Gelification: An Effective Measure for Achieving Differently Sized Biocompatible Fe3O4 Nanocrystals through a Single Preparation Recipe

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• 作者：Qiaojuan Jia ; Jianfeng Zeng ; Ruirui Qiao ; Lihong Jing ; Liang Peng ; Fenglong Gu ; Mingyuan Gao
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：December 7, 2011
• 年：2011
• 卷：133
• 期：48
• 页码：19512-19523
• 全文大小：1222K
• 年卷期：v.133,no.48(December 7, 2011)
• ISSN：1520-5126

文摘

Biocompatible Fe₃O₄ nanocrystals were synthesized through the pyrolysis of ferric acetylacetonate (Fe(acac)₃) in diphenyl oxide, in the presence of 伪,蠅-dicarboxyl-terminated polyethylene glycol (HOOC鈥揚EG鈥揅OOH) and oleylamine. Unusual gelification phenomena were observed from the aliquots extracted at different reaction stages after they were cooled to room temperature. By reaction time, the average size of the Fe₃O₄ nanocrystals was tuned from 5.8 to 11.7 nm with an equilibrium size around 11.3 nm. By increasing the gelification degree of the stock solution, the equilibrium size of the Fe₃O₄ nanocrystals was further increased from 11.3 to 18.9 nm. The underlying gel formation mechanism was investigated by using ultraviolet鈥搗isible absorption spectroscopy and Fourier transform infrared spectroscopy. The results suggest that the complexation between HOOC鈥揚EG鈥揅OOH and Fe(acac)₃, with the help of oleylamine, results in large molecular networks, which are responsible for the gelification of the stock solution, while the interaction between the fragment of the molecular network and Fe₃O₄ nanocrystal is responsible for the second gelification process observed during the early stage of reflux. To further investigate the particle growth behavior, small molecules released during the preparation were collected and analyzed by using photoelectron spectroscopy/photoionization mass spectroscopy (PES/PIMS). It was demonstrated that the pyrolysis of the Fe precursor is strongly correlated with the particle growth process. Further numerical simulations reveal that the first gelification process induced by the complexation between HOOC鈥揚EG鈥揅OOH and Fe(acac)₃ largely alters the pyrolysis behavior of the Fe precursor; consequently, the equilibrium size of the resultant Fe₃O₄ nanocrystals can effectively be tuned by the gelification degree of the stock solution.