Concentration fluctuation effects for dynamics of polymer solutions

Dynamics of concentration fluctuation in a semidilute polymer theta‐solution in the regime of entanglements is studied theoretically. A number of relaxation modes is predicted, the largest amplitude corresponding to a reptation mode with the time , where q is the wave vector, the static correlation length, R the size of a polymer coil. A mode with a “superlong” time N 2 q −2 is predicted for . It is shown also that fluctuations of molecular field result in a substantial decrease of macromolecular curvilinear diffusion constant. The same effect gives rise to an increase of zero‐shear viscosity of the solution; the dependence of viscosity on number of links per chain, N, is much stronger than N 3 in the regime of high N.