Influence of polar modifiers on microstructure of polybutadiene obtained by anionic polymerization. Part 3: Lewis acid alkoxide (μ) and Lewis base amine, amine-ether, and ether mixed-type (σ+μ) polar modifiers

Abstract

ABSTRACTThe influence of mixtures of sodium mentholate (SMT) as a Lewis acid polar modifier and different Lewis base polar modifiers (amines, amine-ethers, ethers) on the microstructure of polybutadiene obtained by anionic polymerization was studied and compared to the influence of the same polar modifiers used separately. Detailed characterization of the polybutadienes in terms of the content and distribution of butadiene isomeric repeating units was performed by 13C NMR and supported by FT-IR-ATR and 1H NMR data analysis. The results obtained indicated that the use of a mixture of Lewis acid and Lewis base in most cases enhanced formation of 1,2 butadiene structures in comparison to the Lewis bases used separately. However, application of a mixture of SMT and DTP resulted in lower vinyl content than when DTP was applied alone. It is worthwhile to note that the combination of a Lewis acid (SMT) and one of Lewis bases tested (DMEAEE) enabled obtaining very high vinyl polybutadiene (88% 1H NMR, 96% 13C NMR).