Real-time Fourier Transformation Infrared (FTIR) spectroscopy with a fiber optic transmission probe (TR) was used to monitor the polymerization of isobutylene (IB) initiated by alpha-methylstyrene epoxide (MSE) and 1,2-epoxi-2,4,4-trimethylpentane (TMPO-1) in conjunction with TiCl4 and BCl3. In the presence of an equimolar amount of BCl3, MSE and TMPO-1 underwent ring opening via S(N)1 mechanism. In contrast to TiCl4-coinitiated reactions, no oligoether formation via S(N)2 mechanism was observed. TMPO-1 with excess BCl3 initiated IB polymerization, yielding a telechelic PIB carrying alpha-primary OH and omega-tertiary Cl functionalities with 70% initiator efficiency. (C) 2008 Wiley Periodicals, Inc.