Critical phenomena of chain-molecule solutions

Abstract: A model of Landau-Ginsburg-Wilson type is used to describe the dependence of the critical amplitude (associated with coexistence curve, or correlation length, or Susceptibility) on molar mass for chain-molecule solutions of both small molecules and polymers. Experimental methods for measurements of the critical volume fraction, coexistence curve, and turbidity are discussed. Some experimental results are summarized and compared with the theory, which shows that the theory is satisfied within experimental uncertainties. INTRODIJCTION It is well known that polymer solutions near their critical consolute points exhibit behaviour similar to those of binary mixtures of small molecules, pure fluids, and ferromagnets in the critical regions. They fall into the same universality class of the 3-D king model. Like the other numbers of this class, the various thermodynamic properties of critical polymer solutions show the power-law dependence on the distance in temperature from the critical point. In addition, the amplitudes of the power-law expressions are dependent on the number of the units in the polymer, or the molar mass of the polymer (ref. 1- ref.5). These can be described as the general forms