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Investigation of the Conformational Changes of a Conducting Polymer in Gas Sensor Active Layers by Means of Polarization-Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS).

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journal contribution
posted on 26.02.2013, 00:00 by Luciano Caseli, Jonas Gruber, Rosamaria W. C. Li, Laura O. Péres
Polarization-Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) was employed to observe the changes in the molecular conformation of poly­(2-phenyl-1,4-xylylene) (PPPX) films that occurred after exposure to organic solvent vapors. The PPPX films were supported on solid matrixes by casting, spin-coating, and Langmuir–Blodgett (LB) techniques. The results show that the polymer is sensitive to the solvent vapors, which affect some of the vibration dipole moments, as detected by PM-IRRAS. The sensitivity depends on the method employed to immobilize the polymer, with more significant changes in films formed using techniques that result in a less systematically organized conformation. This feature enables the use of surface vibration spectroscopy to detect organic solvent vapors and may be applied in an artificial nose.