title: Surface topography and rotational symmetry breaking.
abstract: The surface electroclinic effect, which is a rotation of the molecular director in the substrate plane proportional to an electric field E applied normal to the substrate, requires both a chiral environment and C(2) (or lower) rotational symmetry about E. The two symmetries typically are created in tandem by manipulating the surface topography, a process that conflates their effects. Here we use a pair of rubbed polymer-coated substrates in a twist geometry to obtain our main result, viz., that the strengths of two symmetries, in this case the rub-induced breaking of C(∞) rotational symmetry and chiral symmetry, can be separated and quantified. Experimentally we observe that the strength of the reduced rotational symmetry arising from the rub-induced scratches, which is proportional to the electroclinic response, scales linearly with the induced topographical rms roughness and increases with increasing rubbing strength of the polymer. Our results also suggest that the azimuthal anchoring strength coefficient is relatively insensitive to the strength of the rubbing.
authors.affiliation: Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Rajratan
authors.initials: R
authors.lastname: Basu
authors.forename: Ian R
authors.initials: IR
authors.lastname: Nemitz
authors.forename: Qingxiang
authors.initials: Q
authors.lastname: Song
authors.forename: Robert P
authors.initials: RP
authors.lastname: Lemieux
authors.forename: Charles
authors.initials: C
authors.lastname: Rosenblatt
mesh_terms: D003198:Computer Simulation; D017276:Friction; D050866:Liquid Crystals / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D013499:Surface Properties