Gas-Liquid-Solid Condensation of Gravitationally Confined Polystyrene Particles near a Charged Wall at Intermediate Screening Lengths

DOI:10.15011/ijmsa.32.320207
Int. J. Microgravity Sci. Appl. 2015p320207
Author
M. ISHIKAWA, S. ITO, S. MIYOSHI and J. HABASAKI
Organization
RIKEN, Research Cluster for Innovation,Sysmex Corp. Ltd., MRI Research Associates, Inc., Tokyo Institute of Technology
Abstract
Charged polystyrene particles, which were initially sedimented uniformly on a glass wall, spontaneously transformed into two-dimensional 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 nm<κ-1<300 nm), where a is the particle radius and κ is the Debye-Hückel parameter. The gas-liquid miscibility gap which had a critical point was very stable over a wide range of salt concentrations. The radial distribution functions of colloidal particles in the liquid phase showed remarkable oscillatory damping and both short-range (~particle diameter σ) and long-range (>10σ) 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.
Keyword(s)
Polystyrene, Charged colloid, Colloidal phase transition, Sedimentation.
PDF
Download

Received 12 Jan. 2015, accepted 31 Mar. 2015, published 31 Apr. 2015

© The Japan Society of Microgravity Applicaiton

この投稿文は次の言語で読めます: Japanese

ページ先頭に戻る