Synthesis of poly (p‐methylstyrene) ‐ graft‐poly (oxyethylene) and application as a polymeric surfactant in emulsion polymerization

Poly(p‐methylstyrene)‐graft‐poly(oxyethylene) copolymers were prepared from p‐methylstyrene and æ‐hydroxy‐ω‐methyl‐poly(oxyethylene) using a ‘grafting on to’ technique. A total of 10 copolymers were synthesized varying in the hydrophobic back bone chain lengths, hydrophilic branch lengths and frequency of branches. The stabilizing efficiency of these amphipathic copolymers was studied in the emulsion polymerization of styrene. Using the number, size and size distribution of the particles as the criterion of stability, it was found that the polyoxyethylene (PEO) chain length is not as crucial for stability as the availability of the backbone for anchoring. A change in the backbone chain length (from M̄n = 1000 to 24000) with the same percent PEO had no effect on the outcome of the reaction: the latices stabilized to the same number of particles of the same size.