33]  R. Pecora,et al.  Time‐correlation functions for restricted rotational diffusion , 1980 .

[34]  T. Schilling,et al.  Computer simulation study of a liquid crystal confined to a spherical cavity. , 2008, Physical review. E, Statistical, nonlinear, and soft matter physics.

[35]  M. Steinhart.  Supramolecular Organization of Polymeric Materials in Nanoporous Hard Templates , 2008 .

[36]  F. Kremer,et al.  Dielectric properties of the nematic liquid crystal 4-n-pentyl-4′-cyanobiphenyl in porous membranes , 1996 .