Universidade Federal do Rio de Janeiro/ Instituto de Macromoléculas, Centro de Tecnologia, Rio de Janeiro, RJ, Brazil.
Mater Sci Eng C Mater Biol Appl. 2013 Oct;33(7):3994-4001. doi: 10.1016/j.msec.2013.05.035. Epub 2013 May 25.
Flexible magnetic membranes with high proportion of magnetite were successfully prepared by previous impregnation of the never dried bacterial cellulose pellicles with ferric chloride followed by reduction with sodium bisulfite and alkaline treatment for magnetite precipitation. Membranes were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating magnetometer, field emission scanning electron microscopy (FEG-SEM) and impedance spectroscopy. Microwave properties of these membranes were investigated in the X-band (8.2 to 12.4 GHz). FEG-SEM micrographs show an effective coverage of the BC nanofibers by Fe3O4 nanoparticles. Membranes with up to 75% in weight of particles have been prepared after 60 min of reaction. Magnetite nanoparticles in the form of aggregates well adhered to the BC fibers were observed by SEM. The average crystal sizes of the magnetic particles were in the range of 10±1 to 13±1 nm (estimated by XRD). The magnetic particles in the BC pellicles presented superparamagnetic behavior with a saturation magnetization in the range of 60 emu g(-1) and coercive force around 15 Oe. These magnetic pellicles also displayed high electrical permittivity and a potential application as microwave absorber materials.
先前曾用氯化铁对从未干燥的细菌纤维素膜进行浸渍，随后用亚硫酸氢钠还原并用碱性处理进行磁铁矿沉淀，成功制备了具有高比例磁铁矿的柔性磁性膜。通过拉曼光谱、傅里叶变换红外光谱（FTIR）、X 射线衍射（XRD）、振动磁强计、场发射扫描电子显微镜（FEG-SEM）和阻抗谱对膜进行了表征。这些膜的微波特性在 X 波段（8.2 至 12.4GHz）进行了研究。FEG-SEM 显微照片显示，BC 纳米纤维被 Fe3O4 纳米颗粒有效覆盖。在反应 60 分钟后，已经制备出了重量高达 75%的颗粒的膜。SEM 观察到以团聚体形式存在的磁铁矿纳米颗粒很好地附着在 BC 纤维上。磁性颗粒的平均晶体尺寸在 10±1 至 13±1nm 范围内（通过 XRD 估计）。BC 膜中的磁性颗粒表现出超顺磁性，饱和磁化强度在 60 emu g-1 范围内，矫顽力约为 15 Oe。这些磁性膜还显示出高介电常数，有作为微波吸收材料的潜在应用。
