Some remarks to the kinetics of anionic polymerization of ethylene oxide in dimethyl sulfoxide

Abstract

The kinetics of ethylene oxide (EO) polymerization in dimethyl sulfoxide with potassium tert-butoxide as initiator at 323, 333, and 343K has been studied. The process follows the first order with respect to initiator in the concentration range 1,5-5,9~10-3mol~dm~3 and the rates are the same as in the polymerization of EO with dimsylpotassium (potassium methylsulfinylmethanide). It is supposed that the tert-butoxide and dimsyl anions are equally effective as initiators and their ionization equilibrium does not affect the polymerization rate. The above conclusion agrees well with the very slow chain transfer to dimethyl sulfoxide in the anionic polymerization of EO.

“Dumb” pH-Independent and Biocompatible Hydrogels Formed by Copolymers of Long-Chain Alkyl Glycidyl Ethers and Ethylene Oxide

“…This can be explained by the addition of the solvent mixture THF/DMSO (5/1), whereas the previously reported structures were polymerized in bulk. Due to the strong solvation effect of cations, such as K + or Ag + by DMSO, an increased propagation rate of the ion pair is achieved, leading to increased reactivity of the active chain end. , The effect of cation solvation by DMSO has been investigated in several epoxide polymerization reactions. − …”

In Situ Kinetics Reveal the Influence of Solvents and Monomer Structure on the Anionic Ring‐Opening Copolymerization of Epoxides

“…Thus, DMSO can be considered as the ideal polar system with a high extent of ion dissociation and free ions as the active species. [ 40 ] On the contrary, THF exhibits a lower dipole moment of 1.63 D and accordingly is a less polar solvent implemented in AROP, permitting only partial dissociation of alkali metal alkoxides. [ 43 ] The reactive species of the alkoxide chain ends in THF can be characterized as ion pairs.…”

“…Therefore, free ions are the primary active species, which mainly contribute to propagation. [ 40 ] The strong solvation effect of DMSO has a documented impact on complexes, for example, it is known to decrease the stability constants of crown ether complexes. [ 46 ] This influence is clearly visible when comparing the reactivity ratios obtained via in situ 1 H NMR measurements in the different solvents.…”

“…EO or substituted epoxides have been investigated with regard to polymerization kinetics in different aprotic polar solvents ranging from linear and cyclic ethers [30][31][32][33] to polar solvents like dimethyl sulfoxide (DMSO) [34][35][36][37][38] and hexamethylphosphoramide (HMPA). [36,39] Depending on the polarity of the solvents, ion pairs were observed as reactive species in ethers, [33,31] whereas free ions were found to be present in the case of the more polar DMSO [40] and HMPA. [39] Nevertheless, although the homopolymerization kinetics in these solvents is well understood, the influence of the solvent on the copolymerization kinetics of EO with monosubstituted epoxides remains largely unexplored.…”