title: Aspect ratio and polydispersity dependence of isotropic-nematic transition in discotic suspensions.
abstract: We demonstrate the strong dependency of the isotropic-nematic (I-N) transition of discotic suspensions on the aspect ratio (ξ = thickness/diameter) via control of the sizes of pristine ZrP crystals and subsequent exfoliation to monolayers. The size fractionation of the I-N transition facilitates the analysis of the effect of polydispersity. A systematic variation in the aspect ratio in the low aspect ratio region (0.001 < ξ < 0.01) showed that the I-N transition volume fraction increases with the aspect ratio in agreement with computer simulations. It was found that the transition volume fractions scale with aspect ratio φ_{I,N} = mξ^{1.36±0.07}, where the prefactor m strongly depends on size polydispersity for φ_{N} but does not depend on size polydispersity for φ_{I} with φ_{I} and φ_{N} being the volume fractions of the isotropic and the nematic phases on the cloud curves, respectively.
authors.affiliation: Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA.
authors.forename: Andres F
authors.initials: AF
authors.lastname: Mejia
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Chang
authors.forename: Ratna
authors.initials: R
authors.lastname: Ng
authors.forename: Min
authors.initials: M
authors.lastname: Shuai
authors.forename: M Sam
authors.initials: MS
authors.lastname: Mannan
authors.forename: Zhengdong
authors.initials: Z
authors.lastname: Cheng
mesh_terms: D016880:Anisotropy; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D050866:Liquid Crystals / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D013535:Suspensions / Q000737:chemistry*
chemical_list: D013535:Suspensions