Use of a Lewis Acid Surfactant Combined Catalyst in Cationic Polymerization in Miniemulsion: Apparent and Hidden Initiators

A Lewis acid surfactant combined catalyst (LASC) was tentatively used in a cationic polymerization in miniemulsion of p -methoxystyrene ( p MOS). In a first part, the initiating potential of trisdodecyl sulfate ytterbium (Yb(DS) 3, 0.25H 2 O) was evidenced in the solution polymerization of p MOS initiated by the corresponding chlorinated adduct p MOS−HCl. Miniemulsion polymerizations of p MOS performed using the same initiating system gave rise to oligomers, but experimental conditions chosen could not evidence the expected LASC-mediated cationic polymerization process. Further studies showed that LASC is located at the interface and acts only as a surfactant together with SDS. The polymerization occurred due to the hydrolysis of p MOS−HCl. The resulting acidification of the water phase leads to the transformation of SDS into its sulfuric acid form acting as an inisurf according to an interfacial cationic polymerization process. Latex particles of p MOS incorporating narrowly distributed low molar mass chains were obtained.