Self-assembly of Janus (or “patchy”) particles is dependent on the precise interaction between neighboring particles. Here, the orientations of two amphiphilic Janus spheres within a dimer in an explicit fluid are studied with high geometric resolution. Molecular dynamics simulations and semianalytical energy calculations are used with hard- and soft-sphere Lennard-Jones potentials, and temperature and hydrophobicity are varied. The most probable center-center-pole angles are in the range of ${40}^{\circ }–{55}^{\circ }$ with pole-to-pole alignment not observed due to orientational entropy. Angles near ${90}^{\circ }$ are energetically unfavored due to solvent exclusion, and the relative azimuthal angle between the spheres is affected by solvent ordering. Relatively large polar angles become more favored as the hydrophobic surface area (i.e., Janus balance) is increased.

• Received 4 March 2021
• Revised 16 June 2021
• Accepted 22 July 2021

DOI:https://doi.org/10.1103/PhysRevE.104.024602