Morphology control of poly(methyl methacrylate) particles via seeded dispersion polymerization

Nonspherical polymer particles have been studied for several decades because their properties, such as mechanical and optical properties, differ from those of spherical particles. Their potential in advanced applications has continued to drive interest in developing shape-controlled synthesis methods. In this study, we investigated the shape control of poly(methyl methacrylate) (PMMA) particles during seeded dispersion polymerization (SDP) of styrene using PMMA as seed particles in the presence of various hydrocarbons. By systematically varying the polymerization temperature ( T r ) and hydrocarbon type, we successfully fabricated PMMA particles with diverse morphologies, specifically golf ball-like, bowl-like, and barrel-like structures. Results revealed that the difference between T r and the glass transition temperature ( T g ) of the seed particles ( T r − T g ) plays a critical role in determining the particle shape. Furthermore, an index was formulated based on Hansen solubility parameters to quantify the affinity differences between the seed and second polymers for the medium, which helped explain the behavior of the second polymer domain during polymerization. The use of a hydrophilic initiator suppressed the submergence of domains into the seed particle, facilitating the formation of polyhedral and disk-like particles. This paper contributes to the development of a generalized strategy for the synthesis of shape-controlled nonspherical polymer particles via SDP.