Troubleshooting of surface free energy acid-base theory applied to solid surfaces: The case of Good, van Oss and Chaudhury theory

The Good-van Oss-Chaudhury acid-base theory applied to the calculation of solid surface free energy components has a mathematical nucleus whose correct use has important effects on its results; in particular, one needs to develop an appropriate reference scale to compare the acidic and basic components. In the present paper the mathematical properties of the equation system expressing the theory are fully analysed and their consequences from both theoretical and practical points of view are shown. A critical analysis of the most common literature misunderstandings about the theory is performed and some proposals for the choice of a new and proper scale of acid-base strength are made.