Thermal properties of the γ-Fe₂O₃/poly(methyl methacrylate) core/shell nanoparticles

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• 作者：Ninjbadgar ; Tsedev ; Yamamoto ; Shinpei ; Takano ; Mikio
• 关键词：Core/shell nanoparticle ; Polymer degradation ; Structural transformation ; Maghemite
• 刊名：Solid State Sciences
• 出版年：2005
• 出版时间：January, 2005
• 年：2005
• 卷：7
• 期：1
• 页码：33-36
• 全文大小：322 K

文摘

Thermal properties of γ-Fe₂O₃/poly(methyl methacrylate) (PMMA) core/shell particles with an average core size of 4 nm were studied through measurements of thermogravimetry, powder X-ray diffraction and magnetization. The thermal degradation of the PMMA shell in the air was found to occur at temperatures lower by about 60 °C than that of free PMMA. Random scission of the PMMA chains seemed to be catalyzed by the core oxide. The γ-Fe₂O₃ to α-Fe₂O₃ structural transformation took place at different temperatures depending upon the shell material. Namely, α-Fe₂O₃ was the only product for the caprylate-capped γ-Fe₂O₃ nanoparticles treated at 400 °C, whereas γ-Fe₂O₃ still remained for the γ-Fe₂O₃/PMMA composite treated at 500 °C. It is possible that some species containing silicon of the polymerization initiator origin were formed on the surface and prevented interparticle atomic diffusions needed for the γ–α transformation.