(481d) Synthesis of Spherical and Anisotropic Polymer Colloids with Nanoscale Surface Topography

Particle roughness has recently emerged as an important design parameter to engineer the bulk and interfacial properties of colloidal suspensions and monolayers. However, most prior work focuses on the impact of particle roughness on the behavior of spherical colloids. In this presentation, we describe a synthetic approach to synthesize spherical and ellipsoidal shaped polymer colloids with controlled nanoscale surface topography. Three classes of particles are created: homogeneous particles with smooth surfaces, chemically heterogeneous colloids with nanoscale roughness, and chemically homogeneous colloids with nanoscale porosity. Non-crosslinked linear polystyrene spheres are used in seeded emulsion polymerization (SEP) with tert-butyl acrylate monomer. Reaction conditions are chosen such that the subsequent polymerization induced phase separation results in spherical particles that possess kinetically trapped domains of poly-tert-butyl acrylate, giving the particles a rough surface. The domains may then be removed via acid catalyzed hydrolysis to form porous particles. Traditional mechanical stretching can be performed on rough spheres, producing rough and porous ellipsoids. The precise nature of the surface topography can be controlled by tuning initiator concentration, introducing cosolvents, or changing the amount of comonomer added. As an outlook, we discuss the potential applications of using these particles in the creation of ordered interfacial monolayer materials.