title: Synergy between polyaniline and OMt clay mineral in Langmuir-Blodgett films for the simultaneous detection of traces of metal ions.
abstract: We report on Langmuir-Blodgett (LB) films made with emeraldine salt polyaniline (PAni-ES) and organophilic montmorillonite clay mineral (OMt), where synergy between the components was reached to yield an enhanced performance in detecting trace levels of cadmium (Cd(2+)), lead (Pb(2+)) and copper (Cu(2+)). Detection was carried out using square wave anodic stripping (SWAS) voltammetry with indium tin oxide (ITO) electrodes modified with LB films of PAni-ES/OMt nanocomposite, whose data were compared to those obtained with electrodes coated with neat PAni-ES and neat OMt LB films. The enhanced performance in the nanocomposite may be attributed to the stabilizing and ordering effect promoted by OMt in PAni-ES Langmuir films, which then led to more homogeneous LB films. According to X-ray diffraction data, the stacking of OMt layers was preserved in the LB films and therefore the PAni-ES chains did not cause clay mineral exfoliation. Instead, OMt affected the polaronic state of PAni-ES as indicated in UV-vis, Raman and FTIR spectra, also consistent with the changes observed for the Langmuir films. Taken together these results do indicate that semiconducting polymers and clay minerals may be combined for enhancing the electrical properties of nanostructures for sensing and related applications.
authors.affiliation: †Faculdade de Ciências, UNESP/POSMAT, Univ Estadual Paulista, Bauru, São Paulo, Brazil.|‡Universidade Federal de São Carlos (UFSCar), Campus Sorocaba, Sorocaba, São Paulo, Brazil.
authors.forename: Anerise
authors.initials: A
authors.lastname: de Barros
authors.affiliation: §Universidade Federal do ABC (UFABC), Santo André, São Paulo, Brazil.
authors.forename: Mariselma
authors.initials: M
authors.lastname: Ferreira
authors.affiliation: ∇Faculdade de Ciências e Tecnologia, UNESP, Univ Estadual Paulista, Presidente Prudente, São Paulo, Brazil.
authors.forename: Carlos José Leopoldo
authors.initials: CJ
authors.lastname: Constantino
authors.affiliation: ⊥Campus Experimental de Sorocaba, Univ Estadual Paulista, Sorocaba, São Paulo, Brazil.
authors.forename: José Roberto Ribeiro
authors.initials: JR
authors.lastname: Bortoleto
authors.affiliation: ‡Universidade Federal de São Carlos (UFSCar), Campus Sorocaba, Sorocaba, São Paulo, Brazil.
authors.forename: Marystela
authors.initials: M
authors.lastname: Ferreira
keywords: Langmuir−Blodgett film; electrochemical sensors; metal trace detection; organophilic montmorilonitte clay mineral; polyaniline