On Neglecting the Polar Nature of Halogenated Hydrocarbons in the Surface Energy Determination of Polar Solids from Contact Angle Measurements.
The generally accepted strategy of neglecting the polar nature of halogenated liquids in the surface energy determination using the Lifshitz-van der Waals/Lewis acid-base (LW/AB) approach may lead to erroneous and inconsistent results for polar solids. This was demonstrated in a simulation study carried out on monopolar basic surfaces using water, glycerol, and hypothetical liquids whose surface energy characteristics (gamma(L)(LW)=50 mJ/m(2), gamma(L)(-)=0, and gamma(L)(+)=0-1 mJ/m(2)) were chosen to approximate halogenated hydrocarbons. Neglect of the liquid polarity overestimates the LW component and underestimates the basic parameter of the solid surface energy. This effect increases rapidly with an increase in the actual (nonzero) gamma(L)(+) value of supposedly apolar liquid. Consequently, results with an appropriate level of precision can be obtained only with liquids having gamma(L)(+)<0.02 mJ/m(2). For liquids having gamma(L)(+) approximately 0.5 mJ/m(2) (diiodomethane, s-tetrabromoethane, and, probably, other halogenated hydrocarbons), neglect of the liquid polarity causes errors up to 15% in the LW component and up to 100% in the basic parameter of the solid surface energy. The quantitative trends established in the simulation study were indeed observed in an experimental study performed on the surfaces of poly(methyl methacrylate) and polystyrene using water, glycerol, and diiodomethane or s-tetrabromoethane as the test liquids. Copyright 2000 Academic Press.
Tretinnikov
ON
B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70 Prospekt F. Skariny, Minsk, Belarus, 220072