Spectroscopic study of the photodegradation pathways of silver-backed polyacrylonitrile films

Abstract

Ultraviolet radiation in the regions 266 < X < 400 nm and 250 < X < 400 nm has been employed to study the oxidative photodegradation pathways for silver-backed polyacrylonitrile film. Measurements based on Fourier transform infrared reflection absorbance (FTIR-RA) spectroscopy were supported by electron paramagnetic resonance (EPR) studies. Isotopic 13CN PAN was used to confirm some photodegradation products. Upon irradiation at wavelengths below 266 nm the polymer turns yellowish-brown and also increases in electrical conductivity, suggesting the presence of a chromophore system of the type (>C=N-)".

SERS studies of polymers on metal surfaces. 4. Cyclization and graphitization of polyacrylonitrile on rough silver surfaces

“…4 Another report revealed that the polymer may undergo facile photodegradation on a smooth silver surface upon ultraviolet irradiation at wavelengths in the region 250 < < 400 nm. Below 266 nm, the silver-backed PAN turned yellowish brown and increased in electrical conductivity, suggesting the presence of a chromophore system of the type-(0=N)"n. 5 We report here our surfaceenhanced Raman scattering (SERS) studies of structural changes of PAN on chemically roughened silver surfaces. Since the electrical conductivity of the double-coupled conjugated system can be increased by about 10 orders of magnitude upon doping,6 knowledge of such structural changes on metal surfaces should help not only in the preparation of electrically conductive polymeric modifiers on metal electrodes but also in the understanding of the mechanisms of the conduction.…”

Surface Reactions on Polymer Thin Films Studied by Surface-Enhanced Raman Scattering

“…Another report revealed that the polymer may undergo facile photodegradation on a smooth silver surface upon ultraviolet irradiation at wavelengths in the region from 250−400 nm. Below 266 nm, the silver-backed PAN turned yellowish brown and increased in electrical conductivity, suggesting the presence of a chromophore system of the type −(CN)− n . We report here our surface-enhanced Raman scattering (SERS) studies of the structural changes of PAN beneath the chemically deposited silver layer.…”

Characterization of mono- and multi-molecular assemblies at glassy carbon and noble metals by ex situ and in situ infrared external reflection spectroscopy

“…Other examples from the literature concerning the IR external reflection spectroscopy of polymer films can be found in the references. Various problems have been explored including the effects of ultra-violet radiation, heat, and weathering on the molecular structure of polymer films (45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58), the biocompatibility of polymer materials for use as prosthetic devices (59)(60), and the characterization of inorganic films at surfaces (61)(62)(63). This list represents an overview only and is not intended to be fiilly inclusive.…”