temperature was 18 8 u00b0 c in a 0 5 l 4 necked round bottom flask fitted with mechanical stirrer reflux condenser thermometer dropping funnel and nitrogen inlet were charged 1 4 gr sds sodium dodecyl sulfate and 100 ml of water the flask was immersed in an oil bath and heated to 70 u00b0 c with continuous stirring 250 rpm nitrogen was introduced under the surface of the liquid after 1 hr the nitrogen inlet was raised above the surface of the liquid and 0 15 gr of k 2 s 2 o 8 were added 5 min later a solution of 18 2 gr styrene and 5 8 gr acylonitrile was added dropwise over 30 min the emulsion pre polymerization was continued for another 20 min after which 8 5 gr of a pbbma suspension u02dc 60 solids were added dropwise over 40 min a second portion of 0 15 gr of k 2 s 2 o 8 was added 3 hr after the addition of the suspension was finished the polymerization was continued overnight a stable latex stable for at least one month was obtained the terpolymer isolated from this emulsion was characterized the bromine content was 12 5 the nitrogen content was 5 and the glass transition temperature was 107 u00b0 c the molecular weight depends on the polymerization conditions in this particular case a weight average molecular weight mw of 1 2 10 6 and number average molecular weight mn of 422 000 was determined in dimethylformamide solution calibrated with polystyrene standards the suspensions of the invention are useful for a.