8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P3.13Manipulating gibbsite liquid crystals in an externalelectric fieldAnke Leferink op Reinink, 1 Bonny Kuipers, 1 Dima Byelov, 1 Andrei Petukhov, 1Gert-Jan Vroege, 1 and Henk Lekkerkerker 11 Utrecht University, Van ’t Hoff Laboratory for Physical and Colloid Chemistry,Hugo R. Kruytbuilding, Padualaan 8 3584CH, Utrecht, NetherlandsResearch on colloidal liquid crystals based on anisometric mineral particles has witnessed aspectacular growth in the last decade enabled by the development of novel particles both ofnatural and synthetic origin. The remarkable electrical, optical and magnetic properties of theseparticles together with their excellent thermal stability has led to a variety of new phenomena bothin equilibrium and in external fields [1, 2]. In this research both the isotropic and the differentliquid crystal phases (nematic, columnar) of platelike colloidal gibbsite are studied in a highfrequency (40 kHz) alternating electric field. Small angle x-ray scattering experiments (SAXS)revealed that already in a moderate field in the isotropic phase the particles align significantlywithin seconds. The orientational order parameter increases with increasing volume fraction.The SAXS-measurements are complemented with polarization microscopy to obtain detailedinformation on the orientations of the liquid crystals. The role of the size of the gibbsite platelets(varying from 200 to 750 nm in diameter) in both sterically and charged-stabilized systems willbe discussed.[1] P. Davidson, J. Gabriel, Curr. Opin. Colloid Interface Sci. , 9, 377 (2005).[2] E. van den Pol, A. Petukhov, D. Thies-Weesie, D. Byelov, G. Vroege, PRL. , 103, 258301(2009).13