title: Casimir-like forces at the percolation transition.
abstract: Percolation and critical phenomena show common features such as scaling and universality. Colloidal particles, immersed in a solvent close to criticality, experience long-range effective forces named critical Casimir forces. Building on the analogy between critical phenomena and percolation, here we explore the possibility of observing long-range forces near a percolation threshold. To this aim, we numerically evaluate the effective potential between two colloidal particles dispersed in a chemical sol, and we show that it becomes attractive and long-ranged on approaching the sol percolation transition. We develop a theoretical description based on a polydisperse Asakura-Oosawa model that captures the divergence of the interaction range, allowing us to interpret such effect in terms of depletion interactions in a structured solvent. Our results provide the geometric analogue of the critical Casimir force, suggesting a novel way for tuning colloidal interactions by controlling the clustering properties of the solvent.
authors: 1] CNR-ISC, UOS Sapienza, P.le A. Moro 2, Roma I-00185, Italy [2] Dipartimento di Fisica, 'Sapienza' Università di Roma, P.le A. Moro 2, Roma I-00185, Italy.
authors: Nicoletta
authors: N
authors: Gnan
authors: 1] CNR-ISC, UOS Sapienza, P.le A. Moro 2, Roma I-00185, Italy [2] Dipartimento di Fisica, 'Sapienza' Università di Roma, P.le A. Moro 2, Roma I-00185, Italy.
authors: Emanuela
authors: E
authors: Zaccarelli
authors: Dipartimento di Fisica, 'Sapienza' Università di Roma, P.le A. Moro 2, Roma I-00185, Italy.
authors: Francesco
authors: F
authors: Sciortino