Polyaniline composite coatings interrogated by a nulling optical-transmittance bridge for sensing low concentrations of ammonia gas

Citation
Me. Nicho et al., Polyaniline composite coatings interrogated by a nulling optical-transmittance bridge for sensing low concentrations of ammonia gas, SENS ACTU-B, 76(1-3), 2001, pp. 18-24
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
SENSORS AND ACTUATORS B-CHEMICAL
ISSN journal
0925-4005 → ACNP
Volume
76
Issue
1-3
Year of publication
2001
Pages
18 - 24
Database
ISI
SICI code
0925-4005(20010601)76:1-3<18:PCCIBA>2.0.ZU;2-H
Abstract
Polyaniline (PANI) is a pi -conjugated polymer that shows electric and opti cal property changes, when it is in contact with oxidant/reductor chemicals . In particular, the interaction between the conductive form of PANI, the e meraldine salt (ES), and the NH3 gas results in a decrease of the polaron d ensities inside the band gap of the organic material. In this work, the opt ical-transmittance changes detected in PANI coatings as a function of the s ensing ammonia gas concentrations are studied by using a nulling optical-tr ansmittance bridge with a 632 nm laser (He-Ne) source, which allows a sensi tive monitoring of optical property changes. It is observed that the conduc tive PANI-polymethyl methacrylate (PMMA) composite coatings are sensitive f or very low concentrations of HN3 (from similar to 10 to 4000 ppm, dependin g on the PANI films' electrical conductivity), and their optical response i s reversible as the reduction gas is removed by N-2. (C) 2001 Elsevier Scie nce B.V. All rights reserved.