ESTIMATING SURFACE-ENERGY VARIATIONS OF SOLIDS BY INVERSE GAS-CHROMATOGRAPHY

Characterization of surface heterogeneity in polymers and solids used with polymers is important to fully understand surface and interface p henomena in polymer systems. Inverse gas chromatography (IGC) represen ts a convenient route to the information needed. In this work, finite volumes of vapor probes were injected to scan the retention characteri stics of polymers and pigments relevant to xerographic applications. T he dispersive components of surface energies and acid-base interaction potentials were determined as functions of the vapor-probe volume for a polycarbonate, polystyrene, and a styrene/4-vinyl pyridine diblock polymer, and for inorganic and organic pigments. The dispersive compon ents of the surface energies were found to vary inversely with the inj ection volume. In the polymers the surface energies varied, typically, by about 20%, and the values at high injection volumes equalled those obtained by contact angle measurement. Larger surface energy variatio ns were obtained for pigments. Substantial energy heterogeneity of aci dic and basic interaction sites also was documented by the IGC techniq ue.