Synthesis of highly reactive polyisobutylene and block copolymers of isobutylene with Isobutyl vinyl ether by FeCl3×iPr2O-Coinitiated cationic (Co) polymerization

In the field of cationic polymerization, ferric chloride (FeCl 3 ) has demonstrated exceptional initiation activity but is plagued by inherent structural instability. Consequently, enhancing the stability of this Lewis acid catalyst while preserving its high reactivity represents a critical research challenge with significant practical implications. This study introduces a novel approach by utilizing the [FeCl 3 ∙i-Pr 2 O] complex as a co-initiator, achieving a one-step protocol for the living cationic polymerization of isobutylene (IB) to produce highly reactive polyisobutylene (HRPIB) with α-olefin content reaching up to 94 %. The research systematically investigates the polymerization kinetics by examining the effects of isopropyl ether (i-Pr 2 O) content, reaction time, solvent polarity, and monomer concentration. Through comprehensive 1 H NMR structural analysis and Gaussian 09 computational simulations, the study reveals that i-Pr 2 O plays a dual-functional role: it not only stabilizes the FeCl 3 active centers but also promotes polyisobutylene chain termination, ultimately yielding three distinct olefin-terminated polyisobutylene derivatives. Building upon this innovative polymerization strategy, the research successfully demonstrates the synthesis of a PIBVE-b-PIB-b-PIBVE triblock copolymer using the [tBuDiCumCl] [FeCl 3 ∙i-Pr 2 O] initiation system.