Mixtures of organocobalt chelates as initiators of emulsion polymerization of styrene

The emulsion polymerization of styrene has been investigated in the presence of the mixture of alkylcobalt(III) chelates with a tridentate Schiff base containing linear or branched alkyl ligands and characterized by different decomposition constants. The addition of as low as 10 wt % of the complex with the isopropyl ligand to the mixture has been shown to decrease the induction period by a factor of 5 compared with the ethylcobalt complex. The optimal mass ratio between organic cobalt complexes containing isopropyl and ethyl ligands is 1: 3. It has been established that the use of a pair of initiators containing alkyl ligands of different structures, with one of them (more active) efficiently initiating the polymerization at the initial stage and the other (with a lower decomposition rate constant) providing the presence of free radicals in the reaction zone until complete conversion of the monomer, makes it possible to carry out the process to high conversions (>99%) within the optimal period.