Layer-by-layer self-assembling of a low molecular weight organic material by different electrostatic adsorption processes

Abstract

A novel method has been reported to deposit low molecular weight organic materials by a layer-by-layer self-assembled film deposition method. A different electrostatic adsorption process has been followed to show its advantage over the conventional method. When an organic material, namely, alizarin violet, with fewer ionic groups was used as the anion for electrostatic self-assembly, the dye was found to come off the film during the subsequent polycation deposition. As an alternative approach, the dye has been anchored to the polycation via a physiabsorption process prior to deposition. By controlling the concentration ratio of the two, the combination of low molecular weight material and the polycation as a whole has been used as the polycation. The absorption spectra after each deposition showed that there was no material loss during layer depositions. The results showed that the method of anchoring low molecular weight molecules to polyions could effectively be used to deposit homogeneous layer-by-layer self-assembled films of small organic molecules in general.