Reducing Copper Concentration in Polymers Prepared via Atom Transfer Radical Polymerization

Three different initiation systems for atom transfer radical polymerization (ATRP): normal ATRP, activators regenerated by electron transfer (ARGET) ATRP, and initiators for continuous activator regeneration (ICAR) ATRP were used to synthesize polystyrene with a number-average molecular weight approximate to 20 000 g . mol(-1). Each polymerization mixture was divided and subjected to one or more purification methods including passing through a column filled with neutral alumina, stirring with an ion exchange resin (ATRP Pure), or precipitation into hexanes or methanol. Inductively coupled mass spectrometry was used to analyze the concentration of copper in each sample. For the polystyrene prepared by normal ATRP, purification by a neutral alumina column was the most effective at removing copper (down to 2 parts per million by mass). For the ARGET and ICAR ATRP, purification by a neutral alumina column and stirring with 10 wt.-% ATRP Pure gave comparable results (each approximate to 1 part per million by mass).