Interfacial Stabilization of Amphiphilic Viologen Monolayers Induced by Poly(styrenesulfonate)

The degree of interfacial stability of self-assembled monolayers of N-ethyl-N′-octadecylviologen (1) and N-ally-N′-octadecylviologen (2) on gold surfaces is greatly increased by exposure of the monolayer to a solution of poly(styrenesulfonate). This remarkable stabilization effect can be understood by the intercalation of the polyelectrolyte chains in the monolayer generating a surfactant-polyelectrolyte complex at the electrode surface. The stability of the complex is probably due to the favorable electrostatic interactions between the cationic viologen amphiphiles and the sulfonate groups in the polyelectrolyte chains as well as to the structural cross-linking introduced by the latter.