Synthesis of Superparamagnetic Polymer−Ferrite Composites Using Surfactant Microstructures
| Autor: | Charles J. O'Connor, Joseph A. Akkara and, David L. Kaplan, Michael F. Herman, Murthy Tata, Nagesh S. Kommareddi, Vijay T. John, and Gary L. McPherson, Young-Sook Lee and |
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| Rok vydání: | 1996 |
| Předmět: |
Materials science
Spin glass General Chemical Engineering General Chemistry Coercivity Magnetic hysteresis Magnetic susceptibility Condensed Matter::Soft Condensed Matter Condensed Matter::Materials Science Remanence Condensed Matter::Superconductivity Materials Chemistry Ferrite (magnet) Microemulsion Composite material Superparamagnetism |
| Zdroj: | Chemistry of Materials. 8:801-809 |
| ISSN: | 1520-5002 0897-4756 |
| DOI: | 10.1021/cm940485o |
| Popis: | Superparamagnetic microspheres are prepared by incorporating nanometer-sized iron oxide crystals into micron-sized phenolic polymer particles. The synthesis of ferrite particles is conducted in the structured environment of water-in-oil microemulsions (reversed micelles). This is followed by the enzymatic polymerization of p-ethylphenol. The polymer precipitates in spherical morphologies and during precipitation incorporates ferrite nanocrystals into the polymeric matrix. SQUID (superconducting quantum interference device) generated magnetic hysteresis loops exhibit zero remanence and coercivity for the ferrite−polymer composite at room temperature, indicating the superparamagnetic nature of the composite. At very low temperatures, hysteretic effects, nonzero remanence, and coercivity are seen. Spin glass behavior is apparent at low temperatures from dc magnetic susceptibility measurements. Thermal and isothermal remanent magnetization measurements confirm the existence of the spin glass state. The compos... |
| Databáze: | OpenAIRE |
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