title: Polarization field effects at liquid-crystal-droplet-polymer interfaces.
abstract: The influence of confinement (droplet size) and liquid crystal orientational order (smectic-A and nematic) on the interfacial polarization field effects [Maxwell-Wagner-Sillars (MWS) effect] existing in liquid-crystal-droplets-polymer systems is investigated by broadband dielectric spectroscopy and a forward transmittance measurement technique. A relaxation process observed in the low frequency domain of the dielectric spectrum has been associated with a MWS effect for both micron-size and submicron-size droplets. Using electro-optical measurements and numerical simulations of the field inside droplets, it is shown that a depolarization field takes place in the same frequency range as that determined by dielectric spectroscopy. Differential scanning calorimetry measurements allowed to estimate the phase-separated liquid crystal [4,4'-octylcyanobiphenyl (8CB)] fraction, which was found in the range of 55% for both micron-size and submicron-size droplets. X-ray diffraction experiments showed that smectic 8CB confined to micron-size cavities adopt bulklike properties, i.e., a partial bilayer structure, whereas in submicron-size droplets the layer spacing of the smectic phase is increased due to the strong bending deformations induced by the high curvature of the cavity walls.
authors.affiliation: Laboratoire de Thermophysique de la Matière Condensée, UMR CNRS 8024, MREI, Université du Littoral-Côte d'Opale, 59140 Dunkerque, France.
authors.forename: Mourad
authors.initials: M
authors.lastname: Boussoualem
authors.forename: Mimoun
authors.initials: M
authors.lastname: Ismaili
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Lamonier
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Buisine
authors.forename: Frédérick
authors.initials: F
authors.lastname: Roussel