Department of Chemical Engineering, Kyung Hee University , Yongin 17104, South Korea.
Department of Polymer Engineering, The University of Suwon , Hwaseong, Gyeonggi 18323, South Korea.
Langmuir. 2018 Jan 9;34(1):384-394. doi: 10.1021/acs.langmuir.7b03882. Epub 2017 Dec 27.
Heterogeneous capillary interactions between ellipsoid particles at the oil-water interface were measured via optical laser tweezers. Two trapped particles were aligned in either tip-to-tip (tt) or side-to-side (ss) configurations via the double-trap method and were released from the optical traps, leading to particle-particle attractions due to the capillary forces caused by quadrupolar interface deformation. On the basis of image analysis and calculations of the Stokes drag force, the capillary interactions between two ellipsoid particles with the same aspect ratio (E) were found to vary with the particle pairs that were measured, indicating that the interactions were nondeterministic or heterogeneous. Heterogeneous capillary interactions could be attributed to undulation of the interface meniscus due to chemical and/or geometric particle heterogeneity. The power law exponent for the capillary interaction U ≈ r was found to be β ≈ 4 and was independent of the aspect ratio and particle configuration in long-range separations. Additionally, with regard to the tt configuration, the magnitude of the capillary force proportionally increased with the E value (E > 1) when two ellipsoid particles approached each other in the tt configuration.
通过光学激光镊子测量了油水界面上椭球粒子之间的各向异性毛细相互作用。通过双阱方法将两个捕获的粒子对准尖端对尖端（tt）或侧面到侧面（ss）配置，并从光阱中释放出来，由于四极界面变形引起的毛细力导致粒子间相互吸引。基于图像分析和斯托克斯阻力的计算，发现两个具有相同纵横比（E）的椭球粒子之间的毛细相互作用随测量的粒子对而变化，表明相互作用是不确定的或各向异性的。各向异性毛细相互作用可能归因于界面弯月面的波动，这是由于化学和/或几何粒子不均匀性引起的。在长程分离中，毛细相互作用 U ≈ r 的幂律指数被发现为β ≈ 4，并且与纵横比和粒子构型无关。此外，对于 tt 构型，当两个椭球粒子在 tt 构型中彼此接近时，毛细力的大小与 E 值成比例增加（E > 1）。
