Emulsion polymerization of butadiene, 4. Effect of thiols

Abstract

Abstract The role of thiols of low water solubility, commonly used in the emulsion polymerization of butadiene, has been considered. The following effects have become apparent: (1) dodecanethiols act as efficient chain transfer agents in limiting the formation of heavily cross‐linked polymer networks; (2) the monomer concentration within the particles is not influenced by such thiols; (3) C 12 ‐thiol radicals do not desorb because of their extremely low water solubility. The ‘promoting effect’ of thiols in emulsion polymerizations of diene‐hydrocarbons is still poorly understood, but it appears to be related to impurities present in the emulsifier, as it was found completely absent in emulsifier‐free polymerizations.