Use of conducting polypyrrole blends as gas sensors
TL;DR: In this paper, the use of polymeric blends formed by the controlled growth of doped polypyrrole chains in the interior of films of different dielectric polymers as sensors of the presence of representative examples of volatile organic compounds was discussed.
Abstract: We discuss the use of polymeric blends formed by the controlled growth of doped polypyrrole chains in the interior of films of different dielectric polymers as sensors of the presence of representative examples of volatile organic compounds. The dielectric films (of either (poly(caprolactone), poly(ethylene oxide), poly(methyl-methacrylate), poly(vinyl alcohol), or poly(vinyl-acetate)) containing an appropriate oxidizing agent were prepared atop a conducting glass substrate and the polymerization of polypyrrole was induced through the vapor phase technique, after exposure of the desired matrix to pyrrole vapor. The UV–vis–NIR spectra of the films were used to monitor the increase of their conductive character through the assessment of the intensity of the polaron band characteristic of the doped form of polypyrrole. The change of conductivity upon exposure to the volatile compounds used (methanol, ethanol, carbon tetrachloride and benzene) was adopted as a measure of the corresponding sensitiveness of the films. Differently to the previous case in which doped films of polypyrrole were examined as sensors (when a similar low level of response was found towards apolar compounds), now we have found that some of the blends (PMMA/PPY and PVA/PPY, in special) exhibit a particular sensitiveness to the polarity of the molecule of the vapor tested. We therefore suggest that the simultaneous use of such polypyrrole blends in an arrangement pattern can improve the efficiency of electronic nose devices.
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TL;DR: The experimental results show that these ammonia gas sensors are efficient since they are sensitive to ammonia, reversible and reproducible at room temperature.
143 citations
TL;DR: Inkjet-printed films of the conductive polymer polypyrrole have been used for vapour sensing at room temperature as mentioned in this paper, and a significant increase in conductivity was observed on the exposure of the films to the vapours of simple alcohols.
Abstract: Inkjet-printed films of the conductive polymer polypyrrole have been used for vapour sensing at room temperature. The electrical properties, sensitivity, reproducibility and stability of the polymer chemiresistors are reported. A significant increase in conductivity was observed on the exposure of the films to the vapours of simple alcohols. The value of the fractional resistance change, Δ R / R , of the films increased linearly with increasing concentrations of both ethanol and methanol. A relatively high Δ R / R value, approximately 90%, was obtained on exposure to 5000 parts per million of methanol. The response time of the inkjet-printed sensors to polar vapours was generally shorter than that for non-polar compounds. It is suggested that the increase in conductivity may be related to a vapour-induced change in the transfer of charge carriers between the polymer chains.
127 citations
TL;DR: In this paper, a second-order polynomial fit was applied to the polypyrrole (PPy) to investigate the tunable nature of the dedoping process and the calculated theoretical data showed strong correlation with the recent experimental reports.
Abstract: Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations at the UB3LYP/6-31G(d) level have been performed to investigate the tunable nature, i.e., doping and dedoping processes, of polypyrrole (PPy). The calculated theoretical data show strong correlation with the recent experimental reports, which validates our computational protocol. The calculated properties are extrapolated to the polymer (PPy) through a second-order polynomial fit. Changes in band gap, conductivity, and resistance of nPy and nPy-X (where n = 1–9 and X = +, NH3, and Cl) were studied and correlated with the calculated vibrational spectra (IR) and electronic properties. Upon doping, bridging bond distance and internal bond angles decrease (decrease in resistance over polymer backbone), whereas dedoping results in increases in these geometric parameters. In the vibrational spectrum, doping is characterized by an increase in the band peaks in the fingerprint region and/or red shifting of the spectral bands. Dedoping (9...
118 citations
TL;DR: A nano-composite core-shell Ag@SnO 2 material was synthesized by chemical reduction and characterized by temperature-programmed reduction (TPR), UV-visible reflective spectroscopy, high-resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray Spectroscopy (EDS) as discussed by the authors.
Abstract: A nano-composite core–shell Ag@SnO 2 material was synthesized by chemical reduction and characterized by temperature-programmed reduction (TPR), UV–visible reflective spectroscopy, high-resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray spectroscopy (EDS). SnO 2 , Ag/SnO 2 and Ag@SnO 2 were used to sense ethanol (C 2 H 5 OH) in an ethanol gas detection system. The SnO 2 material under 200 ppm ethanol gas exhibited a sensor response ( S = R air / R ethanol = (resistance of sensor signal of air)/(resistance of sensor signal of ethanol gas)), response time ( t 90 ) and recovery time ( t R90 ) were 1.54, 54 s and 85 s, respectively. Ag@SnO 2 materials had an improved sensor response of 2.24, with a shortened response time ( t 90 ) and recovery time ( t R90 ) of 34 s and 68 s, respectively. The bond strength between ethanol gas and the Ag@SnO 2 on which was adsorbed, determined by van der Waal's forces, and was calculated for a case in which more than 20 molecules were adsorbed. The mechanism of the sensing of ethanol gas, based on its adsorption, its reaction on the surface and its desorption is presented.
97 citations
TL;DR: A series of polypyrrole (PPy)/titanium dioxide (TiO2) nanocomposites were prepared in different polymerization conditions by "in situ" chemical oxidative polymerization as mentioned in this paper.
