How ionic liquid composition affect Raffinate 1 polymerization in a cationic system?

This research investigates the polymerization of Raffinate 1 under mild conditions using All₃-based initiating systems incorporating five different ionic liquids: [MIM][HSO₄], [Py][HSO₄], [CycIM]Cl, [PVIMCyc]Cl, and [PVIM][HSO₄]. The resulting polybutenes were characterized to determine exo -olefin content, number-average molecular weight (Mₙ), and molecular weight dispersity (Ð). The exo -olefin content of the polymers was below 12 %, with Mₙ values ranging from 6000 to 9500 g·mol −1 and Ð values below 2.03. Compared to the neat AlCl₃/ethanol system, the incorporation of ionic liquids generally led to polybutenes with lower Mₙ, comparable or slightly higher Ð, and similar exo -olefin content. Deconvolution of the GPC curves revealed that all polymers featured three distinct active sites. Among these, the site producing low-molecular-weight polymer chains exhibited the lowest activity, contributing less than 10 wt% to the total polymer population. Additionally, Density functional theory calculations via Natural Bond Orbital analysis showed that the average NBO charge on aluminum in the (AlCl₃)₂ dimer complexes was more positive for ILs than for PILs and S-ILs. These NBO charges revealed a nonuniform distribution between the two aluminum centers upon bonding with the hydroxyl group, with an increase in positive charge on the aluminum center coordinating the hydroxyl. • ILs modulate AlCl₃-catalyzed cationic polymerization of raffinate 1 under mild conditions. • ILs reduce polymer yield, likely due to active site deactivation via IL–AlCl₃ interactions. • GPC deconvolution reveals three distinct active sites, with low-MW sites contributing <10 wt%. • Polymers show low exo -olefin content (<12 %) and dispersity (Ð) below 2.03. • DFT identifies [PVIMCyc] + Cl − as the most stable and effective IL–AlCl₃ adduct.