Variation of the gyration swelling with concentration

In 1974, a team at Saclay20 measured the radii of gyration Rhz of polystyrene chains in solution in CS2 by neutron scattering at room temperature, for different solute concentrations. Let us briefly describe the experiment. The 

some comments on this table. The Z -average of the square radius of gyration in the limit of zero concentration, Ro.z, is measured by the usual scattering technique (Section 1.3.1) the sample of type 1 used here, is made exclusively of deuterated chains. This sample, being relatively polydisperse, we shall choose the monodisperse system of molecular mass Mw as a reference. The square radius of gyration of the reference chain is 

The basic quantity Rg,z for sample 2 could not be determined by neutron scattering here, the observation window (15.1.23) is not adapted to the measurement of such a big radius. On the other hand, in semi-dilute solution, the swelling is less important and the quantities Rq,z(p) are accessible to experimentation. 

In Table 15.10, we find the values of the square radius of gyration, FG-Z(p), for various overlap ratios p/p. A distinct decrease of Rg,z(p) is observed when this ratio increases. With which variation law, may we compare this result A formula, analogous to (13.2.15) 

Formula (15.4.6), validly describes the variations of Rq with respect to CX4 (d = 3), in the asymptotic regime z 1. However, the interaction parameter z here takes a value which is lower than the values corresponding to that regime (see Table 15.9), Also, since K(oo) = 0.952 [see (13.1.63)], the quantities CX3 and X2 are given by the relations 

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