Highly soluble polynorbornene prepared by an anilinonaphthoquinone-ligated nickel complex via coordination-insertion polymerization

•An anilinonaphtoquinone-ligated nickel complex activated by B(C6F5)3 conducts coordination-insertion polymerization of norbornene with high activity to give high molecular-weight polymers.•Vinyl-addition-type polynorbornene is dissolved in cyclohexane at room temperature.•The self-standing film of the polynorbornene prepared by solution casting possesses good transparency in the UV-visible region.

Norbornene polymerization was conducted with 2-(2,6-diisopropylanilino)-1,4-naphthoquinone-ligated nickel complex (1) activated by B(C6F5)3 and dried modified methylaluminoxane (dMMAO) in toluene at 40 °C. The 1-B(C6F5)3 system showed higher activity than the 1-dMMAO system and gave higher molecular-weight polynorbornene via coordination-insertion polymerization. The solubility of the polymer obtained by 1-B(C6F5)3 was also higher than that obtained by 1-dMMAO, and dissolved in cyclohexane even at room temperature. The self-standing films of the polynorbornene obtained by the B(C6F5)3 system were prepared by the solution casting method with cyclohexane. The films thus prepared showed good transparency in the UV–visible region. The 13C NMR spectra of the polymers indicated that the microstructures of the polynorbornenes were dependent on the activator used. The heat decomposition temperature, i.e., 10% weight loss, determined by TGA was 386 °C for the polymer obtained by 1-B(C6F5)3 and 402 °C for that obtained by 1-dMMAO, respectively.

Graphical abstractHighly soluble vinyl-addition-type polynorbornene was 2-(2,6-diisopropyllanilino)-1,4-naphthoquinone-ligated nickel complex activated by B(C6F5)3. Self-standing transparent films were prepared from cyclohexane solution at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slide