SOLUBILIZATION AND ADSOLUBILIZATION OF PYRROLE BY SODIUM DODECYL-SULFATE - POLYPYRROLE FORMATION ON ALUMINA SURFACES

The effect of added sodium chloride (0-0.5 M) on the solubilization behavior of pyrrole in micellar sodium dodecyl sulfate (SDS) solution was determined using semiequilibrium dialysis. The highest solubilization constant, K, was 2.85 M(-1) in the absence of salt. The minimum K observed was 1.95 M(-1) at 0.1 M salt. Static SDS adsorption isotherms and pyrrole adsolubilization on alumina powder were obtained with varying concentrations of pyrrole (0-0.016 M) and sodium chloride (0-1.5 M). Pyrrole was found to decrease surfactant adsorption in contrast to alcohols, alkanes, and aromatic hydrocarbons. Pyrrole adsolubilization values ranged from 7 to 25 mu mol/g of alumina. A particular pyrrole adsolubilization value can be attained with a lower equilibrium SDS concentration by adding salt. The interfacial concentration of pyrrole is increased by the addition of salt, enabling the use of admicellar-assisted polymerization with ammonium persulfate to produce thin, well-connected films of polypyrrole salts on alumina plates, demonstrating the applicability of the technique to monomers with moderate water solubility. The resistance of the film is comparable to much thicker films produced in the absence of salt and surfactant. No him formation was observed using solutions of SDS without added salt.