Membrane Composites Derived from Porous versus NonPorous Surfactants: Evidence for Uniqueness of Calix[6]arene-Based Surfactants

In this paper we provide evidence for uniqueness of calix[6]arene surfactants as building blocks for the construction of permeation-selective composites. Specifically, we show that membranes made from poly[1-(trimethylsilyl)-1-propyne] (PTMSP) plus multilayers of calix[6]arene I exhibit significant permeation selectivity toward He and N{sub 2}, but that those based on arachidic acid (AA), cadmium arachidate (AA/Cd{sup 2+}), a polyion complex of AA plus poly(ethyleneimine) (AA-PEI), and stearamide oxime (SA) show no permeation selectivity and no alteration in the barrier properties of the support. We also report results of surface analyses of PTMSP/I and PTMSP/SA by X-ray photoelectron spectroscopy (XPS) that offer insight into the origin of these striking differences. 40 refs., 2 figs., 1 tab.