work of adhesion against model acidic or basic liquids (3). In the second approach, described by Good, Van Oss, and Chaudury, an acid parameter
The letter underlines the need for a reflection and a debate on and a basic parameter characteristic for each solid are calculated from the quantitative results arising from the application of current wetting measurements (4).
theories on the calculation of acid-base properties of polymer
The acid-base theory of wetting phenomena and the experimental apsurfaces from wetting measurements. To this end, published reproaches to the evaluation of acid-base properties of solid surfaces by sults on the Lewis acid-base properties of poly(methylmethacrywetting measurement are undoubtedly among the most important develop- late) (PMMA) and of poly(vinylchloride) (PVC), as evaluated ments of present-day interface science. However, experimental evidence by the application of the Fowkes (work of adhesion; Fowkes, shows that the quantitative aspects of the proposed theories are not com- F. M., in ''Surface and Interfacial Aspects of Biomedical Polypletely consolidated. In particular, the Good-Van Oss-Chaudury approach mers'' (J. D. Andrade, Ed.), Vol. 1 Chap. 9. Plenum Press, New to the evaluation of the acid (g / ) and basic (g 0 ) components of the solid York, 1985) and Good-Van Oss-Chaudury (electron donor-elecsurface free energy shows that most solid surfaces are overwhelmingly basic, with a small or negligible acid component. Does this finding reflect tron acceptor components; Good, J. R., and van Oss, C. J., in a general law of solid surfaces, as discussed by Good and Van Oss (4), ''Modern Approach to Wettability: Theory and Application'' or that the consistency of the method should be checked, as suggested by (M. E. Schrader and G. Loed, Eds.), Chap. 1. Plenum Press, New Berg (2)? The complete understanding of this point is obviously very York, 1991) approaches to interfacial energetics, are compared. important, since the description and the modeling of many phenomena The former approach indicates the basic character of PMMA and involving colloids and interfaces require the quantitative application of the acidic nature of PVC surfaces. When the components of the results arising from interfacial energetics measurement. solid surface free energy are calculated according to the Good-The aim of this letter is to drive the attention to some quantitative aspects Van Oss-Chaudury theory, both surfaces appear overwhelmingly of the proposed theories and eventually promote a debate within the commu- basic, PMMA being a stronger base than PVC. Data are compared nity of students of interfacial interactions on the quantitative evaluation of to published results on the acid-base nature of PMMA and PVC, the acid-base properties of polymer surfaces by contact angle measurement. Published works on the acid-base nature of poly(vinylchloride) (PVC) as evaluated by experiments not based on wetting measurements. and poly(methylmethacrylate) (PMMA) surfaces are taken as the starting The need for a more complete understanding of the quantitative point of this debate. The choice of PVC and PMMA is dictated by the aspects of the wetting-measurement-based approaches to Lewis following reasons: acid-base interfacial interactions is stressed.