Size and uniformity variation of poly(MMA-co-DVB) particles upon precipitation polymerization

Abstract

Stable poly(methyl methacrylate-co-divinylbenzene) (poly(MMA-co-DVB)) microspheres were prepared by precipitation polymerization using acetonitrile as the main medium under various polymerization conditions, including modifications of the agitation speed, monomer and initiator concentrations, DVB content in the monomer mixture, and the use of various cosolvents. Gentle agitation was required to obtain smooth spherical particles. The individually stable microspheres were obtained at monomer concentrations of up to 15 vol% in an acetonitrile medium. The number-average diameter increased linearly with respect to increases in the monomer and initiator concentrations. We found, however, that the uniformity of the microspheres was independent of the variation of the polymerization ingredients because nuclei formation was solely influenced by the crosslinking reaction of the monomers. We obtained higher yields for the polymerization at higher concentrations of monomer and initiator. The concentration of DVB in the monomer mixture composition played an important role in determining not only the size of the microspheres but also the yield of the polymerization. In addition, although we employed various cosolvents as the polymerization medium, we found that acetonitrile/2-methoxyethanol was the only system that provided spherical particles without coagulation. This finding indicates that the precipitation polymerization is strongly dependent on the solvent used as the medium.

Synthesis of poly(acrylamide‐co‐divinylbenzene) microspheres by precipitation polymerization

“…The maximum yield of 70% in poly (AAm-co-DVB) with 75 mol % DVB in the precipitation polymerization was slightly lower than that of other copolymer systems such as poly(MMA-co-DVB) and poly(St-co-DVB), which showed 90 and 89%, respectively. 21,23 Because the yield of the polymerization was at maximum 70% in this system, the remaining 30% was confirmed to stay in the medium as a sol part.…”

“…[poly(MMA-co-DVB)], [20][21][22] and poly(styrene-co-divinylbenzene) [poly(St-co-DVB)]. 23 In addition, mechanistic studies to elucidate the formation of stable microspheres in the absence of any stabilizer have been reported 24,25 in which the absorption of oligomeric species onto the nuclei and the high degree of crosslinking are the primary reasons for the formation and stable growth of the microspheres.…”

“…For example, neat microspheres were prepared above 5 and 20 mol % DVB concentrations in poly(St-co-DVB) and poly(MMA-co-DVB) systems, respectively. 21,23 Stable polystyrene/polyacrylamide (PAAm) microspheres were successfully synthesized below a 10 wt % concentration of crosslinkable monomers such as DVB and ethylene glycol dimethacrylate with the SPG membrane technique. 28 However, a high degree of crosslinking is essential to give coagulum-free microspheres in precipitation polymerization because the formation of stable particles is achieved by means of the crosslinking reaction in the absence of any stabilizer.…”

Effect of co-initiator on the size distribution of the stable poly(styrene-co-divinylbenzene) microspheres in acetone/water mixture

“…14 Up today, the synthesis of highly crosslinked polymers using various self-crosslinkable monomers have widely been studied; poly(divinylbenzene) [P(DVB)], 15,16 poly(methacrylic acid-co-polyethylene oxide methyl ether methacrylate), 17 poly(methacrylate-co-DVB), 18 poly(chloromethyl styrene-co-DVB), 19 poly(DVB-co-maleic anhydride), 20 poly(methyl methacrylate-co-DVB), 8,21,22 poly(styrene-co-DVB) [P(St-co-DVB), 23 poly(acrylamide-co-DVB) 24 and poly(glycidyl methacrylate-co-DVB). 25,26 In addition, mechanistic studies to elucidate the formation of stable microspheres in the absence of any stabilizer have been reported.…”

“…18 Furthermore, acetonitrile is reported to be the only solvent for preparing crosslinked polymer particles in the precipitation polymerization. 21,27 Much effort has paid to find other solvents instead of acetonitrile in the precipitation polymerization, which is one of expensive and environmentally unfriendly solvent. It was first reported that the stable P(St-co-DVB) spherical particles of 1.64~4.02 µm in diameter were prepared using acetone/methanol mixture medium and V-65 as an initiator at 53 o C in the precipitation polymerization.…”