Anisotropic entropy-driven potential

This study investigates the Entropy-Driven Potential (EDP) between two infinitely long, parallel semi-cylindrical particles immersed in a hard-sphere solvent. The research focuses on how the mutual orientations of the particles and the bulk solvent density influence the EDP curves. Using the classical density functional theory, we calculated the potential of mean force to understand the entropic interactions. Since the system considered in this study excludes energetic interactions, the derived potential of mean force directly corresponds to the EDP. The key results reveal that in the EDP curve, the depth and height of attractive wells and repulsive barriers, their positions, as well as patterns in the EDP behavior, vary significantly with orientation and solvent density. Notably, some configurations exhibit purely repulsive interactions due to specific particle alignments. The study identifies three dominant mechanisms driving the EDP: (1) overlap of exclusion zones, which increases entropy and results in attraction, (2) adsorption–desorption of solvent particles on particle surfaces, which decreases entropy and contributes to repulsion and (3) collision-induced forces that generate attractive potentials as particles approach each other. These findings provide new insights into anisotropic entropic interactions, which are critical for designing advanced materials and technologies in fields like nanotechnology, biomedicine and colloidal science. The research highlights the novelty of studying the anisotropic nature of the excluded volume and their potential to inform the development of materials with tunable properties.