Polydiphenylamine/Zeolite Y composites and electrical conductivity response toward halogenated hydrocarbons

Abstract

Composites of polydiphenylamine (D-PDPA) and zeolite Y with H¯ as the cation (YH) was fabricated to be used as a sensing material towards halogenated solvents which are toxic towards human and environment and have been widely used as solvents in various industries. The electrical conductivity and sensitivity of the composites towards the solvents was higher than the pristine PDPA by about 1 order of magnitude. The composite possessed maximum electrical conductivity sensitivity values towards dichloromethane. but they did not respond to hexane. Generally, the sensitivity of the composites increased with increasing zeolite content and vapor concentration. In order to enhance the sensing properties of the composites. PDPA was synthesized in nanoscale (nPDPA) by emulsion polymerization and YH was modified by the dealumination process (DYH) to increase the silicon and alumina ratios. The composite of nPDPA and DYH showed a higher sensitivity when exposed to the solvents than the pristine nPDPA and zeolite. The interactions between the composite and hydrocarbon vapors were investigated by FT-IR spectroscopy and UV-Vis spectrophotometry. Statistic discriminant analysis confirmed that the response patterns of the composite toward each chemical solvent could be distinguished among non polar and low polar solvents, but not high polar solvents.