Nitroxide-Mediated Copolymerization of Methacrylic Acid and Sodium 4-Styrenesulfonate in Water Solution and One-Pot Synthesis of Amphiphilic Block Copolymer Nanoparticles

The SG1-mediated copolymerization of methacrylic acid and a small percentage of sodium 4-styrenesulfonate was performed in water solution at 76 °C, using BlocBuilder as an alkoxyamine initiator under acidic conditions. Unexpectedly, these conditions, which could be considered as rather unfavorable due to the instability of SG1 in acidic water, led to very good results in term of polymerization kinetics and control over polymer chain growth. It appeared that low temperature and short reaction time were the key parameters to maintain a good living character to the chains as evaluated by in situ 31P NMR. The aqueous system was then used directly as the polymerization medium for the emulsion copolymerization of methyl methacrylate and styrene performed at 90 °C. This one-pot procedure led to the synthesis of amphiphilic block copolymers that self-assembled into stable core–shell nanoparticles.