Pathmamanoharan C, Philipse AP
Debye Institute, Utrecht University, Padualaan 8, Utrecht, 3584 CH, The Netherlands
J Colloid Interface Sci. 1998 Sep 15;205(2):340-353. doi: 10.1006/jcis.1998.5589.
A single-step method to synthesize monodisperse metallic cobalt particles of diameter around 8 nm is described. The particles are sterically stabilized by modified polyisobutene and form stable ferrofluids in toluene. The core-shell cobalt spheres have a narrow size distribution and are nonaggregated. Various techniques, such as infrared spectroscopy, X-ray diffraction, and elemental analysis establishes the presence of grafted modified polyisobutene on the surface of cobalt particles. The hydrodynamic thickness of the grafted polyisobutene calculated from sedimentation and viscosity measurements and independently from the dynamic light scattering is ca. 10 nm. The dependence of magnetization has been measured for ferrofluid, showing superparamagnetic behavior above 247 K. Due to anisotropy, superposition of magnetic curves is not observed below this temperature. The concentration dependence of the sedimentation coefficient agrees qualitatively with the theory for dipolar spheres. SAXS data on concentrated ferrofluid dispersion indicate interpenetration of polyisobutene chains grafted to the cobalt particles. Copyright 1998 Academic Press.
本文描述了一种合成直径约8nm的单分散金属钴颗粒的单步方法。这些颗粒通过改性聚异丁烯进行空间稳定化，并在甲苯中形成稳定的铁磁流体。核壳钴球具有窄的尺寸分布且不聚集。各种技术，如红外光谱、X射线衍射和元素分析，证实了钴颗粒表面存在接枝的改性聚异丁烯。通过沉降和粘度测量并独立于动态光散射计算得到的接枝聚异丁烯的流体动力学厚度约为10nm。已测量了铁磁流体的磁化强度依赖性，结果表明在247K以上呈现超顺磁性行为。由于各向异性，在此温度以下未观察到磁曲线的叠加。沉降系数的浓度依赖性与偶极球体理论定性相符。关于浓铁磁流体分散体的小角X射线散射数据表明接枝到钴颗粒上的聚异丁烯链相互渗透。版权所有1998年学术出版社。
