Polypyrrole one-dimensional nanostructures (nanotubes, nanobelts and nanofibers) were prepared using three various dyes (Methyl Orange, Methylene Blue and Eriochrome Black T). Their high electrical conductivity (from 17.1 to 60.9 S cm-1), good thermal stability (in the range from 25 to 150 °C) and resistivity against ageing (half-time of electrical conductivity around 80 days and better) were used in preparation of lightweight and flexible composites with silicone for electromagnetic interference shielding in the C-band region (5.85-8.2 GHz). The nanostructures' morphology and chemical structure were characterized by scanning electron microscopy, Brunauer-Emmett-Teller specific surface measurement and attenuated total reflection Fourier-transform infrared spectroscopy. DC electrical conductivity was measured using the Van der Pauw method. Complex permittivity and AC electrical conductivity of respective silicone composites were calculated from the measured scattering parameters. The relationships between structure, electrical properties and shielding efficiency were studied. It was found that 2 mm-thick silicone composites of polypyrrole nanotubes and nanobelts shield almost 80% of incident radiation in the C-band at very low loading of conductive filler in the silicone (5% w/w). Resulting lightweight and flexible polypyrrole composites exhibit promising properties for shielding of electromagnetic interference in sensitive biological and electronic systems.
- MeSH
- Azo Compounds chemistry MeSH
- Electromagnetic Radiation * MeSH
- Methylene Blue chemistry MeSH
- Microscopy, Electron, Scanning MeSH
- Nanostructures chemistry radiation effects ultrastructure MeSH
- Nanotubes chemistry radiation effects ultrastructure MeSH
- Nanofibers chemistry radiation effects MeSH
- Polymers chemistry radiation effects MeSH
- Pyrroles chemistry radiation effects MeSH
- Silicones chemistry radiation effects MeSH
- Publication type
- Journal Article MeSH
The polyaniline (PANI) base was ball-milled with silver nitrate in the solid state. Samples were prepared at various mole ratios of silver nitrate to PANI constitutional units ranging from 0 to 1.5 for three processing times, 0, 5, and 10 min. The emeraldine form of PANI was oxidized to pernigraniline, and the silver nitrate was reduced to metallic silver. Nitric acid is a byproduct, which may protonate the residual emeraldine and pernigraniline. The changes occurring in the structure of PANI are discussed on the basis of Fourier transform IR and Raman spectroscopies. Raman spectra revealed the formation of pernigraniline salt. The reaction between the two nonconducting components, emeraldine base and silver nitrate, produced a mixture of two conducting components, emeraldine or pernigraniline nitrate and metallic silver. The accompanying conductivity changes were determined. The increase in the conductivity of the original base, 10(-9) S cm(-1), up to 10(-2) S cm(-1) was found to depend on the mole ratio of silver nitrate to PANI base and on the processing time of the components in the ball mill.
- MeSH
- Aniline Compounds chemistry MeSH
- Time Factors MeSH
- Models, Chemical MeSH
- Silver Nitrate chemistry MeSH
- Electric Conductivity MeSH
- Oxygen chemistry MeSH
- Chemistry, Organic methods MeSH
- Polymers chemistry MeSH
- Spectrum Analysis, Raman methods MeSH
- Spectroscopy, Fourier Transform Infrared methods MeSH
- Silver chemistry MeSH
- Materials Testing MeSH
- Microscopy, Electron, Transmission methods MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Tato práce představuje úvodní fyzikálně chemickou studii, která se zabývá přípravou atelokolagenových destiček sycených lokálními anestetiky, modelováním uvolňování anestetika z kolagenovématrice in vitro a ověřením analytických postupů (dc-polarografie, UV-VIS spektrofotometrie) prostanovení cinchokainu. Tato studie je doplněna experimenty in vivo, které potvrzují použitelnosttohoto nového materiálu pro depotizaci anestetik.
The paper presents an introductory physicochemical study dealing with the preparation of atelocol-lagen felt saturated with local anesthetics, with the modelling of the release of the anesthetic fromthe collagen matrix in vitro, and with the checking of the corresponding analytical procedures(dc-polarography and UV-VIS spectrophotometry) for the determination of cinchocaine. The studyis supplemented with experiments in vivo that confirm the usability of the new material for thedepot formation of local anesthetics.
