MODE-COUPLING THEORY OF THE ISOTROPIC-NEMATIC TRANSITION IN SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS

Using a mode coupling technique we investigate the dynamics near the isotropic-nematic transition in liquid crystalline sidechain polymers. While in mean field approximation one obtains z = 1 for the dynamical critical exponent z for the relaxation time of the order parameter, we get from mode coupling the value z = 1.5, a result which is in agreement with recent experiments done in Martinoty's group on two different classes of sidechain liquid crystalline polymers using electric and acoustic birefringence measurements. An analysis of recent measurements of the dynamic stress-optical coefficient in sidechain elastomers shows that mode coupling effects are also important in that case.