Evaluation of Molecular Interaction Parameters

The two fundamental properties of surfactants are monolayer formation at interfaces and micelle formation in solution for surfactant mixtures, the characteristic phenomena are mixed monolayer formation at interfaces (Chapter 2, Section RIG) and mixed micelle formation in solution (Chapter 3, Section VIII). The molecular interaction parameters for mixed monolayer formation by two different surfactants at an interface can be evaluated using equations 11.1 and 11.2 which are based upon the application of nonideal solution theory to the thermodynamics of the system (Rosen, 1982)  

For evaluating the molecular interaction parameters for mixed micelle formation by two different surfactants, equations 11.3 and 11.4 (Rubingh, 1979) are used. 

FIGURE 11-1 Experimental evaluation of pCT or PM. Individual surfactant 1 Individual surfactant 2 Mixture of surfactants 1 and 2 at a fixed mole fraction a in solution. Reprinted with permission from M. J. Rosen in Phenomena in Mixed Surfactant Systems, J. F. Scamehom (Ed.), ACS Symp. Series 311, American Chemical Society Washington, DC, 1986, p. 148. 

---

Based upon the same nonideal solution theory used in the evaluation of molecular interaction parameters above, the conditions for the existence of synergism in... 

---