Nitroxide-mediated living radical polymerization in dispersed systems

Living/controlled radical styrene miniemulsion polymerizations mediated by the nitroxide TEMPO were run at 135 °C. A coordinated experimental and modelling program has shown that preserving livingness in these systems involves finding an optimum solution between loss of livingness due to biradical termination and loss due to disproportionation. Long reaction times lead to greater dead chain formation through disproportionation, while high reaction rates can result in high biradical termination rates. Hexadecane-free runs were found to give >95% conversion in <3 hours while maintaining polydispersities ∼1.3, but only at high concentrations of the surfactant SDBS.