To date, it has been generally assumed, based on early experimental work, that ATRP in aqueous dispersed systems is incompatible with anionic surfactants. In the present work, it is clarified that this incompatibility originates in the anionic surfactant (sodium dodecyl sulfate, SDS) displacing the halide ligand from the Cu II bromide-based deactivator, converting it to a Cu II complex, unable to deactivate radicals. This results in a very high polymerization rate as well as essentially no control over the molecular weight distribution. It is demonstrated how such loss of deactivator can be minimized by the addition of a source of halide ions, thus enabling one to conduct ATRP in aqueous dispersed systems using commonly available and inexpensive anionic surfactants such as SDS.

In this communication, we report the successful synthesis of gradient morphology nanoparticles composed of poly(styrene-co-methyl methacrylate) and their characterisation using X-Ray Photoelectron Spectroscopy (XPS).

Miniemulsion polymerization of styrene based on the in situ surfactant-generation technique has been investigated for a range of carboxylic acids and counterions. This technique relies on in situ formation of the surfactant at the oil-water interface and circumvents the use of traditional high-energy mixing (for example, ultrasonication) for generation of the initial miniemulsion. Miniemulsion polymerizations have been conducted successfully using the carboxylic acids lauric acid, palmitic acid and oleic acid, respectively. Coagulation/phase separation was not observed and the number-average particle diameters were o100 nm. The counterions K + , Na + and Li + were investigated in combination with five different carboxylic acids (all permutations), revealing that satisfactory miniemulsion formation/stability could only be obtained with K + . Results of miniemulsion polymerizations conducted in the presence of an aqueous-phase radical scavenger were consistent with predominant monomer droplet nucleation. Use of the corresponding preformed surfactants added to the aqueous phase, without high-energy mixing, did not result in sufficiently stable initial (before polymerization) miniemulsions.