Cationic polymerization of n-hexyloxyallene by using halogen-bonding organocatalysts

The cationic polymerization of n-hexyloxyallene was investigated by using halogen-bonding organocatalysts (Cat A-Cat D). Although the neutral catalyst Cat C showed a poor polymerization activity, iodine-carrying bidentate cationic catalyst Cat A brought about the smooth polymerization giving rise to a polymer with M-n of 2710 under [Cat A]:[IBVE-HCl]:[monomer] = 10:10:500 in mM concentrations. Judging from the color change of polymerization system and electrospray ionization mass spectra of recovered catalyst, the decomposition of organocatalyst was suggested. When alpha-bromodiphenylmethane was used as an initiator, the relatively controlled polymerization proceeded at the low monomer conversion likely due to the weak halogen-bonding interaction of Cat A with the bromide anion. On the other hand, bromine-carrying bidentate catalyst Cat D gave low-molecular-weight polymers (M-n < 1550) to be less suitable for polymerization. From the H-1-NMR spectrum, it was found that the 1,2-polymerization unit and 2,3-polymerization unit are included in 75:25. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019