Cationic polymerization of isobutylene using AlCl_3OBu _2 as a coinitiator: Synthesis of highly reactive polyisobutylene

摘要

The application of the 2-phenyl-2-propanol (CumOH)/AlCl_3OBu _2 initiating system to the synthesis of highly reactive polyisobutylene containing 86-95% of exo-olefin end groups. Isobutylene was dried in the gaseous state by passing through the column packed with CaCl _2. Ethyl acetate and pyridine were distilled twice from CaH _2 under an inert atmosphere. Diphenyl ether was distilled from CaH2 under reduced pressure. Size exclusion chromatography (SEC) was performed on a PL-GPC 50 integrated GPC system with two columns and one precolumn thermostated at 30°C. The detection was achieved by differential refractometer. Tetrahydrofuran (THF) was eluted at a flow rate of 1.0 mL/min. diphenylthiocarbazone as an indicator. The polymerization reactions were carried out in glass tubes under an argon atmosphere at different temperatures. It is evident that the molecular weight of polymers synthesized with the CumOH/AlCl_3OBu_2 initiating system is controlled by the concentration of free base (Bu2O), not by [isobutylene]/[CumOH] ratio.