SYNTHETIC APPLICATIONS OF NONPOLYMERIZABLE MONOMERS IN LIVING CATIONIC POLYMERIZATION - FUNCTIONAL POLYISOBUTYLENES BY END-QUENCHING

The chemistry and kinetics of 1,1-diphenylethylene (DPE) addition to living polyisobutylene was studied at -80 degrees C in methyl chloride/n-hexanes or methylcyclohexane 40/60 v/v. Only monoaddition occurred even when large (9-fold) excess of 1,1-diphenylethylene was used. The kinetics of addition was established by H-1-NMR spectroscopy and by conductivity measurements. The methanol-quenched polymer of the DPE-capped PIB carried exclusively -OCH3 functionality, suggesting that all diphenyl alkyl chain-ends are ionized, which was confirmed by conductivity studies. It was determined that the diphenyl alkyl chain-ends are completely ionized when [TiCl4]/[chain end] greater than or equal to 2 for chain-end concentrations greater than or equal to 10(-3) M. Close to quantitative end-quenching was achieved with 1-methoxy-1-(trimethylsiloxy)-2-methyl-1-propene and 1-cyclohexenyloxy-trimethylsilane.