title: Sequential ROMP of cyclooctenes as a route to linear polyethylene block copolymers.
abstract: AB diblock copolymers were prepared by sequential ring-opening metathesis polymerization of cyclooctenes catalyzed by a Ru-based Grubbs catalyst. The relatively slow polymerization of cis-3-phenylcyclooct-1-ene (3PC) or cis-cyclooct-2-en-1-yl acetate (3AC) was first carried out and then followed by the faster polymerization of unsubstituted cis-cyclooctene (COE) from the active Ru-alkylidene chain ends. In contrast, simultaneous polymerization of the two monomers provides copolymers with a statistical monomer distribution owing to extensive chain transfer. The resulting poly(3PC-b-COE) and poly(3AC-b-COE) diblock copolymers were subjected to hydrogenation to selectively saturate the backbone alkenes. The consequences of architectural variance between the materials from simultaneous vs. sequential polymerizations are reflected by the contrasting thermal characteristics.
authors.affiliation: Department of Chemistry, University of Minnesota, Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Pitet
authors.forename: Jihua
authors.initials: J
authors.lastname: Zhang
authors.forename: Marc A
authors.initials: MA
authors.lastname: Hillmyer
mesh_terms: D002384:Catalysis; D034242:Cyclooctanes / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D020959:Polyethylene / Q000138:chemical synthesis* / Q000737:chemistry; D058105:Polymerization; D012428:Ruthenium / Q000737:chemistry; D013696:Temperature
chemical_list: D034242:Cyclooctanes; D009942:Organometallic Compounds; D012428:Ruthenium; D020959:Polyethylene