Crosslinkable functional moiety for the formation of highly crosslinked stable microspheres in the precipitation polymerization

The highly crosslinked stable spherical microspheres were successfully synthesized using styrene and three crosslinking agents having different number of crosslinkable functional moiety in comonomer using the precipitation polymerization. The crosslinking agents are ethylene glycol dimethacrylate (EGDMA), trimethylolpropane trimethacrylate (TMPTMA) and pentaerythritol tetraacrylate (PETRA). The maximum and minimum concentrations for forming the stable spherical particles were ranging at 20–90 mol% for EGDMA, 15–80 mol% for TMPTMA, and 5–40 mol% for PETRA, respectively. The number-average diameter of stable poly(S-co-EGDMA), poly(S-co-TMPTMA), and poly(S-co-PETRA) particles varied 4.1–3.06, 3.94–3.03 and 2.77–1.66 μm, respectively. Since the prepared microspheres are highly crosslinked, no glass transition temperature was observed. The TGA onset point of the thermal degradation temperature increased with the concentration of crosslinking agent and the number of crosslinkable functional moiety, which is EGDMA < TMPTMA < PETRA. As a result, the minimum and maximum concentrations for the formation of stable spherical particles of poly(S-co-EGDMA), poly(S-co-TMPTMA), and poly(S-co-PETRA), the particle size and its distribution, CV, yield and the TGA onset point are significantly affected by the number of the crosslinkable functional moiety. Thus, the number of the crosslinkable functional moiety and the different reactivity as well as the different copolymerization parameters of styrene with (meth)acrylates would influence the composition as well as the rate of formation of stable microspheres.