Polymerization in the Presence of Ethers

Remarkably few systematic studies have been made of the kinetics of anionic polymerization in non-polar solvents containing small amounts of ethers in contrast, studies of bulk ether systems abound. Several studies have appeared Yvhich 

In an analogous study, Geerts, Van Beylen and Smets found that the propagation 

It should be mentioned that the viscometric technique yields a weight-average degree of association N, while a number-average (mole fraction) degree of association is actually required for the calculation of equilibrium constants associated with processes such as shown in Eq. (11). However, as is shown in the Appendix the near-monodisperse nature of these polymer systems permits the use of in the calculation of these equilibrium constants. 

The validity of the viscosity measurements regarding the reported influence of anisole and diphenyl ether on the association of the poly(styryl)lithium dimers has, though, been questioned s.ieo.iei) gyffjcg to ote that the fallacies in the data provided have been commented upon elsewhere Even though it is well- 

The opinion has also been expressed that the viscometric technique will overestimate the degree of dissociation in systems where the dissociation constants involving the influence of ethers are studied. This claim can be examined by considering a simple example. Bywater and Worsfold and Meier studied the influence of tetrahydrofuran on the propagation rate of styrene in benzene. Their kinetic results can be interpreted as showing that at an ether/active center ratio of about 10, the poly(styryl)li ium dimers were largely disrupted by solvation with the ether for the process shown in Eq. (11). This joint conclusionis identical to that reached by Morton via the viscometric technique. Thus, at least for the case of poly(styryl)lithium, the viscometric procedure does not appear to overestimate the extent of dimer dissociation. 

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