Cyanoxyl-mediated free-radical polymerization of acrylic acid: Its scope and limitations

Abstract

This work examines the scope and limitations of the cyanoxyl (·OCN)-mediated free-radical polymerization of acrylic acid (AA) with respect to the criteria of livingness. Cyanoxyl persistent radicals were generated in situ through the reaction between arenediazonium salts (XC6H4NN⊕BF, where X is H, OCH3, Cl, or NO2) and sodium cyanate (NaOCN). This article thoroughly discusses the role played by such oxygen-centered radicals in the polymerization process; it particularly focuses on the influence of the concentration and nature of the diazonium salt, the solvent, and the temperature on features such as the variations of ln([M]0/[M]) versus time (where [M]0 is the initial monomer concentration and [M] is the monomer concentration), the number-average molar mass versus conversion, and the polydispersity versus conversion in cyanoxyl-mediated free-radical polymerizations of AA. Cyanoxyl-terminated samples were used as macroinitiators for the polymerization of methyl methacrylate to generate poly(acrylic acid)-b-poly(methyl methacrylate) block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 519–533, 2005