SYNTHESIS AND CHARACTERIZATION OF CARBOXYLIC ACID-FUNCTIONALIZED POLYPYRROLE-SILICA MICROPARTICLES

1-(2-Carboxyethyl)pyrrole has been copolymerized with pyrrole in the p resence of silica particles to produce stable colloidal dispersions of polypyrrole copolymer-silica microparticle's containing carboxylic ac id groups. These new dispersions have been extensively characterized i n terms of their particle size and chemical composition by transmissio n electron microscopy, disk centrifuge photosedimentometry, elemental microanalyses, thermogravimetry, and both FTIR and visible absorption spectroscopy. The presence of the carboxylic acid groups at the surfac e of the microparticles has been confirmed by X-ray photoelectron (XPS ) spectroscopy. Visible absorption spectroscopy studies confirmed that the optical absorbance of these carboxylic acid-functionalized polypy rrole-silica microparticles is up to 4 times higher (at a wavelength o f 400 nm) than a commercial dyed carboxylated polystyrene latex (Polym er Laboratories' SuperCarboxyl Hi-Dye) of the same solids concentratio n. Thus these conducting polymerbased microparticles are expected to h ave biomedical applications as novel ''marker'' particles in immunodia gnostic assays.