Lv. Shcheglova et al., KINETICS OF ISOPRENE POLYMERIZATION IN THE PRESENCE OF 2-ETHYLHEXYLSODIUM AND ITS MIXTURES WITH 2-ETHYLHEXYLLITHIUM IN HYDROCARBON SOLVENTS, Macromolecular chemistry and physics, 199(6), 1998, pp. 1025-1028
The anionic polymerization of isoprene with 2-ethylhexylsodium soluble
in hydrocarbons in the absence of electron donor additives has been s
tudied. The kinetics of the propagation reaction is shown to strongly
depend on the solvent used. In toluene, the reaction order in initiato
r appears to be fractional, its value being dependent on the initiator
concentration, while in heptane the first order is known to be follow
ed. For polymerization in toluene, a scheme is suggested where monomer
ic and tetrameric active species are supposed to take part in propagat
ion. With a non-linear regression fit, apparent constants in the equat
ion describing this scheme were evaluated. The kinetics of isoprene po
lymerization with the mixed 2-ethylhexylsodium/2-ethylhexyllithium ini
tiator, as well as W spectra of the living polymers obtained, were als
o studied. Formation of complex active species is suggested.