POLYCATION EFFECTS ON ELECTRONIC SPECTRA OF CONJUGATED POLYMERS IN PROGRAMMED ELECTROSTATIC ASSEMBLIES

A polysaccaride, chitosan, has been used to study polycation effects on electronic spectra of conjugated polymers in programmed electrostatic assemblies. Conjugated polyelectrolytes, poly[2-(3-thienyl)-ethanolhydroxycarbonylmethylurethane] (HPURET) and polydiacetylene from 5,7-dodecadiyn-1,12-bis-(hydroxycarbonylmethylurethane) (HP4BCMU), were assembled from aqueous solution alternately with the polycation, poly (diallydimethylammonium) chloride [PDADMAC], and with the polysaccharide cation, chitosan. Switching polycations did not significantly change the visible absorption spectra for HP4BCMU multilayers. The optical properties of the regiorandom polythiophene, HPURET, depend distinctly on the polycation and the pH of the solution, showing significant differences on visible absorption maxima of the assemblies ranging from 435 nm to 516 nm. After the assemblies were exposed to vapor of aqueous ammonia, they showed UV-vis maxima further red shifted and an enhanced emission intensity, compared to those of t...