Other determination b osmotic two-body parameter

We can also determine the value of interaction b from the second virial coefficient A2, a basic quantity associated with osmotic pressure as well as radiation scattering. Hence, for a monodisperse solute of molecular mass M, the 

When we express this pressure as a function of chain concentration C and of equivalent Brownian area S, we get, for d = 3 [see (10.8.8)], 

Substituting p = CM/ in the first equation, we obtain A2 by identification of the quadratic terms 

Introducing an explicit expression of j(z) in (15.3.6), we could determine the parameter z from A2. We would then obtain a result analogous to the one reported in Table 15.2. However, it seems more interesting to proceed in the reverse way let us determine zj(z) from observed values of the second virial coefficient. We therefore write 

The product M2A2 is a volume, comparable to the effective volume occupied by chains. It is therefore natural to compare this expression to the 3/2 power of the swelling 3E0. In such a manner, we introduce the two-body osmotic parameter g z) given by (10.8.10) 

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