Steric stabilization of polystyrene colloids using thiol‐ended polyethylene oxide

Thiol‐ended polyethylene oxide (I) has been prepared from the esterification of thioglycolic acid with monomethylether of polyoxyethylene glycol. Emulsion polymerization of styrene (and, in a few cases, methylmethacrylate as comonomer) was carried out in the presence of I using either water‐soluble azo initiator or t‐butylhydroperoxide. In the former case, bimodal particle size distribution was obtained while monodisperse latexes could be prepared in the latter case. Then a redox system was formed from I and t‐BuOOH so that I was both an initiator and a transfer agent. Good steric stabilization of the latexes was observed. The polyethylene oxide sequence of I was partly incorporated at the surface of the latex particles, but the incorporation yield remained limited (between 7 and 18%). Most of the resdue of I remained in the serum.