When a particle adsorbs at a liquid interface, the 3-phase contact line geometry depends on the shape of the particle and of the liquid interface. The shape of the contact line is the key to controlling capillary forces among particles, and is therefore a useful means to direct assembly of interfacial particles. We measured the shape of the contact line around millimeter-sized PDMS-coated glass spheres at water/air interfaces with anisotropic shapes. We studied the advancing and receding conditions separately. We focused on interfaces with a cylindrical shape, where the predominant deformation of the meniscus and the contact line both have quadrupolar cos(2ϕ) symmetry. We related the measured magnitude of the quadrupolar deformation to the applied vertical force on the sphere and the interface's deviatoric curvature, D₀. For modest curvature (D₀ < 0.1 × sphere radius), our results agree with the theoretical prediction for free particles. At higher curvature, the measurements exceed the theory. The theory appears to apply even when there is contact-angle hysteresis, as long as the measured contact angle is used rather than the equilibrium (Young-Dupré) angle. The magnitude of the quadrupolar deformation depends on the applied force. Together, these results show the range of validity of the theory.

中文翻译：

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各向异性流体界面处结合的球形颗粒周围接触线的变形

当颗粒在液体界面处吸附时，三相接触线的几何形状取决于颗粒和液体界面的形状。接触线的形状是控制颗粒间毛细作用力的关键，因此是指导界面颗粒组装的有用手段。我们在具有各向异性形状的水/空气界面处测量了毫米级PDMS涂层玻璃球周围的接触线形状。我们分别研究了前进和后退条件。我们针对接口具有圆筒形形状，其中弯月面的主要变形和接触线都具有四极COS（2 φ）对称。我们将四极变形的测量值与施加在球体上的垂直力和界面的偏曲率D ₀关联起来。对于适度的曲率（D ₀ <0.1×球半径），我们的结果与自由粒子的理论预测相符。在较高的曲率下，测量结果超出了理论范围。该理论似乎也适用，即使存在接触角滞后，只要使用测量的接触角而不是平衡（杨-杜普）角即可。四极变形的大小取决于所施加的力。这些结果加在一起表明了该理论的有效性范围。