Acidic imidazole-based ionic liquids in the presence of diisopropyl ether as catalysts for the synthesis of highly reactive polyisobutylene: Effect of ionic liquid nature, catalyst aging, and sonication. (6th June 2018)

• Record Type: Journal Article
• Authors: Berezianko, Ivan A.; Vasilenko, Irina V.; Kostjuk, Sergei V.
• Is Part Of: Polymer. Volume 145(2018)
• Page Start: 382
• Page End: 390
• Publication Date: 2018-06-06
• Subjects: Cationic polymerization -- Isobutylene -- Highly reactive polyisobutylene -- Ionic liquids; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.04.059
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: A number of imidazole-based acidic (χ(LA)≥0.6) ionic liquids (RmimCl-LA, where R = Et or Bu, LA = AlCl3, AlBr3, i BuAlCl2, FeCl3, GaCl3, and BBr3 ) has been synthesized and their activity in cationic polymerization of isobutylene has been assessed. Among different ionic liquids tested here, emimCl-AlCl3, emimCl-FeCl3 and emimCl-GaCl3 showed the best results in terms of monomer conversion, exo -olefin end group content and polydispersity. It was shown that reaction rate depended strongly on the rate of partial hydrolysis of corresponding ionic liquid and increased in the following order: emimCl-FeCl3 3 3 . It was demonstrated that emimCl-FeCl3 is the most promising catalyst for the synthesis of HR PIB with desired low molecular weight (Mn < 2500 g mol −1 ) and polydispersity (Mw /Mn < 2.5) and high content of exo -olefin end groups (>85%). However, due to poor dispergation of emimCl-FeCl3 in n -hexane as well as its high stability toward hydrolysis, the catalyst aging and/or sonication of reaction mixture is required in order to provide acceptable polymerization rate. Graphical abstract: Image 1 Highlights: Acidic ionic liquids are promising catalysts for the synthesis of highly reactive polyisobutylene. Catalyst aging and/or sonication of reaction mixture leads to significant increase of the reaction rate. EmimCl-FeCl3 affords polyisobutylene with desired low Mn (<2500 g mol −1 ) and polydispersity (Mw /Mn < 2.5). Polyisobutylene with high content of exo -olefin end groups (>85%) was obtained at [IB] = 5.2 M and high temperature (>0 °C).