Polymerization of ethylenically unsaturated monomers employing catalyst of aliphatic .alpha.-(hydroperoxy)azo compounds and salts thereof

In a process for the homo- or copolymerization of ethylenically unsaturated monomers which are responsive at suitable temperatures to free radical generators as polymerization initiators, the improvement which comprises employing as the free radical generator a compound of the formula ##STR24## wherein:

• M is selected from the group consisting of hydrogen, alkali metal and alkaline earth metal;
• m is the valence of M;
• R is selected from the group consisting of C.sub.1 - C.sub.12 alkyl, C.sub.3 - C.sub.12 cyclo-, bicyclo- or tricycloalkyl, and C.sub.7 - C.sub.9 aralkyl;
• R.sub.1 and R.sub.2 are separately selected from the group consisting of hydrogen, C.sub.1 - C.sub.8 alkyl, C.sub.3 - C.sub.12 cyclo-, bicyclo- or tricycloalkyl, C.sub.7 - C.sub.12 aralkyl, C.sub.6 - C.sub.14 aryl and 5 - 6 membered heterocyclic wherein the hetero atom is O, S or N, and R.sub.1 and R.sub.2 taken together form C.sub.3 - C.sub.7 alkylene;
• and
• one or more of each of R, R.sub.1 and R.sub.2 can be substituted with a member selected from the group consisting of lower alkoxy, hydroxy, lower alkoxycarbonyl, lower acyloxy, halogen, cyano, dimethylamido and lower alkylsulfonato.