Photoinduced switching in self-assembled multilayers of azobenzene-containing ionene polycations and anionic polyelectrolytes

Ultrathin molecular assemblies of new ionene polysoaps bearing azobenzene units in the main chain and anionic polyelectrolytes have been prepared upon electrostatic layer-by-layer adsorption on charged substrates. Ionenes could be adsorbed in the trans- and cis-rich state of their azobenzene units. Use of cis-rich polymer was found to be advantageous because up to three times more material could be adsorbed per dipping cycle as from the solution of the trans polymer. Alternate irradiation with UV (<370 nm) and visible (>450 nm) light allowed to switch between the trans isomer and the cis-rich photostationary state. Photoconversion of ionenes in multilayers is lower than in solution, but higher than for multilayers of azobenzene bolaamphiphiles reported recently.