Variation of the gyration swelling with temperature

The square radius of gyration of a chain in semi-dilute solution (CX 1) is written as [see (15.4.6)] 

When we warm up the solution at fixed concentration C in the domain IV of the temperature-concentration diagram, the square radius 3X2 and the overlap ratio increase. The chain is then subject to two contradictory effects first the solvent quality increases, second the screening of the interaction becomes stronger. Let us first recall that the average square distance 3X2 varies in the following manner (see Chapter 12, Section 3.3.2) 

There is swelling here when the interaction (or the temperature) increases, but this swelling is less important than it is in dilute solution (Rq acfe2(2v 1), for CX3- 0). 

Richards et al.22 did the same experiment and obtained the same kind of result. This British team had in view the verification of Edwards s variation law 

After examination of the experimental reports, we can give the following explanation of these two paradoxical result. In both cases, the solute is made of a mixture of deuterated and non-deuterated polystyrene, the solvent being CS2. Concentrations and molecular masses are, for instance 21 

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