ADSORPTION OF ALKYLTRIMETHYLAMMONIUM BROMIDE AND ALKYLPYRIDINIUM CHLORIDE SURFACTANT SERIES ON POLYTETRAFLUOROETHYLENE POWDER

The adsorption and zeta potential of three different alkyltrimethylamm onium bromides, CTAB, TTAB, and DTAB, and two alkylpyridinium chloride s, CPC and DPC, on a PTFE surface were studied. Adsorption isotherms h aving characteristics similar to those of two plateau regions were obs erved for all these surfactants. In the case of alkyltrimethylammonium bromide, there is a considerable effect of chain length which could b e attributed to the arrangement of surfactant molecules being tilted a way from the perpendicular. In the case of alkylpyridinium surfactants , an insignificant effect of chain length is due to a predominantly pe rpendicular arrangement. The thermodynamics of hemimicellization has b een described by evaluating nh, as well as free energy of hemimicelliz ation. (C) 1996 Academic Press, Inc.