Molecular weights of PMMA beads synthesized by emulsifier-free emulsion polymerization

Uniform sized poly(methyl methacrylate)(PMMA) beads were prepared by soapless emulsion polymerization using methacrylate monomer and potassium persulfate as monomer and initiator, respectively. The molecular weights and the morphology of resulting latexes were determined by means of GPC and SEM in terms of the reaction conditions such as the reaction temperature, the amount of the initiator and the solid content. The molecular weights of the latex beads were found to be decreased with increasing amount of initiator and the reaction temperature, and no dependency of the solid content. The sizes of the prepared beads varied between 0.3 and 0.6 μm with the reaction conditions; the lower the reaction temperature, or the higher the initiator concentration and the solid content, the larger the particle sizes were observed. The relationship between the particle size and the initiator concentration is controversial to that in the case of the crosslinked polymer beads. High molecular weight of 10⁶g/mol PMMA bead was able to obtain not only with 0.5 wt% of initiator at 60 °C but also with 0.2 wt% of initiator at 80 °C.