Long-ranged attraction between charged polystyrene spheres at aqueous interfaces.
We report an optical and atomic force microscopic study of interactions between charged polystyrene spheres at a water-air interface. Optical observations of bonded particle clusters and formation of circular chainlike structures at the interface demonstrate that the interaction potential is of dipole origin. Atomic force microscope phase images show patchy domains on the colloidal surface, indicating that the surface charge distribution is not uniform as is commonly believed. Such surface heterogeneity introduces in-plane dipoles, leading to an attraction at short interparticle distances.
Chen
Wei
W
Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Tan
Susheng
S
Ng
Tai-Kai
TK
Ford
Warren T
WT
Tong
Penger
P
D003102:Colloids / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D011137:Polystyrenes / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D003102:Colloids; D011137:Polystyrenes; D014867:Water