Copolymerization of norbornene (NB) and fluorene-containing alkene comonomers using the Me 2 Si(Flu)(N t Bu)-TiMe 2 complex as a catalyst was investigated. The copolymerization successfully proceeded at any monomer feed ratio in high activity and gave copolymers with various comonomer contents. The structure of these copolymers would be gradient because NB was preferentially consumed in a quasi-living polymerization system. Two relaxation processes at 100−150 and 270−300 °C in dynamic mechanical analysis, which show phase-separation of the copolymer, supported the formation of the gradient structure. The obtained copolymers showed a high refractive index as hydrocarbons and extremely low photoelasticity (<10 −11 Pa −1 ). For reducing the photoelasticity, a monomer design free from reactive tertiary carbons would be important.

The copolymerization of norbornene (NB) and various α-olefins [1-octene (O), 1-decene (De), and 1-dodecene (Do)] was achieved with high activity using ( t BuNSiMe2Flu)­TiMe2 (1)-[Ph3C]­[B­(C6F5)4] and 2,6-bis­(1,1-dimethylethyl)-4-methylphenol (BHT)-treated tri-i-butylaluminum ( i Bu3Al) or tri-n-octylaluminum (Oct3Al) as a scavenger. The catalytic systems gave NB/α-olefin copolymers with number-average molecular weights over 100,000 and polydispersity indices below 1.3. The copolymers possessed the gradient structure starting from the NB-rich segment to the α-olefin-rich terminal because of the difference of the monomer reactivity ratios between NB and α-olefins. Films of the copolymers were successfully molded using a melt-pressing procedure. The strain at the break of the copolymer films increased with the length of the alkyl group of the α-olefin accompanied by a decrease in strength. The tensile properties of the copolymers are controlled by the NB content and the M n value. The copolymer films showed transmittance of up to 80% in the visible-light range.

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A series of di- and triblock copolymers composed of gradient norbornene (NB)/higher α-olefin ((1-octene (O) or 1-dodecene (Do)) segments (NB/α-olefin-gradient segments) were synthesized with (t-BuNSiMe2Flu)TiMe2 (1) ‒ [Ph3C][B(C6F5)4] using 2,6-bis(1,1-dimethylethyl)-4-methylphenol...