VISCOSITIES OF DILUTE POLYMER-SOLUTIONS IN NEMATIC LIQUIDS

A nematic fluid is characterized by five friction coefficients. When dilute polymer coils are added to the fluid, all these coefficients are modified. Three Miesowicz viscosities (measured under an aligning magnetic field) and two coupling coefficients between orientation and flow are discussed. In the calculation, elastic dumbbells are used to model the flexible polymer chains. The results are written in terms of two size parameters R// parallel and R(perpendicular) and two chain friction coefficients lambda // parallel and lambda (perpendicular) (the label parallel refers to a direction parallel to the nematic axis). This could be compared to other experiments (such as translational diffusion) which measure lambda // parallel and lambda (perpendicular) directly. They may give useful estimates of coil conformation in nematic solvents.