Adhesion between submicrometer polystyrene spheres

The sphere–substrate contact method was usually used to study adhesion theory because it is rather difficult to make two micrometer or submicrometer spheres contact precisely. Here, we used sphere–sphere contact method by a novel, simple process to investigate deformations of spheres. The polystyrene particles size ranges from 60 nm to 600 nm. We found that the polystyrene particles underwent plastic deformations due to van der Waals interaction. The contact radii were observed by the scanning electron microscope (SEM).