Geometrically and chemically anisotropic particles at an oil–water interface

We present the behaviour of particles with chemical and geometrical anisotropy at a planar oil–water interface. We find that Janus cylinders with a small aspect ratio adopt an upright configuration, whereas the particles with a large aspect ratio exhibit both the upright and tilted configurations, which can be explained by the presence of two minima in the attachment energy profile. Such unique configurations significantly affect their assembly structure and lateral interactions. In particular, we observe strong capillary attractions between two tilted Janus cylinders and show that the scaling behaviour of the interaction depends on the lateral alignments of two cylinders. Consequently, this capillarity leads to a variety of assembled structures, which we attribute to the quasi-quadrupolar interface deformation observed around each particle.