Dynamics of polymer θ - solutions in the dilute - semidilute transition region

2014 Rheological and diffusional properties of a polymer theta-solution are considered on the basis of novel theoretical approach. The effect of topological constraints on the dynamics of the system in the dilutesemidilute transition region is studied. In particular it is shown that (i) the relative viscosity, ~r of the solution increases according to the law ~r ~ N1.5 (C/C* 1)6, 0 C/C* 1 ~ 1, where N is the number of links in a polymer chain, C * is the critical concentration of order of the concentration of overlapping ; (ii) the selfdiffusion constant of macromolecules, D decreases exponentially with the concentration : D ~ exp (-C/C*), 1 C/C* 1.5 ln N ; (iii) the motion of macromolecules can be described by the simple single-constant diffusion law only on very large scales q-1 > Rc (q is a characteristic wave vector), where Rc ~ N1.25a, i.e. Rc essentially exceeds the size of macromolecules, R = N1/2a. Theoretical results are compared with experimental data in detail. J. Phys. France 49 (1988) 1353-1363 AOÛT 1988, Classification Physics Abstracts 05.90 81.20S