Tandem ROMP-ATRP

In apparent contradiction with our results, however, no catalyst decomposition was observed over the course of two tandem ROMP-ATRP polymerisations (Scheme 10) mediated by a difunctional ruthenium complex 9 incorporating both a ROMP and an ATRP initiator [27]. Furthermore, halogen exchange has not been reported. In the preparation of these PMMA-PBD diblock copolymers, ROMP and ATRP occurred simultaneously provided that excess PCy3 be added to the reaction mixture. With this in mind, the stability of catalyst 9 over the course of the polymerisations may be related to the observation that additional PCy extends the longevity of the catalyst [25]. 

Scheme 2.3 Synthesis of homopolymer blend particles and graft-copolymer particles by tandem ROMP-ATRP.

H roguez et al. [17] carried out a tandem ROMP of NBE and ATRP of MMA in aqueous heterogeneous systems (Scheme 2.4). In contrast to a mini-emulsion route, this approach avoids the modification step of the initiator 6 to render it water soluble. Despite incomplete monomer conversions (60-80%), well-defined particles with diameters ranging from 20 to 50 nm were prepared. PNBE/PMM A homopolymer blend particles showed a core - shell structure, while... 

Gnanou s group has extensively explored the use of ROMP in emulsion and miniemulsion in addition to dispersion and suspension. The use of ROMP in tandem with ATRP in miniemulsion has proven to be an effective route for making biphasic or Janus particles, consisting of polynorbornene and poly(methyl methacrylate) domains. They were able to use the same ruthenium-based catalyst for both, achieving simultaneous ROMP of norbornene and ATRP of MMA, using miniemulsion polymerization. Stable latexes with minimal... 

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