ATRP or Atom Transfer Radical Polymerization is a polymerization reaction involving free radicals. It was introduced as an extension to ATRA or Atom Transfer Radical Addition by Jin-Shan Wang et al, (1995) and Mitsuo Sawamoto et al. (1994/5). As a living radical polymerization which is a form of living polymerization, it allows the reaction to be carried out in a controlled way, and can be used to obtain polymers with high molecular weight and low polydispersity index.
This control result from the use of a transition metal based catalyst. This catalyst provides an equilibrium between active, and therefore propagating, polymer and an inactive form of the polymer; known as the dormant form. Since the dormant state of the polymer is vastly preferred in this equilibrium, side reactions are suppressed.
By lowering the concentration of radicals, termination is suppressed and control is achieved.
