Synthesis of polyisobutylene with arylamino terminal group by combination of cationic polymerization with alkylation

Abstract

The controlled cationic polymerization of isobutylene (IB) initiated by H2O as initiator and TiCl4 as coinitiator was carried out in n-Hexane/CH2Cl2 (60/40, v/v) mixture at −40 °C in the presence of N,N-dimethylacetamide (DMA). Polyisobutylene (PIB) with nearly theoretical molecular weight (Mn = 1.0 × 104 g/mol), polydispersity (Mw/Mn) of 1.5 and high content (87.3%) of reactive end groups (tert-Chlorine and α-double bond) was obtained. The Friedel-Crafts alkylation of triphenylamine (TPA) with the above reactive PIB was further conducted at different reactions, such as [TPA]/[PIB], solvent polarity, alkylation temperature, and time. The resultant PIBs with arylamino terminal group were characterized by 1H NMR, UV, and GPC with RI/UV dual detectors. The experimental results indicate that alkylation efficiency (Aeff) increased with increases in [TPA]/[PIB], reaction temperature, and reaction time and with a decrease in solvent polarity. The alkylation efficiency could reach 81.0% at 60/40(v/v) mixture of n-Hex/CH2Cl2 with [TPA]/[PIB] of 4.49 at 50 °C for 54 h. Interestingly, the synthesis of PIB with arylamino terminal group could also be achieved in one pot by combination of the cationic polymerization of IB initiated by H2O/TiCl4/DMA system with the successive alkylation by further introduction of TPA. Mono-, di- or tri-alkylation occurred experimentally with different molar ratio of [TPA]/[PIB]. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 936–946, 2008