Properties of Vapor Detector Arrays Formed through Plasticization of Carbon Black−Organic Polymer Composites

Abstract

Arrays of vapor detectors have been formed through addition of varying mass fractions of the plasticizer diethylene glycol dibenzoate to carbon black-polymer composites of poly(vinyl acetate) (PVAc) or of poly(N-vinylpyrrolidone). Addition of plasticizer in 5% mass fraction increments produced 20 compositionally different detectors from each polymer composite. Differences in vapor sorption and permeability that effected changes in the dc electrical resistance response of these compositionally different detectors allowed identification and classification of various test analytes using standard chemometric methods. Glass transition temperatures, Tg, were measured using differential scanning calorimetry for plasticized polymers having a mass fraction of 0, 0.10, 0.20, 0.30, 0.40, or 0.50 of plasticizer in the composite. The plasticized PVAc composites with Tg < 25 degrees C showed rapid responses at room temperature to all of the test analyte vapors studied in this work, whereas composites with Tg > 25 degrees C showed response times that were highly dependent on the polymer/analyte combination. These composites showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the Tg of the composite and for determining the temperature or plasticizer mass fraction above which rapid resistance responses could be obtained for all members of the test set of analyte vapors. The plasticization approach provides a method for achieving rapid detector response times as well as for producing a large number of chemically different vapor detectors from a limited number of initial chemical feedstocks.

Sensors and Systems for the Detection of Explosive Devices - An Overview

“…better selectivity, multicomponent analysis, and analyte recognition. Some electronic noses use fluorescent polymers, fiber-optic cables [29], arrays of different polymeric thin film sensors [30], gold nanoclusters deposited on interdigital microelectrode arrays [31], surface acoustic wave [32,33], quartz crystal microbalance gas sensors, and micro-electromechanical systems [34]. In future these systems will replace some of the larger and more expensive detection devices.…”

Towards optoelectronic detection of explosives

“…The devices perform multi− component analysis and analyte recognition. In the sensors, fluorescent polymers [30], arrays of different polymeric thin film [31], gold nanoclusters deposited on microelectrode arrays [32], surface acoustic wave [33,34], quartz crystal microbalance devices, and micro−electromechanical sys− tems (MEMS) [35] are used. Their detection limit reaches the value of about 1 ppm [36].…”

Development of chemiresponsive sensors for detection of common homemade explosives.

“…This swelling causes disruption in the conduction pathways within the elastomer resulting in an increase in the resistivity of the material. In order to differentiate analytes, arrays of chemiresistors made with different elastomers are used and pattern recognition is used to match the sensor responses with known analyte responses [1][2][3][4][5][6][7][8][9][10][11][12]. In addition to the equilibrium sensor response, work has also been performed investigating the kinetic response of chemiresistors when exposed to high vapor pressure materials [13][14][15].…”