Sensing properties of hybrid polymeric films obtained by sol-gel

Abstract

Hybrid nanocomposites based on siloxane sols, chitosan and poly(monomethyl itaconate) (PMMI) as organic polymer counterparts were prepared. Tetraethyl ortosilicate was used as inorganic network fort-ning reagent that was first transformed into soluble polymeric species by acid catalyzed hydrolysis and condensation reactions. The siloxane sol was then mixed with different amounts of PMMI and chitosan at room temperature to form the hybrid material. These hybrid materials could be easily cast as transparent and flexible films. Atomic force microscopy study showed that the organic components are more or less homogeneously distributed at nanometer scale. The hybrid films were used as membranes for the construction of all-solid-state type potentiometric electrodes. The ion-sensing capacity of the nanocomposite was tested for different anions and the best results were obtained for NO3-. It was concluded that the -NH3+HCOO- groups of chitosan act as anion exchanger creating a potential difference that vary with ion concentration in solution in the concentration range of 1.5(.)10(-4)-10(-2) mol/dm(3).