Dong Lichun, Johnson Duane T
Department of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, AL 35487-0203, USA.
Langmuir. 2005 Apr 26;21(9):3838-49. doi: 10.1021/la047851v.
In this paper, the adsorption energy of an acicular (prolate and cylindrical) particle onto a liquid-fluid interface and the effect of the line tension are investigated. The results show that, without line tension, acicular particles always prefer to lie flat in the plane of the interface. However, line tension plays a significant role in determining the adsorption of an acicular particle. First, the line tension creates an energy barrier for the adsorption of particles onto an interface. The planar configuration has a larger energy barrier due to the longer contact line. Therefore, the particles prefer to enter the interface in a homeotropic configuration and then rearrange to a planar configuration or an oblique configuration with a small tilt angle. Second, for prolate particles, an energy maximum occurs at some tilt angles when the line tension is large. Therefore, once the prolate particle is adsorbed on the interface in a homeotropic configuration or with a larger tilt angle, it must conquer an energy barrier to rearrange to a planar configuration. For cylindrical particles, when the line tension is higher, the planar configuration will not be the most energy-favorable configuration. The cylindrical particles prefer to stay in the interface with a small tilt angle.
本文研究了针状（长径比大且呈圆柱形）颗粒在液-液界面上的吸附能以及线张力的影响。结果表明，在没有线张力的情况下，针状颗粒总是倾向于平躺于界面平面内。然而，线张力在决定针状颗粒的吸附方面起着重要作用。首先，线张力为颗粒吸附到界面上创造了一个能量势垒。由于接触线较长，平面构型具有更大的能量势垒。因此，颗粒倾向于以垂直排列构型进入界面，然后重新排列成平面构型或小倾斜角的倾斜构型。其次，对于长径比大的颗粒，当线张力较大时，在某些倾斜角处会出现能量最大值。因此，一旦长径比大的颗粒以垂直排列构型或较大倾斜角吸附在界面上，它必须克服一个能量势垒才能重新排列成平面构型。对于圆柱形颗粒，当线张力较高时，平面构型将不是能量最有利的构型。圆柱形颗粒倾向于以小倾斜角留在界面中。
