title: Dynamics of concentrated hard-sphere colloids near a wall.
abstract: We investigate the Brownian motion of hard-sphere colloids near a solid wall by Evanescent Wave Dynamic Light Scattering (EWDLS). We carried out measurements for various volume fractions of sterically stabilized poly(methyl methacrylate) (PMMA) particles over a range of scattering wave vectors, q. While in the dilute regime, the near wall short-time diffusion is significantly slowed down due to particle-wall hydrodynamic interactions (HI); as volume fraction increases, the wall effect is progressively diminished at all q's. We present a new analysis for the EWDLS short-time self- and collective diffusivities applicable to all volume fractions and a simple model for the self-diffusion describing the interplay between particle-wall and particle-particle HI. Moreover, a weaker decay of the near-wall self-diffusion coefficient with volume fraction is predicted by Stokesian dynamics simulations.
authors.affiliation: FORTH/IESL and Department of Material Science & Technology, University of Crete, 71110, Heraklion, Greece.
authors.forename: V N
authors.initials: VN
authors.lastname: Michailidou
authors.forename: G
authors.initials: G
authors.lastname: Petekidis
authors.forename: J W
authors.initials: JW
authors.lastname: Swan
authors.forename: J F
authors.initials: JF
authors.lastname: Brady
mesh_terms: D003102:Colloids / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012542:Scattering, Radiation; D013499:Surface Properties
chemical_list: D003102:Colloids; D019904:Polymethyl Methacrylate