LOW-RATE DYNAMIC CONTACT ANGLES ON POLY(N-BUTYL METHACRYLATE) AND THEDETERMINATION OF SOLID-SURFACE TENSIONS

Low-rate dynamic contact angles of 22 liquids on a poly(n-butyl methac rylate) (PnBMA) polymer are measured by an automated axisymmetric drop shape analysis-profile (ADSA-P). It is found that 16 liquids yielded non-constant contact angles, and/or dissolved the polymer on contact. From the experimental contact angles of the remaining 6 liquids, it is found that the liquid-vapor surface tension times cosine of the conta ct angle changes smoothly with the liquid-vapor surface tension, i.e. gamma(1v) cos theta depends only on gamma(1v) for a given solid surfac e (or solid surface tension). This contact angle pattern is in harmony with those from other inert and non-inert (polar and non-polar) surfa ces [34-37, 45-47]. The solid-vapor surface tension calculated from th e equation-of-state approach for solid-liquid interfacial tensions [14 ] is found to be 28.8 mJ/m(2), with a 95% confidence limit of +/-0.5 m J/m(2), from the experimental contact angles of the 6 liquids.