An environmentally benign approach for the synthesis of low molar mass polybutenes from mixed C4 monomers using AlCl3/ionic-liquid initiating systems

In this research, four novel ionic liquid compounds supported on boehmite were synthesized and employed along with AlCl3 to catalyze polymerization of Raffinate 1 (composed of C-4 based mixed monomers) to polybutene, for oils viscosity improver applications. To characterize the supported ionic liquids, FTIR, XRD, TGA, EDS, SEM and Elemental Mapping analyses were employed. Furthermore, (HNMR)-H-1,C-13 NMR and DEPT-135, GC-MS and GPC analyses were performed to assess the effect of designed ionic liquids on the characteristics of obtained polybutenes. Notably, the introduction of the supported ionic liquids led to polybutenes with comparable M-n and D to blank AlCl3 system, but with lower exo-olefins content, which makes the final copolymer more suitable for target application. C-13 NMR and GC-MS analyses confirmed the high participation of isobutylene units in the resulted polybutenes, 75-85%. As an outstanding remark, the suggested AlCl3/ionic liquid initiating system benefits greener polymerization strategy by halving the dosage of hazardous AlCl3 compared to blank system using neat co-initiator.