Oligomers of methyl methacrylate (MMA) were prepared in a flow-tube reactor using metalloesters as initiators in THF at -46 °C. No side products were formed. The rate constants for the formation of the individual t-mers, k^, were calculated by integrating the corresponding differential equations and using optimization procedures to give a best fit to the experimentally determined conversion and molecular weight distribution (MWD). For Li+ as the counterion, is larger than the rate constant for polymerization, kp, where k2, k3, and k4 are smaller than k". This can be explained in terms of interaction of the penultimate ester group in the polymer chain with the counterion ("intramolecular solvation") or in terms of association of ion pairs. For Na+ as the counterion, the dependence of k¡ on i is less pronounced, except for k2 being larger than kp. However, a strong dependence of kp on the concentration of living ends is observed, indicating the coexistence of associated and nonassociated ion pairs. The equilibrium constant for association is estimated.

The interaction of some polar vinyl monomers with lithium picrate (LiPi) in dioxane at 25 °C was studied by a competition technique using cross-linked poly (ethylene oxide) (PEO) as the insoluble ligand. The original competition method was modified for the case where the ionic solute forms more than one type of complex with the soluble and/or the insoluble ligand. The Langmuir-Klotz isotherm of LiPi binding to cross-linked PEO in the presence of monomer gave the apparent binding constant of the polymer gel when in competition with monomer. The formation constants of LiPi complexes with the monomer were then calculated from the apparent binding constant as function of monomer concentration. The nature of the polar group of monomer was found to be of paramount significance. The results were discussed in view of the possibility of complex formation between monomer and active centers in the anionic polymerization of polar vinyl monomers.

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