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

摘要

Low-rate dynamic contact angles of 14 liquids on a polystyrene-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. #gamma#_(lv)cos#theta# depends only on #gamma#_(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 #gamma#_(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.