Well-defined graft copolymers via coupled living anionic and living ring opening metathesis polymerisation

The synthesis of macromonomers via the reaction of living polystyrene capped with propylene oxide with bicyclo[2.2.1]hept-5-ene-2,3-trans-dicarbonyl chloride and living ROMP of the macromonomers using well-defined Schrock molybdenum initiator to produce well-characterised graft copolymers is described. The scaling up of the ROMP of the macromonomers of different molecular weights revealed the presence of an experimental limit to the length of polynorbornene backbone chain and to the length of the polystyrene graft. It is found that as the length of polystyrene graft in the macromonomer is increased the length of polynorbornene backbone chain in the graft copolymer is decreased an observation ascribed due to steric hindrance. The ROMP of macromonomers of different molecular weight has been shown to be living allowing the synthesis of tapered and block copolymers.