Scaling laws for polymer solutions

In the case of polymer solutions, the solute molecules are flexible and may have a very large size in comparison to the solvent molecules. In such conditions, can we directly apply the scaling laws whose validity has been established for simple, liquid mixtures in the vicinity of the critical demixtion point Anyway, this is what has been done until now. 

When the correlation length is much larger than the size °R of the chains, we may think that the scaling laws apply in a similar way, both for simple liquid mixtures and for polymer solutions. Actually, we can always manage so that, near the critical demixtion point, the condition /°R P 1 holds, and we verify experimentally that, in the vicinity of this point, polymer solutions have a behaviour which can be represented by standard scaling laws. 

1 The demixtion curve in the vicinity of the critical point Let us consider the scaling law (16.4.1) 

The domain of values of t in which the scaling law is valid shrinks when M increases. 

Instead of measuring the temperature by introducing the variable t which has no universal character, we can use the more intrinsic variable x which was defined in Chapter 14, Section 2. 

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