201. Reversal of Interfacial Dipole Orientation in Polyelectrolyte Superlattices Due to Polycationic Layers
- Author
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Jeanne M. Robinson, Hsing-Lin Wang, Malkiat S. Johal, and Peter A. Chiarelli, Joanna L. Casson, and Duncan McBranch, and Jerrad B. Roberts
- Subjects
chemistry.chemical_classification ,Materials science ,Aqueous solution ,Bilayer ,Polymer ,Chromophore ,Conjugated system ,Polyelectrolyte ,Surfaces, Coatings and Films ,Dipole ,Crystallography ,chemistry ,Dendrimer ,Materials Chemistry ,Organic chemistry ,Physical and Theoretical Chemistry - Abstract
Repeated bilayers of a polycation and a polyanion were assembled by adsorption from their aqueous solutions. The polycations used were PEI (poly(ethylenimine)), PAH (poly(allylamine hydrochloride)), and generation 3.0 dendrimer (poly(propylenimine)). The polyanion was PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt]). Second harmonic generation (SHG) and UV−vis spectroscopy were used to study the structure and formation of the superlattices. The linear increase in absorbance versus the number of bilayers suggested that a uniform and consistent amount of polymer adsorbed during each deposition cycle. The observation of a second harmonic (SH) signal from the film showed that the conjugated chromophores in the PAZO polymer were aligned with a net dipole. However, the SHG signal did not continue to increase as the number of bilayers was increased. On the basis of thorough studies of the UV and SH properties for each bilayer for 10 total bilayers, we propose that t...
- Published
- 2000