CHARGE TRAPPING IN POLY(3,4-DIPHENYLPYRROLE) AND RELEASE BY TRACE HALOCARBONS IN WATER

The sorption of trace organics from aqueous solution into the substitu ted pyrrole polymer, poly(3,4-diphenylpyrrole), has been investigated with cyclic voltammetry, UV-visible spectroelectrochemistry, flow-inje ction amperometry, and electrochemical quartz crystal gravimetry (EQCM ). EQCM experiments revealed that the addition of the phenyl substitue nts improves the sorption capacity for dichloromethane by an order of magnitude over poly(N-methylpyrrole). Cyclic voltammetry showed no red ox activity for poly(3,4-diphenylpyrrole) in pure aqueous electrolyte. When trace amounts of halocarbons are present in aqueous solution, ho wever, the redox waves of poly(3,4-diphenylpyrrole) are observed and a re well-behaved. This behavior was compared to a composite film consis ting of poly(3,4-diphenylpyrrole) doped with the polyelectrolyte anion , poly(styrenesulfonate). The composite polymer displays ''normal'' vo ltammetric response in aqueous electrolyte with the current response o nly moderately increasing in the presence of trace halocarbons. The di fference in the voltammetric behavior of the two polymers is discussed in terms of the relative hydrophobicities of the oxidized and reduced forms of each film.