Synthesis of uniform polymer microspheres with "living" character using ppm levels of copper catalyst: ARGET atom transfer radical precipitation polymerisation

The first example of activators regenerated by electron transfer atom transfer radical polymerisation (ARGET ATRP) under precipitation polymerisation (PP) conditions is reported. This new method for polymer synthesis (called ARGET ATRPP) requires only very low levels of metal catalyst for success, a distinctive feature that enables the production of uniform polymer microspheres under reversible-deactivation radical polymerisation control. The influence of the polymerisation conditions (monomer concentration, reaction time, initiator and catalyst concentrations) on the polymerisations and microsphere products were investigated and optimised. The ARGET ATRPP methodology was used to prepare polymer microspheres with narrow particle size distributions and mean particle diameters in the micron-size range, under dilute monomer conditions (2%) whilst using very low copper catalyst concentrations (down to 1.7 ppm). The "living" characteristics of the polymer microspheres enabled poly(methyl methacrylate) brushes to be grafted-from the microspheres directly without the need for any additional surface functionalisation step to immobilise initiator moieties.