Phase transitions in lyotropic colloidal and polymer liquid crystals

Abstract

An overview is given of theory and experiments on liquid crystal phases which appear in solutions of elongated colloidal particles or stiff polymers. The Onsager (1949) virial theory for the isotropic-nematic transition of thin rodlike particles is treated comprehensively along with extensions to polydisperse solutions and soft interactions. Computer simulations of liquid crystal phases in hard particle fluids are summarized and used to assess the quality of statistical mechanical theories for stiff particles at higher volume fraction-like the inclusion of higher virial coefficients, y-expansion, scaled particle theory and density functional theory. Both computer simulations and density functional theory indicate formation of more highly ordered smectic phases. The range of experimental applicability is strongly widened by the extension of the virial theory to wormlike chains by Khokhlov andSemenov (1981, 1982). Finally, experimental results for a number of carefully studied, charged and uncharged colloids and polymers are summarized and compared to theoretical results. In many cases the agreement is semi-quantitative.

Simulation of random packing of binary sphere mixtures by mechanical contraction

“…For monodisperse spherocylinders, the orientationally average excluded volume E is proportional to the aspect ratio a for large a [22,23]. In the same limit of a, it has been shown by simulation [10] that the packing volume fraction is proportional to a, and hence E:…”

Nematic-disordered phase transition in systems of long rigid rods on two-dimensional lattices

“…The study of the ordering transition in a system of long rigid rods in solution with only excluded volume interaction has a long history, starting with Onsager's proof that beyond a critical density, a solution of thin cylindrical rods would undergo a transition to an orientationally ordered state [1][2][3][4]. In two dimensional continuum space, when the rods may orient in any direction, the continuous rotational symmetry remains unbroken at any density.…”

Semiconductor Nanorod Liquid Crystals

“…The poor monodispersity of these colloidal rods also prevents the quantitative comparison between experiments and theories ( 14).…”