Electrical conductivity response of Poly(P-phenylene vinylene)/zeolite composites exposed to flammable solvents

Abstract

The development of gas sensing materials with selective and sensitive properties for volatile organic compounds (VOCs) detection had been of interest due to the industrial process pollution. One of possible sensor operating principles is the electrical conductivity response of the sensing material towards VOCs. In this work. Dope poly(p-phenylene vinylene) or dPPV was mixed with the three zeolite types: zeolite Y (NaY): mordenite (NaMOR); and 5A LTA (Na5A) to detect acetone, MEK, MIBK. methanol. and n-heptane at the vapor concentration of 30000 ppm. The effects of cation type, cation concentration, zeolite type, vapor concentration, dPPV, and cyclic interval were investigated. 80CuNaY showed the highest electrical conductivity sensitivity under acetone exposure at 30000 ppm in N₂ relative to other cation types (Ni²ˉ, Fe²ˉ, Kˉ, Naˉ, Ca²ˉ, Mg²ˉ, and Hˉ). Furthermore, with increasing cation content in NaY. the electrical conductivity sensitivity towards acetone vapor increased, especially at 80% ion exchanged. 10%, v/v of dPPV was mixed into 80CuNaY and 80CuNaMOR matrices and they were exposed to acetone, methanol, and n-heptane. dPPV_[90]80CuNaY could respond well in the polar solvents (acetone and methanol) with the minimum vapor concentrations of 5 ppm for acetone and 2 ppm for methanol while dPPV_ [90]80CuNaMOR showed the lowest detection limit of 5 ppm in a non-polar vapor (n-heptane). Overall, dPPV enhanced the electrical conductivity sensitivity of 80CuNaY and 80CuNaMOR by an order magnitude. For the cyclic interval, the electrical conductivity response decreased with increasing number of cyclic intervals towards acetone vapor due to the irreversible interaction as evidenced by FTIR and AFM techniques.