Macrocyclic polyether phase transfer catalysts for free radical polymerization of acrolein

Macrocyclic polyethers, e.g., crown ethers and cryptands, were prepared and employed as phase transfer catalysts for free radical polymerization of ac rolein, a vinyl monomer, with persulfates (S2O82-) as initiators. The catal ytic abilities of various macrocyclic polyethers as catalysts for the free radical polymerization of acrolein were found to be in the oder: benzo-15-c rown-5 > dibenzo-18-crown-6 > 12-crown-4 > 15-crown-5 > 18-crown-6 > crypta nd-22 with sodium persulfate (Na2S2O8) as initiator. Sodium persulfate prov ed to be a better initiator than ammonium persulfate or potassium persulfat e with benzo-15-crown-5 as a catalyst. Effects of solvents and temperature on the catalytic polymerization were also investigated. The polymerization rates in various solvents were in the order: dioxane > benzene > acetonitri le > acetone > dichloro methane > hexane > water. Comparison between bulk p olymerization and solution polymerization was also made. Higher polymerizat ion rate was observed at higher temperature. The molecular weights of polya crolein and the conversion of monomer in reaction period were determined wi th gel permeation chromatography and ultra-violet spectrophotometry, respec tively. Concentration effects of crown ether and initiator were also invest igated and discussed.