van der Waals–Lifshitz forces in lyotropic polypeptide liquid crystals

Abstract

The McLachlan susceptibility theory is used to calculate the van der Waals–Lifshitz forces betwen two chiral, rodlike dielectric particles embedded in an isotropic dielectric medium. The resulting interparticle potential contains an asymmetric term in φ, the mutual dihedral angle between the major axes of the particles. The variations of the free energy of interaction with respect to the mutual orientation of the particles and the relative magnitudes of the medium and particle dielectric permittivities can explain the origin and unusual solvent dependence of the cholesteric twist exhibited by lyotropic polypeptide liquid crystals.