Anomalies in light scattering from polyelectrolyte in semi-dilute solution region

Some anomalies in light scattering from polyelectrolyte in semi-dilute solution have been investigated and compared with those observed in high-molecular-weight neutral polymer solutions. Three anomalous in behavior were found&# (a) the c/R vs. sin(θ/2) curve was convex upward at a lower angle θ, (b) the c/R vs. c curve was convex upward, and (c) the Z vs. c curve exhibited a minimum. R is the reduced scattering intensity at the scattering angle θ, c the polymer concentration, and Z the dissymmetry ratio. Further, it has been pointed out that the plot of logarithm of correlation length ξ against logarithm of concentration c changes its slope at a polymer concentration at which R vs. c curve shows a maximum, i.e., at the critical polymer concentration. In the polymer concentration range above the critical point, lumps of molecules are more certain to exist rather than microgels which are conventionally regarded as the origin of the anomalies.