title: Controlled flats on spherical polymer colloids.
abstract: Colloidal particles with heterogeneous surfaces offer rich possibilities for controlled self-assembly. We have developed a method for preparing micrometer-sized polystyrene spheres with circular flat spots of controlled radius and location. The flats are created by settling the particles onto a flat glass substrate and then raising the temperature above the glass-transition temperature of the polymer for a controlled time (t). The polymer particle spreads on the glass such that the radius of the flat grows with time. We present a scaling theory for the hydrodynamics of the flattening process, finding that the radius of the flat grows as t(1/3). The model is in good agreement with our experimental observations of the flat radius versus spreading time as well as with previous studies in the literature for sintering polymer spheres.
authors.affiliation: Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Laura Mely
authors.initials: LM
authors.lastname: Ramírez
authors.forename: Scott T
authors.initials: ST
authors.lastname: Milner
authors.forename: Charles E
authors.initials: CE
authors.lastname: Snyder
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Colby
authors.forename: Darrell
authors.initials: D
authors.lastname: Velegol
mesh_terms: D003102:Colloids / Q000138:chemical synthesis / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D008956:Models, Chemical; D010316:Particle Size; D011137:Polystyrenes / Q000138:chemical synthesis / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D003102:Colloids; D011137:Polystyrenes