LANGMUIR-BLODGETT-FILMS COMPOSED OF CATIONIC AMPHIPHILE COMPLEXED WITH TRIBLOCK POLYANION WITH A BIOMEMBRANE-MIMICKING, CHANNEL-LIKE PATHWAY FOR TRANSPORTING IONS

Novel polyion-complexed Langmuir-Blodgett (LB) films having a channellike pathway for transporting ions were prepared from the polyion-complexed monolayers composed of newly synthesized triblock polyanions (poly(styrene-p-sulfonate)-block-poly(methacrylic acid)-block-poly(styrene-p-sulfonate) (S(n)M(m)S(n))) and a double-chain, cationic amphiphile. The cationic amphiphile was found to complex preferentially with poly(styrene-p-sulfonate) segments and not with poly(methacrylic acid) segments at low pH. The polyion complexes formed stable surface monolayers, which were affected by pH in the subphase. The permeability of the hydrophilic permeants (KCl and tetramethylammonium bromide) across the LB films of those monolayers (10 layers) was reversibly switched on and off by pH change as a result of the conformational change of the poly(methacrylic acid) segments, while the permeability of the hydrophobic permeant (hexyltrimethylammonium bromide) with long alkyl chain was controlled by the phase transition of the component monolayers rather than by pH change.