In situ 1H nuclear magnetic resonance (NMR) spectroscopy has been used to directly investigate the processes that occur during the early stages (typically the first few monomer addition
steps) of an AIBN-initiated RAFT polymerization of styrene in the presence of the RAFT agent
(DMP) at 70, 75 and 80 respectively. The change in concentration of these important species as a
function of time has been investigated. It was found that the reaction was extremely selective during the period of consumption of the initial RAFT agent. Two addition-fragmentation processes with different activation rate constants kact were observed from the NMR spectra. The fast first-order process with 1kact of 0.120, 0.173 and 0.487 min-1 at 70, 75 and 80°C respectively and activation energy of 17.0 kJ /mol is followed by a slow pseudo-zero-order process. We recently apply RAFT to synthesize the water-soluble polymers and block copolymers in water at room temperature. The in situ NMR has been used to monitor the all species evolution from time 0 to almost 100% conversion. The molecular weights are also monitored in situ using DOSY, diffusion-ordered 2d NMR-spectroscopy. The novel results about the in situ NMR studies of the synthesis of the 12 water soluble monomers, 5 no ionic, 3 anionic and 4 cationic, as well as 8 triblocoplymers will be presented.
