title: Electroconvection in nematic liquid crystals via nanoparticle doping.
abstract: It is known that a small fraction of nanoparticles dispersed in a liquid crystal can alter the electrooptic response, completely. The present study on gold nanoparticles dispersed in 5-n-heptyl-2-(4-n-octyloxy-phenyl)-pyrimidine shows that the contrast inversion observed earlier is initiated by a change from parallel to homeotropic anchoring, thereby causing an instability, which in turn leads to the appearance of convection rolls. After rapid cooling from the isotropic phase, the nanoparticle dispersion shows a regular field-induced Fréedericksz transition, like the pure liquid crystal. The electrohydrodynamic instability is presumably an example for the behavior of (+, -) systems that was predicted by de Gennes, and only recently observed experimentally for the first time.
authors.affiliation: Department of Chemistry, Faculty of Science, University of Paderborn, Warburger Str. 100, 33098, Paderborn, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Urbanski
authors.forename: Brandy
authors.initials: B
authors.lastname: Kinkead
authors.forename: Hao
authors.initials: H
authors.lastname: Qi
authors.forename: Torsten
authors.initials: T
authors.lastname: Hegmann
authors.forename: Heinz-S
authors.initials: HS
authors.lastname: Kitzerow
mesh_terms: D006046:Gold / Q000737:chemistry; D050866:Liquid Crystals / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry
chemical_list: D011743:Pyrimidines; D006046:Gold; C030986:pyrimidine