Thermally Robust Highly Crosslinked Poly(methyl methacrylate-co-divinyl benzene) Microspheres by Precipitation Polymerization

We prepared thermally robust fully crosslinked poly(methyl methacrylate-co-divinyl benzene) ［poly(MMA-co-DVB)］microspheres successfully by precipitation polymerization in the absence of a stabilizing agent. The DVB concentration plays a pivotal role not only in the formation of the individually stable microspheres but also in the polymerization characteristics, including the particle size, the uniformity of size, the polymerization yield, and the thermal properties. The number-average diameter of the microspheres increased linearly, from 0.72 to 2.15 $\mu\textrm{m}$, and the particle size distribution became narrower, by elevating the uniformity from 1.35 to 1.12, as the DVB concentration increased from 20 to 75 mol%. In addition, the yield of the polymerization increased, from 73.4 to 98.6%, as the DVB concentration increased. Since the prepared particles possess fully crosslinked microstructures, no glass transition temperatures were observed, but all the samples prepared with DVB concentrations ranging from 20 to 75 mol% possess enhanced thermal properties. Based on the DSC and TGA data, the thermal stability of the mesospheres prepared by the precipitation polymerization is significantly improved as a result of crosslinking with DVB.