Harnessing the Interaction between Surfactant and Hydrophilic Catalyst To Control eATRP in Miniemulsion

The catalytic system was generated in situ by mixing commercially available reagents to show that miniemulsion atom transfer radical polymerization (eATRP) can be carried out with an anionic surfactant and a single, strongly hydrophilic catalyst. Only a few ppm of catalyst were present inside the monomer droplets. Polymer purification was simplified because, after crashing the miniemulsion, >99% of the hydrophilic catalyst was present in the aqueous phase. Controlled polymerization was favored by the strong interaction between copper complexes and an anionic surfactant, sodium dodecyl sulfate (SDS). This interaction, once considered a poison for the ATRP catalyst, generated hydrophobic ion pairs at the droplet surface that transported a fraction of the catalyst into the monomer droplets, enabling controlled polymerization via ion-pair catalysis. Control was further enhanced by catalyst bound to the droplets surface via interfacial catalysis.