Crown Ether As The Phase‐Transfer Catalyst for Free Radical Polymerization of Hydrophobic Vinyl Monomers

Abstract

AbstractVarious crown ethers were used as phase‐transfer catalysts for free radical polymerizations of some water‐insoluble vinyl monomers such as acrylonitrile, methylmethacrylate and styrene with persulfate as initiator. The catalytic abilities of these crown ethers for free radical polymerization of acrylonitrile with S2O82−ion as an initiator were in the order: 18‐crown‐6 > 15‐crown‐4 > 12‐crown‐4 > benzo‐15‐crown‐5 > dibenzo‐18‐crown‐6. Among various persulfates such as Na2S2O8 K2S2O8 and (NH4)2S2O8, ammonium persulfate was the optimum initiator for the polymerization of acrylonitrile catalyzed by 18‐crown‐6 or 15‐crown‐5. Among the organic solvents used, chloroform seems to be the best solvent for the catalytic polymerization of acrylonitrile. An apparent activation energy of 72.9 kJ mol−1 was observed for the polymerization of acrylonitrile. The catalytic reaction rates of free radical polymerization for these hydrophobic vinyl monomers were in the order: acrylonitrile > methylmethacrylate > styrene > isoprene. Effects of concentrations of crown ether, initiator, and nitrogen on the polymerization of these vinyl monomers were investigated.