Magnetic Effects on Photoinduced Emulsion Polymerization. Effects of Lanthanide Ion Addition

摘要

Photoinduced emulsion polymerization of styrene with sodium dodecyl sulfate (SDS) as the surfactant and dibenzyl ketone (DBK) as an initiator was significantly prevented at O G in the presence of La(3+), Gd(3+), or Mg(++). At 2000 G good yields of high molecular weight polystyrene were obtained in the presence of La(3+) or Mg(++) but polymerization was significantly prevented in the presence of Gd(3+). These results are explained on the basis of a combination of salt effects on micellar structure and magnetic effects on the reactions of geminate triplet radicals in micelles. The presence of salts caused an increase in the size of micelles, which in turn resulted in a reduced efficiency of free-radical escape from the micelles, and the effect of magnetic field on photoinduced emulsion polymerization was counteracted by the presence of Gd(3+). The polymerization of methyl methacrylate was found to be unaffected by the addition of these ions in the absence or presence of external magnetic field.