Optical evidence of electrochemical modification of polyaniline induced by tetra-fluoro-hydroquinone
| Autor: | E.S. Matveeva, M.J Gonzalez Tejera, R.C Patil |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
chemistry.chemical_classification
Conductive polymer Hydroquinone Mechanical Engineering Metals and Alloys Chemical modification Polymer Electrolyte Condensed Matter Physics Photochemistry Electronic Optical and Magnetic Materials chemistry.chemical_compound chemistry Mechanics of Materials Absorption band Polyaniline Polymer chemistry Materials Chemistry Polarization (electrochemistry) |
| Zdroj: | Synthetic Metals. 123:343-348 |
| ISSN: | 0379-6779 |
| Popis: | We have made an attempt to study electrochemically induced modification of ITO/PANI electrode in tetra-fluoro-hydroquinone (4F-hydroquinone) solution. The conditions at which the host molecule (of 4F-hydroquinone) incorporates into polyaniline were investigated, and the modifications in PANI electrode were monitored by optical absorption spectra measurements. PANI films were exposed to three different modifying conditions: a long-cycle polarization in acid solutions (pH range 0.4–3.2, potential limits between −0.35 and 0.8 V versus SCE) without and with 4F-hydroquinone added and a chemical interaction between PANI and 4F-quinone solution for different times at pH 6. We found that modification is a pH-dependent process and can only occur at pH above 3. Cyclic treatment in electrolyte containing 4F-hydroquinone at pH 3.2 leads to 4F-hydroquinone residue incorporation into the polymer backbone that can be viewed as a new optical absorption band of the polymer (550–600 nm). Other optical transitions of PANI are also changed due to modification. A π–π ∗ transition (320–350 nm) is broader and seems to contain two components. A localized polaron absorption (435–450 nm) is several folds more intensive in modified PANI. A conduction band absorption (800–820 nm) shows a blue shift and this band still appears at potentials where the loss of conductivity has occurred for non-modified polymer. We have proposed that modification emerged from interaction of the acid polymer centers and 4F-hydroquinone molecules oxidized during cycling. |
| Databáze: | OpenAIRE |
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