Long-range Attraction between Like-charged Colloids: Simulations and Microgravity Experiments

Deionized dilute charged colloidal systems exhibit gas-liquid and gas-solid coexistence and re-entrant transitions depending on suspensions parameters such as volume fraction, charge density and ionic strength. These observations constitute evidence for the existence of long-range attraction between like-charged colloids. Monte Carlo (MC) simulations using Sogami-Ise pair-potential, which has a long-range attractive term, could explain the above mentioned experimental observations. MC simulations, which correspond to zero gravity conditions, revealed coexistence of liquid-like droplet with rare phase (gas-like) and voids coexisting with dense (solid-like) phase clusters. These predictions will be verified by the project of microgravity experiments in space and the outcome is expected to provide evidence for the existence of long-range attraction between like charged colloids.