Abstract
Charged polystyrene particles, which were initially sedimented uniformly on a glass wall, spontaneously transformed into twodimensional gas, liquid, and solid phases in aqueous solvents. Their relative stabilities could be determined by a common phase diagram consisting of gas-liquid and liquid-solid coexistence lines under the conditions of a large particle radius (a ≫κ -1 ) and intermediate screening length (a=1.5 μm and 10 nm10σ) decay lengths were found. The latter was attributed to the charge density wave (CDW) due to alternating layers of oppositely charged colloids and counterions along the radial coordinate. Because the charged glass wall had a similar surface charge density and sign as the particles, the repulsive levitation at the wall against gravity assisted the thermal rearrangement during phase separation. Further evaluation is promising for investigating the complicated physics of particle-wall interactions.
