Haloboration-initiation in macromolecular engineering.

摘要

The scope, limitations, and possible applications of direct initiation with boron trihalides in macromolecular engineering were investigated, to obtain end functional polymers.; The polymerization of α-methyl styrene was studied in the absence of a separately added cationogen and in the presence of a proton trap, using boron halides. The effect of monomer and BX₃ concentration, solvent polarity, and temperature were examined. Kinetic experiments support that initiation is by haloboration, but direct proof was only obtained for BI3. For polymers prepared with BI₃, the presence of one boron per chain was confirmed by elemental analysis, while the high M_n's obtained with BCl₃ and BBr₃ prevented quantitative analysis of head and end groups.; The technique of direct initiation with boron trilialides was used to synthesize telechelic polyisobutylenes (PIBs) by converting the boron-containing head group directly obtained by haloboration-initiation into various functional groups. This head group functionalization based on organoboron chemistry was combined with end group functionalization techniques developed for PIB earlier to obtain asymmetric telechelic PIBs.