| DESCRIPTION |
One of the most efficient, powerful, versatile, simple, and inexpensive controlled radical polymerization processes, according to author. is atom-transfer radical polymerization (ATRP). This process is tolerant of trace impurities, including water and oxygen, and has been used to polymerize monomers such as acrylates, methacrylates, styrenes, acrylonitrile, and vinyl pyridine. ATRP typically employs an alkyl halide as an initiator and a transition-metal complex as a catalyst to create a polymer radical. A bipyridine complex of a copper(I) bromide or chloride is commonly used as the catalyst. The polymer radical grows until it is deactivated to form a dormant species containing a terminal halogen atom. Reactivation of the dormant polymer allows the polymer chain to resume its growth until it is deactivated again. THE VERSATILITY of ATRP arises because the initiators may also contain amino, hydroxy, epoxy, and other useful functional groups. "Many multifunctional initiators enable the polymeric chains to grow in several directions leading to star, comb, brush, or other structures. In addition, the terminal halogen can easily be displaced by various nucleophiles such as azides or phosphines, providing more functional terminal groups."
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