Flow birefringence in longitudinal and shear flows of polyelectrolyte solutions

The dynamics of macromolecules in semidilute solutions of isotactic poly(2-vinylpyridine) in aqueous hydrochloric acid solutions of different concentrations and bromoforms was studied by the method of optical birefringence in longitudinal (elongation) and shear flows. The longitudinal hydrodynamic flow field produces a stronger action upon macromolecular coils (up to their complete unfolding) than does the shear flow field. Contribution of the kinetic rigidity of charged polymer chains to the dynamics of macromolecules in solutions in the hydrodynamic fields of both types was estimated. The deforming influence of the flow upon macromolecules decreases with increasing polymer solution concentration, which is interpreted as evidence of the effect of unfolded chains on the hydrodynamic flow field structure.