Polymerization long chain mercaptans

Nomura (25) investigated the effect of carbon tetrabromide, carbon tetrachloride and long chain mercaptans on the kinetics of emulsion polymerization of styrene. In the case of CBr and CCl the effect on the polymerization was attributed to desorption of the small chain transferred radicals. Similar results were obtained by Napper et al (26). Nomura also observed that the long chain mercaptan (n- dodecyl mercaptan) did not affect the number of particles and the rate, presumably due to the water-insolubility of the chain transferred radicals. 

It should be noted that in the case of water-insoluble long chain mercaptans, the thermodynamic effect as in the case with n-octadecane, may also depress the rate. Similar effects may be anticipated in emulsion copolymerizations, and polymerizations involving several monomers where one or more are highly water-insoluble. These effects would then be superimposed on the other variables of the polymerization. 

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