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

Law-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 t hat 9 liquids yield non-constant contact angles, and/or dissolve the polyme r. 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 tensio n, i.e. gamma(lv)cos theta depends only on gamma(lv) for a given solid surf ace (or solid surface tension). This contact angle pattern is in harmony wi th those from other inert and non-inert (polar and non-polar) surfaces. The solid-vapour surface tension calculated from the equation-of-state approac h 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 ang les of the 5 liquids in Laboratory 1, and gamma(sv) = 29.9 mJ/m(2) from mea surements with two liquids in Laboratory 2. The difference is essentially d ue to actual physical differences between the polymer films prepared in the two laboratories.