Nitroxide mediated living/controlled radical polymerisations

Nitroxide-mediated living/controlled radical polymerisations (NMP)... 

Scheme 10.12 Nitroxide (T ) as the living reagent in nitroxide-mediated living/controlled radical polymerisation (NMP).

A corresponding principle applies to controlled radical polymerisation performed in quite a number of modes such as nitroxide-mediated polymerisation (NMP), atom transfer radical polymerisation (ATRP), reversible addition fragmentation chain transfer (RAFT) or catalytic chain transfer (CCT) reactions. All of these variants of controlled radical polymerisation lead to well-defined architectures with the particular advantage that a much larger number of monomers are suitable and the reaction conditions are much less demanding than those of living ionic polymerisation reactions. 

Functionalised PO as block and graft copolymers used as compatibilisers or to increase interactions with other materials are prepared by free radical grafting (the simplest method), metallocene-catalysed copolymerisation of olefins with functional monomers, or anionic polymerisation (silane-containing PO). They are also produced by controlled/living polymerisation techniques such as nitroxide-mediated controlled radical polymerisation, atom transfer radical polymerisation (ATRP), and reversible addition-fragmentation chain transfer (RAFT). 

With SGI as a mediator, the preformed alkoxyamine used in miniemulsion was an oil-soluble low molar mass compound with the 1 -(methoxycarbonyl)eth-1 -yl initiating radical (the so-called MONAMS A5). This type of well-defined initiator allowed good control over the initiation step, the concentration of living chains and the concentration of free nitroxide. Both molar mass and rate of polymerisation were similar to that when the reaction was carried out in bulk (Farcet et al, 2003). The target M could be larger than in the previously presented bicomponent initiating system with persulphate and metabisulphite and the PDIs were systematically lower. 

---