Influence of spacer length and rigidity on properties of phosphonium polymers and on their supramolecular assembly with a conjugated polyelectrolyte

Abstract

A series of seven cationic polymers have been prepared wherein the length of spacer between charge-bearing sites has been varied. Thermal stability of the polymers was characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The length of spacer has obvious effect on thermal stability as well as on the extent of crystallinity as revealed by X-ray powder diffraction. The cationic polymers were tested for their ability to form supramolecularly-assembled films with an anionic polythiophene derivative by a layer-by-layer (LbL) deposition process. Film growth was followed by spectroscopic techniques and surface morphologies were examined by atomic force microscopy (AFM). Interesting dependence of film morphology and composition was observed depending on whether an even- or odd-number of methylene spacers was present between charge-bearing sites.