Magnetite nanoparticles for the preparation of ultrapure RAFT polymers
Magnetic nanoparticles (MNP) and the application of a strong external magnetic fields were used to separate living chains from dead chains prepared by the reversible addition-fragmentation chain transfer (RAFT) process, by using Z-functional RAFT agents that are strongly attracted to the MNP surface. The MNP dispersion was mixed with a 32% HCL solution and the organic phase containing the oleic acid and the polymer was extracted and dried to give the extracted polymer. The RAFT functional chains in the unextracted polymer result from the ligand exchange process in the extraction step, which does not attach all RAFT functional chains to the MNP surface. The results also show that the extension data for the unextracted polymer show a significant fraction of high M polymer that apparently contains some RAFT groups.