Synthesis of Well-Defined Graft Copolymers via Coupled Living Anionic and Living Ring Opening Metathesis Polymerisation

Abstract

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-dicarboxyl chloride and living ROMP of the macromonomer using well-defined Schrock molybdenum initiator to produce well-characterised graft copolymer is described. The ROMP of the macromonomers of different molecular weights revealed the presence of a limit on the length of polynorbornene backbone chain and on the length of 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. It appears that as the length of polystyrene block in the macromonomer is increased the metathesis reaction becomes sterically inhibited and eventually stops. The cessation of polymerisation is found to be dependant primarily on macromonomer molecular weight rather than reaction duration. Furthermore the ROMP of the macromonomers is found to be living.