Combination of potassium ferricyanide, diazothio ether and mercaptan as “catalyst” for emulsion polymerizations of butadiene and styrene

The combination of a diazothio ether and a mercaptan in an emulsion copolymerization recipe of butadiene and styrene containing potassium ferricyanide as a “catalyst” has a very strong activating effect on the polymerization. p‐Methoxyphenyl diazothio‐(2‐naphthyl) ether, designated as MDN, was found to be particularly suitable. In the present paper, ordinary household soap (S.F. flakes) and dehydrogenated rosin soaps of varying degrees of purity have been used as emulsifiers. By using various tertiary or primary mercaptans, polymers of any degree of modification were obtained. The recommended recipe at 40°C. gives about 80% conversion in 10 hours. The rate of conversion is greatly increased by adding to the recipe substances which have a strongly alkaline reaction in water, as sodium carbonate, trisodium phosphate, or sodium hydroxide. With such “alkaline” recipes attractive rates of conversion are obtained at around 0°C.