title: Surface heterogeneity of polystyrene latex particles determined by dynamic force microscopy.
abstract: Atomic force microscopy (AFM) was employed to characterize the surface chemistry distribution on individual polystyrene latex particles. The particles were obtained by surfactant-free emulsion polymerization and contained hydrophilic quaternary ammonium chloride, sodium sulfonate, or hydroxyethyl groups. The phase shift in dynamic force mode AFM is sensitive to charge/chemical interactions between an oscillating atomic force microscope tip and a sample surface. In this work, the phase imaging technique distinguished phase domains of 50-100 nm on the surfaces of dried latex particles in ambient air. The domains are attributed to the separation of ion-rich and ion-poor components of the polymer on the particle surface.
authors.affiliation: Department of Chemistry, Oklahoma State University, Stillwater, OK 74078, USA. tsushen@okstate.edu
authors.forename: Susheng
authors.initials: S
authors.lastname: Tan
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sherman
authors.forename: Dongqi
authors.initials: D
authors.lastname: Qin
authors.forename: Warren T
authors.initials: WT
authors.lastname: Ford