Polymers with novel topologies by ring-opening metathesis polymerization of macromonomers

This paper reviews the possibilities of engineering novel macromolecular topologies via "living" ring-opening metathesis polymerization (ROMP) of miscellaneous macromonomers. It is shown that multibranched polystyrene poly(ethylene oxide) and polybutadiene polymacromonomers of varying compactness and branch number can be prepared by ROMP of corresponding macromonomers, provided the macromonomers carry an end-standing norbornene unsaturation. Janus-type architectures are also accessible by this technique: such entirely novel topologies can be obtained by sequential ROMP of two different macromonomers whereas their statistical copolymerization affords heteroarmed macromolecules. Advantage has also been taken of the versatility of this technique to prepare compact polymeric architectures that behave like unimicellar systems: structures whose inner part and outer layer are chemically different can be derived through home/polymerization of macromonomers that are themselves block copolymers.