In-situ nitroxide-mediated radical polymerization (NMP) processes:: Their understanding and optimization

The field of in-situ nitroxide-mediated radical polymerization (NMP) processes is a hot topic as of late. They are a valuable alternative to the expensive alkoxyamines available on the market. NMP relies on the conversion of readily available and low-cost starting products into mediating nitroxides and alkoxyamines directly in the polymerization medium. In most cases, the mixing of all the components and heating them at the polymerization temperature does not lead to an effective control. In fact, the method consists of premaking the polymerization regulators in the reaction medium before starting the polymerization at a higher temperature. Proceeding further depends on several factors, such as the momoner and precursors of nitroxides, although no rule has popped up. NMP also takes advantage of the fact that the structure of the nitroxides and alkoxyamines formed in situ depends on the structure of both the nitroxide precursor and the free-radical initiator and on the experimental conditions.