Abstract: A series of polypyrrole (PPy)/titanium dioxide (TiO2) nanocomposites were prepared in different polymerization conditions by ‘in situ’ chemical oxidative polymerization. The nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy spectra (XPS), and UV–Vis diffuse reflectance spectra. The photocatalytic degradation of methyl orange (MO) was chosen as a model reaction to evaluate the photocatalytic activities of TiO2/PPy catalysts. The results show that a strong interaction exists at the interface between TiO2 and PPy, the deposition of PPy on TiO2 nanoparticles can alleviate their agglomeration, PPy/TiO2 nanocomposites show stronger absorbance than neat TiO2 under the whole range of visible light. The obtained PPy/TiO2 nanocomposites exhibit significantly higher photocatalytic activity than the neat TiO2 on the degradation of MO aqueous solution under visible and UV light illumination. The reasons for improving the photocatalytic activity were also discussed.
90 citations
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Book•
01 Jan 1997
TL;DR: In this article, the properties of conjugated polymers and their properties were investigated at submicron scale with a scanning force microscope magnetic properties of conducting polymers Optically Detected Magnetic Resonance (ODMR).
Abstract: Vol 1: From electron acceptor molecules to photoinduced intramolecular electron transfer systems perylene based conductors tetrachalcogenafulvalenes, metal 1,2-dichalcogenolenes and their conductive salts conductive hetero-TCNQs molecular metals and superconductors based on transition metal complexes conductivity and superconductivity in doped fullerenes electrochemistry of fullerenes photophysics, charge separation and associated device applications of conjugated polymer/fullerene composites photoconductivity in fullerenes organic photoconductive materials for xenographic photoreceptors photoconductive polymers graphite intercalation compounds electrically conductive metallophthalocyanines electrically conductive Langmuir-Blogett films magnetism of stable organic radical crystals. Vol 2: Polyacetylene electrically conductive polyacetylene copolymers perconjugated organic polymer - early synthesis attempts and applications electrochemical synthesis of polyheterocycles and their applications (-conductive polymers prepared by organometallic polycondensation poly(p-phenylenes) - preparation techniques and general properties synthesis and properties of processable polythiophenes molecular conductive materials - from polythiophenes to oligothiophenes charge-state incorporation in bis-thienyl polyenes and thienylene polyenylene oligomers and polymers polypyrroles - from basic research to technological applications polythiophene and polypyrrole copolymers polyanilines electrically conductive polytoluidines silicon containing thiophene monomers, oligomers and polymers - synthesis, characterization and properties silicon and germanium containing conductive polymers polyazines - synthesis, structure, spectroscopy and conducting properties conductive metallophthalocyanine polymers conductive polymer blends and composites organometallic conductive polymers self-doped conductive polymers. Vol 3: Crystallography of conductive polymers the structure of polythiophenes photoelectron spectroscopy of conductive polymers spectroelectrochemistry and spectroscopy of conducting polymers structural investigation of soluble conjugated polymers and modification of their structure at submicron scale with a scanning force microscope magnetic properties of conducting polymers Optically Detected Magnetic Resonance (ODMR) Studies of conjugated polymer films, LEDs, and fullerenes microwave properties of conductives polymers electrochemistry of conjugated polymers electrocatalytic properties of conductive polymers due to dispersion physical and spectroscopic properties of polypyrrole films containing transition metal complexes as counteranions thin film properties of oligothiophenes electrochroism in polyanilines thermochromism and solvatochromism in polythiophenes degradation and stability of conductive polymers. Vol 4: Transport in conducting polymers electronic structure of (conjugated polymers). (Part contents)
2,272 citations
Book•
15 Feb 1988TL;DR: This chapter discusses Chemometrics and the Analytical Process, a large-scale comparison of two procedures for optimization of Analytical Chemical Methods, and its applications in Operations Research and Decision Making.
Abstract: 1. Chemometrics and the Analytical Process. 2. Precision and Accuracy. 3. Evaluation of Precision and Accuracy. Comparison of Two Procedures. 4. Evaluation of Sources of Variation in Data. Analysis of Variance. 5. Calibration. 6. Reliability and Drift. 7. Sensitivity and Limit of Detection. 8. Selectivity and Specificity. 9. Information. 10. Costs. 11. The Time Constant. 12. Signals and Data. 13. Regression Methods. 14. Correlation Methods. 15. Signal Processing. 16. Response Surfaces and Models. 17. Exploration of Response Surfaces. 18. Optimization of Analytical Chemical Methods. 19. Optimization of Chromatographic Methods. 20. The Multivariate Approach. 21. Principal Components and Factor Analysis. 22. Clustering Techniques. 23. Supervised Pattern Recognition. 24. Decisions in the Analytical Laboratory. 25. Operations Research. 26. Decision Making. 27. Process Control. Appendix. Subject Index.
1,423 citations
TL;DR: The human nose is still the primary instrument used to assess the smell or flavour of various industrial products today, despite considerable and sustained attempts to develop new electronic instrumentation capable of mimicking its remarkable ability as discussed by the authors.
Abstract: The human nose is still the primaryinstrument' used to assess the smell or flavour of various industrial products today, despite considerable and sustained attempts to develop new electronic instrumentation capable of mimicking its remarkable ability In this paper we review the research effort that has been carried out over the past 25 years or so to create an electronic nose Indoing so, we first provide a definition for the term electronic nose, and then discuss some of the technologies that have been explored in what is essentially an intelligent chemical array sensor systemwe summarize the applications of electronic noses to date and suggest where future applications may lie
1,079 citations
TL;DR: The tremendous advances made during the past decade in the chemistry, electrochemistry, physics, theory and processing of polyaniline and polypyrrole and their derivatives provide a broad solid foundation for future studies and technological applications as discussed by the authors.
608 citations
IBM1
TL;DR: The chronoabsorptometric results show that polypyrrole film grows linearly with time t and not t 1/2 as mentioned in this paper, which is consistent with the slow step in the growth process being a radical coupling step and not the diffusion of pyrrole to the electrode surface.
578 citations