The living cationic polymerization of α-methylstyrene with BCl3 as coinitiator

The cationic polymerization of alpha-methylstyrene (alpha MeSt) was studied using the cumyl chloride (CumCl), (CH3)(3)C-CH2-C(CH3)(2)-CH2-C(Ph)(2)-OCH3 (TMPDPEOMe) or (CH3)(2)C(Ph) CH2C(CH3)(Ph)Cl (the HCl adduct of alpha MeSt dimer, Di alpha MeStHCl)/BCl3 initiator/coinitiator systems in the presence of proton trap in methyl chloride:hexanes (MeCl:Hex) or MeCl:methylcyclohexane (MeChx) mixtures at -80 and -60 degrees C. While CumCl is not an efficient initiator in conjunction with BCl3, TMPDPEOMe and Di alpha MeStHCl were found to be very efficient initiators. The polymerization was much faster in the MeCl:Hex mixture than in MeCl:MeChx. The polymerization rate was also higher at -80 degrees C than at -60 degrees C in the same solvent. The polymerization was found to be living at -80 degrees C, as well as at -60 degrees C, giving rise to poly(alpha-methylstyrene)(P alpha MeSt) with controlled molecular weight and narrow molecular weight distribution (M-w/M-n similar to 1.1-1.2). The chain ends remained living for up to 40 minutes under monomer starved conditions at -80 degrees C, but they rapidly decomposed at -60 degrees C.