Treatment of Dilute Solution Data

We can now examine some of the ways of calculating the polymer dimensions from experimental data. 

An investigation of the dilute solution behavior of a polymer can provide useful infonnation about the size and shape of the eoil, the extent of polymer-solvent inter-aetion, and the molar mass. Deviations from ideahty, as we have seen in Chapter 9, 

Section 9.6, are conveniently expressed in terms of virial expansions, and when solutions are sufficiently dilute, the results can be adequately described by the terms up to the second virial coefficient Aj while neglecting higher terms. The value of Aj is a measure of polymer-solvent compatibility, as the parameter reflects the tendency of a polymer segment to exclude its neighbors from the volume it occupies. Thus, a large positive Aj indicates a good solvent for the polymer, whereas a low value (sometimes, even negative) shows that the solvent is relatively poor. The virial coefficient can be related to the Flory dilute solution parameters by 

The dependence of Aj on M can oftrai be predicted, for good solvents, by a simple equation 

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