Nematic Phase transitions in Mixtures of Thin and Thick Colloidal Rods
UNDER CONSTRUCTION -- Original Entry by Holly McIlwee, AP225 Fall 09
Nematic Phase transitions in Mixtures of Thin and Thick Colloidal Rods. K. R. Purdy, S. Varga, A. Galindo, G. Jackson, and S. Fraden. Phys. Rev. Lett. 94, 057801 (2005).
Fraden et al. report experimental measurements of the phase behavior of mixtures of thin (charged semiflexible fd virus) and thick (fd-PEG, fd virus covalently coated with polyethylene glycol) rods with diameter ratio varying from 3.7 to 1.1. The phase diagrams of the rod mixtures reveal isotropic-nematic, isotropic-nematic- nematic, and nematic-nematic coexisting phases with increasing concentration. In stark contrast to predictions from earlier theoretical work, a nematic-nematic coexistence region bound by a lower critical point is observed. Moreover, it is shown that a rescaled Onsager-type theory for binary hard-rod mixtures qualitatively describes the observed phase behavior.