Collect. Czech. Chem. Commun. 1999, 64, 1-12

Adsorption of Gaseous Propylamine on Films of Polypyrrole in Different Oxidation States

Vítězslav Papeža, Šárka Brodskáa, Jan Langmaiera,*, Zdeněk Sameca and Karin Potje-Kamlothb

a J. Heyrovský Institute of Physical Chemistry, Dolejškova 3, 182 23 Prague 8, Czech Republic
b Institut für Physik, Fakultät für Elektrotechnik, Universität der Bundeswehr, München, Werner-Heisenberg-Weg 39, D-85577 Neubiberg, Germany


Quartz crystal microbalance and Kelvin probe were used to investigate the interaction between propylamine (PrNH2) vapour and polypyrrole (PPy) films. The films were prepared by oxidative electropolymerization of pyrrole on a platinum electrode in acetonitrile solution. The nature of interaction is strongly influenced by the oxidation state of the film and co-adsorption of water. On the surface of the oxidized PPy, water adsorbs to form a multilayer. The work function increase of the Pt/PPy electrode exposed to both water and PrNH2 vapoures was attributed to the PrNH2 dissolution and dissociation within the water layer followed by the formatted PrNH3+ cation adsorption on the liquid surface with the alkyl group facing the gas phase. On the contrary, the water adsorption on the reduced PPy is rather weak and the work function decrease observed at the PrNH2 exposure might be connected with the neutral molecules adsorption directly on the polymer surface. The water co-adsorption is documented by a drop in the adsorption of PrNH2 upon lowering the water vapour pressure in the gas phase.

Keywords: Propylamine detection; Polypyrrole-based sensors; Quartz crystal microbalance; Kelvin probe; Electropolymerization.