Radius of gyration vs. molecular

Comparison for PMMA in the glassy state and in dilute solution, of the radius of gyration vs. the weight average molecular weight (from Frischat, GH The Physics of Non-Crystalline Solids, Transtech, Switzerland, 1977). 

Figure 5 Radius of Gyration vs Molar mass of Kynar 710. The molecular weight distributions are also shown.

The quantity K equals 4it X sin (9/2), where X is the neutron wave length and 9 is the angle of scatter. Thus, the Z-average mean square radius of gyration, R, and the polymer molecular weight, Mj, may be obtained from the slope and intercept respectively of a Zimm plot of [dZ/dn] vs. K. The values of and Rg were evaluated after appropriate subtraction of the scattering from an unlabeled polymer matrix (blank) from the samples containing different fractions of labeled molecules. 

In a plot of K c/R q) vs. sin (q/2), can be obtained from the intercept and the radius of gyration, Rg, from the slope. A multi-angle measurement provides additional information on molecular size, structure, conformation, aggregation state, etc. 

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