Grafting Polymer Chains Bearing an N-Succinimidyl Activated Ester End-Group onto Primary Amine-Coated Silica Particles and Application of a Simple, One-Step Approach via Nitroxide-Mediated Controlled/Living Free-Radical Polymerization

In a first part, the alkoxyamine initiator derived from BlocBuilder (R) based on the nitroxide SG1 and bearing an N-succinimidyl ester function was used to synthesize a variety of well-defined polymers with the activated ester group at the alpha-end. The grafting of those polymer chains onto primary-amine functionalized Stober silica particles was performed in soft conditions at room temperature and was studied as a function of the polymer chain length, the type of solvent, and the concentrations of both polymer and amine. Polymer grafting densities were mainly in the 0.1-0.2 chain nm(-2) range. To increase the grafting density in simple experimental conditions, a direct one-step method was then proposed: the primary-amine modified silica, the N-succinimidyl ester functionalized alkoxyamine, and the monomer were all introduced into the reaction medium at once. This technique allowed grafting and chain growth to take place simultaneously at the polymerization temperature (i.e., 120 degrees C for styrene), in a single step, and produced hybrid particles with very high grafting density, up to 0.9 chain nm(-2), and long polymer chains. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 173-185, 2010