Novel Layer-by-layer Complexation Technique and Properties of the Fabricated Films

Abstract

A novel layer-by-layer complex-fabrication technique for multilayer film assembly was developed by alternatively dipping desired substrates in macromolecular ligands and Eu3+ ion solutions. A water-soluble, luminescent thiophene-based polymer, viz., poly[2,5-(3-carboxymethyl urethanyl ethyl) thiophene] (H-PURET), was prepared and used as the macromolecular ligand. Multilayer deposition was monitored using UV-visible spectroscopy by following the absorbance increase due to the deposition of the polymer layer. Multilayer thin films were characterized using infrared and fluorescence spectroscopic techniques, transmission electron microscopy (TEM), and energy-dispersive X-ray spectrometry (EDXS). The conductivity and the electroluminescence properties of the conjugated polymer−Eu3+ complex multilayer films were also measured. The observed electroluminescence intensity of conjugated polymer−metal complex multilayer film was about 2 times higher than for the conjugated polymer by itself. The approach is general in that other macroligands and metal ions may be employed.