High transparent alternate copolymer of norbornene with isoprene catalyzed by bis(phenoxy–imine) titanium complex

Abstract

A novel highly transparent alternate copolymer of norbornene with isoprene was prepared using a coordination catalytic system composed of bis(phenoxy–imine) titanium complexes and triisobutylaluminum. Distortionless enhancement by polarization transfer ¹³C NMR microstructure analysis of the copolymer reveals the vinyl-type addition nature of norbornene in the copolymer. The content of norbornene in the copolymer stayed constant at approximately 53%, varying the monomer feed ratio and conversion, which implied an alternating nature in the copolymer backbone. The copolymer obtained with a relatively high molecular weight (M_n = 1.05 to 2.27 × 10⁵ g mol⁻¹) shows good thermal stability and a moderate glass transition temperature (T_g = 75–79.5 °C). The copolymer also exhibits admirable transparency in the visible wavelengths (maximal transmittance ≈ 98%).