In-situ Functionalisation in Nitroxide Mediated Polymerisation: A Novel and Efficient Switch from NMP to ATRP

LIONEL PETTON; ANDRÉS CIOLINO; BART DERVAUX; FILIP DU PREZ

Conferencia; IUPAC 9th International Conference on Advanced Polymers via Macromolecular Engineering; 2011

Nitroxide Mediated Polymerisation (NMP) is one of the main methods for Controlled Radical Polymerisation (CRP). The advantages of NMP are its ease of use, tolerance to most functional groups and its versatility. However, as NMP proceeds through the reversible addition of a stable radical onto the propagating chain-end at higher temperature, this implies that the end product will conserve the nitroxide end-group. Because polymers are usually processed at high temperatures, the labile end-group can then generate side reactions and thus degradation of the polymer. We report here a novel strategy to remove the nitroxide end-group via a one-pot concept. The strategy relies on the use of compounds such as thiols, radical initiators, carbon tetrabromide and bis(thiobenzoyl) disulfide that all possess very high transfer constants compared to the propagation step in NMP. From a practical point of view, when the desired molar mass and conversion is reached, 1 to 10 equivalents of the transfer agent compared to the nitroxide is added and 5 to 10 min later, when all chain-ends are transformed, the reaction is quenched. The versatility of the procedure was successfully tested with a wide range of monomers and nitroxides. Furthermore, functional group that allows for chain extension of the macroinitiators through another CRP route such as ATRP has been introduced. This novel in-situ method opens the way to new and more versatile copolymer structures.