Effect of water on the polymerization of α‐substituted acrylate by anionic initiation

Abstract

It is well known that the results in anionic polymerization of r-substituted acrylates are not the same and that yield, stereoregularity and molecular weight of the polymer strongly depend on the reaction conditions. Even if the reaction conditions are the same, the results are sometimes very different and depend on the research group or time and person even in the same group','). One of the important reasons of disagreement may be the purity of the reagents used. It is extremely difficult to attain the same degree of purity in different groups, at different times o r by different persons. Among various kinds of impurities moisture is the most probable one. In our previous paper it was revealed that the addition of a small amount of water enhanced the isotacticity of the polymer in the polymerization of methyl r-ethylacrylate (MEA) in toluene by butyllithium (~-B u L~)~) .In this work we studied the influence of water on the anionic polymerization of several r-substituted acrylates and found that the presence of a small amount of water generally increased the isotacticity of the polymer owing to the preferential deterioration of syndiotactic site.Polymerization was carried out in a glass ampoule in toluene under dry nitrogen. Toluene containing a known amount of water was mixed with completely dried toluene in various amounts and the mixture was used as a solvent in order to introduce water into the polymerization agents. 'H NMR spectra of the polymers were taken on a 1215

Stereochemistry of Acrylate Polymerization in Toluene Using n-BuLi

“…This is the highest diad isotacticity reported for tBA polymerization. 19 Although the details of the LiOH effect are not immediately known, similar effects have been observed in the polymerization of styrene, 20 • 21 MMA, 6 ethyl methacrylate, 6 • 7 and methyl 2-ethylacrylate. 6 · 8 CONCLUSION Temperature, monomer concentration, and the presence of LiOH affected the stereochemistry of the anionic polymerization of MA and tBA.…”

Stereospecific Polymerization of Methacrylates with Ethylmagnesium Alkoxides

“…The existence of these two active species has been observed in the polymerization of EtMA with BuLi. 9 …”