کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1443777 | 1509459 | 2008 | 7 صفحه PDF | دانلود رایگان |
Polypyrrole (PPy) powders were synthesized chemically using the oxidant ammonium persulfate (APS). The free radical scavenging properties were evaluated using a form of the α,α-diphenyl-β-picrylhydrazyl (DPPH) assay adapted for use with 1.0 mg amounts of conducting polymer powders. A lower scavenging capacity was obtained when a higher ratio of APS to pyrrole was used in the chemical synthesis which also led to a decrease in polymer conductivity and doping level as determined by the amount of (bi)sulfate present given by elemental analyses. The occurrence of overoxidation of polypyrrole at a higher oxidant level was confirmed in FTIR spectra by the presence of a carbonyl group. PPy prepared at a lower APS/pyrrole ratio contained more bipolaron charge carriers, which were converted to polarons upon initial reduction with hydrazine. More complete reduction with hydrazine led to a loss of (bi)sulfate dopant, but to improved DPPH radical scavenging, confirming that the conducting polymer is acting as a reducing agent in scavenging DPPH radicals.
Journal: Synthetic Metals - Volume 158, Issues 21–24, December 2008, Pages 946–952