Living cationic polymerization of isobutylene coinitiated by FeCl3 in the presence of isopropanol

Abstract A simple but effective FeCl 3 ‐based initiating system has been developed to achieve living cationic polymerization of isobutylene (IB) using di(2‐chloro‐2‐propyl) benzene (DCC) or 1‐chlorine‐2,4,4‐trimethylpentane (TMPCl) as initiators in the presence of isopropanol (iPrOH) at −80 °C for the first time. The polymerization with near 100% of initiation efficiency proceeded rapidly and completed quantitatively within 10 min. Polyisobutylenes (PIBs) with designed number‐average molecular weights ( M n ) from 3500 to 21,000 g mol −1 , narrow molecular weight distributions (MWD, M w / M n ≤ 1.2) and near 100% of tert ‐Cl terminal groups could be obtained at appropriate concentrations of iPrOH. Livingness of cationic polymerization of IB was further confirmed by all monomer in technique and incremental monomer addition technique. The kinetic investigation on living cationic polymerization was conducted by real‐time attenuated total reflectance Fourier transform infrared spectroscopy. The apparent constant of rate for propagation ( k p A ) increased with increasing polymerization temperature and the apparent activation energy (Δ E a ) for propagation was determined to be 14.4 kJ mol −1 . Furthermore, the triblock copolymers of PS‐ b ‐PIB‐ b ‐PS with different chain length of polystyrene (PS) segments could be successfully synthesized via living cationic polymerization with DCC/FeCl 3 /iPrOH initiating system by sequential monomer addition of IB and styrene at −80 °C. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012