Probing DLVO forces using interparticle magnetic forces: Transition from secondary-minimum to primary-minimum aggregation
Probing DLVO forces using interparticle magnetic forces: Transition from secondary-minimum to primary-minimum aggregation
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DOI：
10.1021/la0015260
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发表时间：
2001-10-02
期刊：
影响因子：
3.9
通讯作者：
Tsouris, C
中科院分区：
文献类型：
--
作者：
Chin, CJ;Yiacoumi, S;Tsouris, C
本文研究了超顺磁胶乳胶体粒子从次级最小聚集到初级最小聚集的转变。这种转变所需的磁感应强度是根据扩展的Derjaguin-Landau-Verwey-Overbeek （DLVO）理论计算的，该理论包括范德华力、静电力、磁偶极子力以及非DLVO疏水引力。用链偶极子模型估计磁偶极子势。从二级最小聚集到初级最小聚集发生转变时的磁感应强度是通过可视化链的形成和破裂实验确定的。实验值与理论值吻合较好，适用于本研究的小颗粒。研究发现，较大颗粒在狭窄毛细管中的过渡磁感应强度的实验值与理论预测值有明显偏差。然而，从宽毛细管中得到的过渡磁感应强度与理论值吻合得很好。这种行为表明，在狭窄的毛细管中，颗粒之间的排斥力大小减小。
The transition from secondary-minimum to primary-minimum aggregation of superparamagnetic colloidal latex particles is investigated in this study. The magnetic induction needed for this transition is calculated from the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which includes van der Waals, electrostatic, and magnetic-dipole forces as well as non-DLVO hydrophobic attraction. A chain-dipole model is used to estimate the magnetic-dipole potential. The magnetic induction at which the transition from secondary- to primary-minimum aggregation occurs is experimentally determined from visualization of chain formation and breakup. Experimental and theoretical values of transitional magnetic induction show good agreement for the small particles used in this study. The experimental value of the transitional magnetic induction of relatively large particles in a narrow capillary tube is found to deviate significantly from that predicted by theory. However, the transitional magnetic induction obtained from a wide capillary agrees well with the theoretical value. This behavior indicates that, in the narrow capillary, the magnitude of the repulsive force between the particles decreases.