TWIST-GRAIN-BOUNDARY-A LIQUID CRYSTAL RHEOLOGY

A network of flaw lines entangled with colloidal particles has recently been discovered to increase the pliability of liquid crystals. In many cases, the dynamics of such composite systems are best described in terms of soft-glassy-rheology or the theory of rubber elasticity due to their enhanced viscoelastic features. The TGB(A) phase has a substantially higher apparent yield stress than the cholesteric (N*) phase. In TGB(A), G', the modulus of phase storage, is much greater than G", the modulus of loss. Dynamic relaxation data demonstrates that all three phases (N*, TGB(A), and smectic-C*) display stable behavior. The complex shear modulus is distributed as a G*(ω)∼ω(α) power law with an exponent of α≃0.5 in the TGB(A) phase. The temperature-dependent amplitude differences of G' and G" suggest that structural faults are responsible for the TGB(A) phase's enhanced elasticity