Polybutadiene modified by epoxidation. 1. Effect of polybutadiene microstructure on the reactivity of double bonds

The reactivity of low-molecular weight sodium polybutadiene (1,2-PB) and n-butyllithium polybutadiene (1,4-PB) has been studied during epoxidation with peracetic acid. The effect of the epoxy groups formed on the polymer solution viscosity has also been investigated. It was found that the rate constant of 1,4-PB epoxidation is ～1.9 times greater than that for 1,2-PB of a similar molecular weight. The reactivity of various structural polymer unit forms was studied by spectroscopic methods (i.r. and ¹H n.m.r.); it was found that reactivity depends on chain microstructure in the following way:for 1,2-PB: trans-1,4 >cis-1,4 ? 1,2for 1,4-PB: cis-1,4 >trans-1,4 ? 1,2An increase in the limiting viscosity number was observed with increasing epoxy content in the 1,2-PB chain, but the opposite effect was observed for 1,4-PB. The solubility parameter, δ, for both kinds of epoxy polybutadiene was found to be similar ($\text{19.8 × 10}{}^3\text{J}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{·}\text{m}{}^{\mathrm{<mtext>?3</mtext><mtext>2</mtext>}}$).