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 t1/3. 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.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces