Athermal mixture chemical potentials

Figure 4 Chemical potentials of an athermal mixture with r2 = 4.

Finally we may observe that we have defined perfect solutions through equation (20.1) for the chemical potentials, and from this we have established the properties discussed in this paragraph. Conversely, for a solution to be perfect, all these properties must be satisfied simultaneously. Thus it is not sufficient that the mixture can be made without heat effect, and without change in volume. The entropy of mixing must also have the form (20.17). Indeed later on we shall discuss solutions (athermal solutions) for which the deviations from ideality arise entirely from the entropy term. 

We will briefly discuss the molecular dynamics results obtained for two systems—protein-like and random-block copolymer melts— described by a Yukawa-type potential with (i) attractive A-A interactions (saa < 0, bb = sab = 0) and with (ii) short-range repulsive interactions between unlike units (sab > 0, aa = bb = 0). The mixtures contain a large number of different components, i.e., different chemical sequences. Each system is in a randomly mixing state at the athermal condition (eap = 0). As the attractive (repulsive) interactions increase, i.e., the temperature decreases, the systems relax to new equilibrium morphologies. 

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