Interfacial tension coacervate equilibrium

That adequately liquid coacervates distributed in microscopic amounts assume the spherical shape is thus the consequence of the properties of the three-dimensional contents — the liquid nature of the coacervate —and of the two-dimensional surface — the presence of an interfacial tension coacervate/equilibrium liquid. 

We can now apply this rule to obtain a verdict concerning the relative magnitude to be expected of the interfacial tensions coacervate/equilibrium liquid in the case of the binary coacervates G + A and G -h N. Naturally the other conditions must be comparable (the same pH, the same salt content of the medium, equivalent mixing proportion of G and A or of G and N, that is to say, at their reversal of charge points). Under these comparable conditions the complex relations in the G + N coacervate are considerably greater than in the G + A coacervate on account of the so much smaller equivalent weight of N than of A (see p. 375). 

For the explanation of the properties (shape, changes of state, etc.) of a colloid body of microscopic dimensions which consists of a limited amount of coacervate surrounded by equilibrium liquid, one has in general to take into account 1. the properties of the three-dimensional contents and 2. those of the two-dimensional surface. The first mentioned properties (e.g. viscosity, composition) can be studied on coacervates in bulk and these have already been described in previous chapters (VIII and X). The properties of the two-dimensional surface are equally important. The electrophoretic charge of complex coacervates drops has already been discussed in chapter X 2e (p. 345) but for this chapter it is the interfacial tension which is especially of interest. 

For the rest the assumption made is in every way plausible since condensation is associated with separation of fresh small coacervate drops from the equilibrium liquid, that is to say with a reduction of the mutual solubility of coacervate and equilibrium liquid, in the other hand swelling goes with an increase of the mutual solubility. One can now generally expect that in the first case the interfacial tension will increase, in the second case it will decrease. 

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