The Relationship between HLB and Solubility Parameter

TABLE 11.8. Solubility Parameters for Some Common Oil Phases 

From A. F. M. Barton, CRC Handbook of Solubility Parameters and Other Cohesion Parameters, CRC Press, Boca Raton, FL, 1983, Table 9, p. 167 and Eq. 11.11. 

It should not be surprising to find some quantitative relationship between the Griffin HLB number and the Hildebrand 8, given that both concepts are related to the balance of interactions between hydrophobic tails and oil phases, and head groups and aqueous phases. For example, a study of various surfactant-solvent systems by Little led to the following relationship between 5 and HLB  

Alternatively, a polynomial regression analysis of the data in Table 11.7 produces the following expression 

Equations (11.11) and (11.12) are, of course, highly empirical relationships, and alternative methods of relating HLB and solubility parameter have been proposed. In the absence of better information, such relationships can be useful as tools for estimating the solubility parameter or HLB of a particular surfactant structure and to help in its evaluation as an emulsifier candidate. 

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