Synthesis of novel poly(ethylene-ter-1-hexene-ter-dicyclopentadiene)s using bis(β-enaminoketonato)titanium catalysts and their applications in preparing polyolefin-graft-poly(ɛ-polycaprolactone)

Novel terpolymers containing ethylene, 1-hexene and dicyclopentadiene (DCPD) were synthesized using bis(β-enaminoketonato)titanium catalysts [PhNC(R2)CHC(R1)O]2TiCl2 (1a: R1 = Ph, R2 = CF3; 1b: R1 = CF3, R2 = CH3). In the presence of modified methylaluminoxane, these catalysts afforded terpolymers with a broad range of monomer compositions and unimodal molecular weight distributions. 13C NMR spectra reveal the exclusive insertion manner of DCPD maintained under various reaction conditions. DSC results show the melting temperature and the glass transition temperature are very sensitive to the terpolymer composition and the morphology can be easily tuned from semicrystalline state to amorphous state. With ethylene/1-hexene/DCPD molar ratio about 67/28/5, the terpolymer exhibits low glass transition temperature (Tg = −50 °C) and has a great potential to serve as polyolefin elastomer. Additionally, the terpolymer containing 4.3 mol% 1-hexene and 1.6 mol% DCPD was served as the “reactive intermediate polyolefin” for PCL graft reaction. The composition of graft copolymer was well controllable and high graft efficiency was observed. The microscopy studies in conjunction with the tensile tests revealed that PCL graft copolymer is the effective compatibilizer for polyethylene/polar polymer blends by improving the interfacial adhesion between separated phases.