Measurement of the full refractive index tensor in sheared liquid-crystalline polymer solutions

The full refractive index tensor of sheared liquid crystalline solutions of poly(γ-benzylglutamate) in m-cresol has been measured using a combination of optical techniques. At all shear rates studied, the average molecular orientation direction is within 2 deg of the flow direction. In the low shear rate tumbling regime, the orientation angle is positive, in agreement with the Larson-Doi polydomain model. As shear rate is increased, the orientation angle changes sign, consistent with a transition from tumbling to flow alignment, as predicted by the Doi molecular model