Additive and nonadditive surface tension components and the interpretation of contact angles

Abstract

It is demonstrated that, while the Lifshitz-van der Waals (ylw) and the polar, Lewis acid-base ( ) surface tension components are additive, the Lewis acid-base electron-acceptor ( +) and electron-donor ( ~) surface tension parameters (which on account of the intrinsic asymmetry of their interactions are connected in a more complex manner) are not additive. Contact angle data cannot, in general, be correlated with a single surface tension property. The relation between contact angles and the three controlling parameters YgW, 7s> and § of a polar solid, S, cannot be established by means of one single equation. These three unknowns can, however, be determined by means of contact angle measurements with three different liquids L (of which two must be polar and H-bonding), which are completely characterized as to their respective ylW, Yl, and £ parameters by using a modified Young-Good-Girifalco-Fowkes equation 3 times.In view of these considerations, recent claims to have proven the applicability of a single "equation of state" are shown to be spurious. angle on a particular solid would be found to have the same surface tension. Table I shows that this is not the case. Water and glycerol form nearly the same contact angle on four of the solids. But the surface tensions of the two liquids differ by 12%, and the contact angles of the two liquids are significantly different on six other solids.Further, while glycerol spreads on flat surfaces of a gel encasing water (which could be expected), it is a curious finding that water also spreads on flat surfaces of a gel encasing glycerol (see Table II). It is not possible to explain this result by means of the equation of state.

Wettability characteristics of poly(ethylene terephthalate) films treated by atmospheric pressure plasma and ultraviolet excimer light

“…The Lifshitz-van der Waals component and the Lewis acid and base parameters were calculated from the van Oss-Chaudhury-Good equation 28 by substituting the measured contact angles of water, diiodomethane and ethylene glycol and their referential surface-free energy components. 29 …”

Wettability of Sanded and Aged Fast-growing Poplar Wood Surfaces: I. Surface Free Energy

“…The vOCG method (Van Oss et al 1988) is critical because almost all surface free energy of solids calculated by the method had a much higher   value than   value; the reason is that all the surface free energy components were determined on the assumption that the water component is    , whereas water is a stronger Lewis acid than a Lewis base. Volpe and Siboni (1997) recalculated test liquid acid-base balances, resulting in a decrease in the base component compared to the vOCG method (Van Oss et al 1988).…”

“…Volpe and Siboni (1997) recalculated test liquid acid-base balances, resulting in a decrease in the base component compared to the vOCG method (Van Oss et al 1988). The acid-base values of reference liquids used according to vOCG and DVS are list in Table 1.…”

“…There is no doubt that the surface free energy calculated from the contact angle using the Zisman method (Timmons and Zisman 1968), OWRK method (Owens and Wendt 1969), and vOCG method (Van Oss et al 1988) showed wide variations. Zisman (Timmons and Zisman 1968) himself always emphasized that the critical surface free energy is not the surface free energy, but only an empirical parameter related closely to this quantity (Baldan 2012).…”

“…Depending on the surface to be examined and the selected test liquids, several methods are available for calculation of the surface energy of a solid. The earliest studies were based on critical surface tensions (Timmons and Zisman 1968), followed by the two liquids concept of harmonic (Gardner 1996, Maldas andKamdem 1999) and geometric means (Gardner 1996;Owens and Wendt 1969), the equation of state (Neumann et al 1974), and the Lifshitz-van der Waals/acid-base theory based on three liquids (Van Oss et al 1988;Volpe and Siboni 1997;Wålinder 2002).…”