High crystallinity polyethylene obtained in biphasic polymerization using pyridinium chloroaluminate ionic liquid

Abstract

A series of N-n-alkylpyridinium chloroaluminate ionic liquids [Cn-py][AlCl4] (where n-alkyl = n-butyl, n-hexyl, and n-octyl) was applied as a medium of the Cp2TiCl2 catalyst, activated by AlEtCl2 or AlEt2Cl, to evaluate the influence of the studied ionic liquids on the performance of the biphasic ionic liquid/hexane ethylene polymerization and the properties of the produced polyethylene (PE). The best results were obtained using N-n-butylpyridinium chloroaluminate. The polyethylene obtained in the biphasic polymerization have the high crystallinity, which was confirmed by DSC, WAXS and PALS methods, as well as the bulk density comparable to commercial HDPE. These unique properties results from the biphasic mode of the ethylene polymerization where the ionic liquid is used to immobilize the catalyst, and polyethylene is produced in the ionic liquids phase.