DETERMINATION OF CONTACT ANGLES AND SOLID-SURFACE TENSIONS OF POLY(4-X-STYRENE) FILMS

Low-rate dynamic contact angles of water, glycerol and methylene iodid e on polystyrene and poly(4-(X = CH3, (CH3)(3), Cl, OH)-styrene) films were measured by axisymmetric drop shape analysis-profile (ADSA-P) fo r sessile drops. It was found that glycerol in the case of poly(4-chlo rostyrene) and methylene iodide on all investigated surfaces did not y ield constant contact angles: dissolving of the polymer during the con tact with the liquid, penetration effects and stick/slip behavior were found. Water and glycerol yielded meaningful constant contact angles (except for glycerol on poly(4-chlorostyrene), for which we used forma mide additionally). From these meaningful contact angles the solid sur face tensions of the modified polymers were calculated using the equat ion of state approach [6]. The following values of gamma(sv) were dete rmined: polystyrene gamma(sv) = 28.3 mJ/m(2), poly(4-methylstyrene) ga mma(sv) = 25.8 mJ/m(2), poly(4-tert-butylstyrene) gamma(sv) = 22.0 mJ/ m(2), poly(4-hydroxystyrene) gamma(sv) = 44.1 mJ/m(2), poly(4-chlorost yrene) gamma(sv) = 27.2 mJ/m(2).