D. Y. Kwok

Low-rate Dynamic Contact Angles on Poly(methyl methacrylate/n-butyl methacrylate) and the Determination of Solid Surface Tensions

Abstract Low-rate dynamic contact angles of 12 liquids on a poly(methyl methacrylate/n-butyl methacrylate) P(MMA/nBMA) copolymer are measured by an automated axisymmetric drop shape analysis-profile (ADSA-P). It is found that 6 liquids yield non-constant contact angles, and/or dissolve the polymer on contact. From the experimental contact angles of the remaining 6 liquids, it is found that the liquid- vapour surface tension times the cosine of the contact angle changes smoothly with the liquid-vapour surface tension, i.e., γiv cos θ depends only on γiv for a given solid surface (or solid surface tension). This contact angle pattern is in harmony with those from other inert and noninert (polar and non-polar) surfaces [34-42, 51 -53]. The solid-vapour surface tension calculated from the equation-of-state approach for solid -liquid interfacial tensions [14] is found to be 34.4 mJ/m2, with a 95% confidence limit of \pm 0.8mJ/m2, from the experimental contact angles of the 6 liquids.

Low-rate dynamic contact angles on poly[styrene-alt-(hexyl/10-carboxydecyl(90/10)maleimide)] and the determination of solid surface tensions

Low-rate dynamic contact angles of 14 liquids on a poly[styrene-alt-(hexyl/10-carboxydecyl(90/10)maleimide)] P[S-(H/CM)] were measured by means of an automated axisymmetric drop shape analysis-profile (ADSA-P). It was found that 9 liquids yield non-constant contact angles, and/or dissolve the polymer. From the experimental contact angles of the remaining 5 liquids, it was found that the product of the liquid-vapour surface tension and the cosine of the contact angle changes smoothly with the liquid-vapour surface tension, i.e. γ lv cosθ depends only on γ lv for a given solid surface (or solid surface tension). This contact angle pattern is in harmony with those from other inert and non-inert (polar and non-polar) surfaces. The solid-vapour surface tension calculated from the equation-of-state approach for solid-liquid interfacial tensions was found to be 31.0 mJ/m 2 , with a 95% confidence limit of ±0.6 mJ/m 2 from the experimental contact angles of the 5 liquids in Laboratory 1, and γ sv = 29.9 mJ/m 2 from measurements with two liquids in Laboratory 2. The difference is essentially due to actual physical differences between the polymer films prepared in the two laboratories.

Low-rate dynamic contact angles on poly(methyl methacrylate/ethyl methacrylate, 30/70) and the determination of solid surface tensions

Low-rate dynamic contact angles of 12 liquids on a poly(methyl methacrylate/ethyl methacrylate, 30/70) P(MMA/EMA, 30/70) copolymer were measured by an automated axisymmetric drop shape analysis-profile (ADSA-P). It was found that five liquids yield nonconstant contact angles, and/or dissolve the polymer on contact. From the experimental contact angles of the remaining seven liquids, it is found that the liquid-vapor surface tension times cosine of the contact angle changes smoothly with the liquid-vapor surface tension (i.e., γlυ cos θ depends only on γlυ for a given solid surface or solid surface tension). This contact angle pattern is in harmony with those from other methacrylate polymer surfaces previously studied. 45,50 The solid-vapor surface tension calculated from the equation-of-state approach for solid-liquid interfacial tensions 14 is found to be 35.1 mJ/m 2 , with a 95% confidence limit of ± 0.3 mJ/m 2 , from the experimental contact angles of the seven liquids.