The capillary interaction force between spherical Janus particles trapped at the air–water interface is measured using a time-sharing optical tweezer (bond number ≪ 1). One face of the particles is hydrophilic, and the other one, hydrophobic. Measured force goes from almost pure quadrupolar to almost pure hexapolar interaction due to the three-phase contact line corrugation. Measured force curves are modeled as a sum of power laws, Ar^−α + Br^−β + Cr^−γ, obtained from an expansion in capillary multipoles. The mean values for the exponents of particle pairs of 3 μm are 〈α〉 = 5.05 ± 0.12, 〈β〉 = 7.02 ± 0.03, and 〈γ〉 = 5.96 ± 0.03. For particles pairs of 5 μm, we find 〈α〉 = 5.02 ± 0.04, 〈β〉 = 6.94 ± 0.06, and 〈γ〉 = 5.80 ± 0.05. In both cases, A < 0, B < 0, and C > 0.

中文翻译：

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测量在平坦的空气/水界面处捕获的Janus胶体颗粒之间的毛细管相互作用力。

使用分时光学镊子（键数≪ 1）测量捕获在空气-水界面处的球形Janus颗粒之间的毛细管相互作用力。颗粒的一面是亲水的，另一面是疏水的。由于三相接触线的起皱，测得的力从几乎纯的四极相互作用变为几乎纯的六极相互作用。将测得的力曲线建模为幂定律的总和，即Ar ^{- α} + Br ^{- β} + Cr ^{- γ}，它是通过毛细管多极杆的膨胀获得的。3μm粒子对的指数平均值为< α > = 5.05±0.12，< β > = 7.02±0.03和< γ〉 ＝ 5.96±0.03。对于5μm的粒子对，我们发现< α > = 5.02±0.04，< β > = 6.94±0.06和< γ > = 5.80±0.05。在这两种情况下，A <0，B <0和C > 0。