Collapse in a Poor Solvent

It has already been remarked that the free energy described in Eqs. (6.21)-(6.41) is for a single polyelectrolyte chain in a dilute solution, and it is valid for concentrations of salt not too high (so that lB,i.e.,Cg for a monovalent salt). It is valid, 

In order to quantify the solvent quality of the uncharged polyvinylpyridine (PVP) the expansion factor a = and the second virial coefficient A2 were measured 

It must be noted that the theory presented above predicts a first-order coil-globule transition for the chains if the excluded volume parameter w is smaller than a certain threshold value and further provided that the three-body interaction parameter W3 is also smaller than a critical value. The strength of the three-body interaction parameter pertinent to our analysis is substantially lower than the critical value (contrast this 

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