On the Structure of the Propagating Species in the Anionic Polymerization of Methyl Methacrylate. Kinetic Investigations in Tetrahydrofuran Using Monofunctional Initiators

The effect of TMEDA on the kinetics of the anionic polymerization of methyl methacrylate in tetrahydrofuran using lithium as counterion

“…Thus, many attempts have been made to affect the aggregation equilibria in the polymerization of MMA by using chelating solvents and ligands. Kinetic studies of the polymerization of MMA in the chelating solvent 1,2-dimethoxyethane (DME) of Müller et al [1,[16][17][18] resulted in higher propagation rate constants for Na + and Cs + but lower ones with Li + as counterion. The increase in rate for the larger counterions may be explained by deaggregation of dimers or by an increase of the interionic distance in the ion pairs leading to higher reactivity.…”

Absolute propagation constants in vinyl polymerization

“…With more polar monomers such as methyl methacrylate and other methacrylates, the situation is somewhat different as might be expected. 57 Again, THF is the most often used solvent, but because the active centers are generally less stable at Ϫ20°or higher, lower temperature measurements than those used with styrene are necessary. There is no evidence in this case for the presence of different ion pairs in equilibrium: The Arrhenius plots are linear.…”

Kinetics of the anionic polymerization of methyl methacrylate using cryptated sodium as counterion in tetrahydrofuran

“…The molecular weight distributions are relatively narrow, the values of Hw/mn ranging from 1,05 to 1,2.The dependence of the overall propagation rate constant k, on the concentration of living ends c* and on the total concentration of counterions is given by5):kdi): propagation rate constant of ion-pairs kdo: propagation rate constant of free anions K,,,: dissociation constant of living ends The total concentration of cryptated sodium ions, c (~~+ ,~~~) ,is resulting from the sum of the concentrations stemming from the dissociation of the common ion salt (index: add) and from the dissociation of the living ends (index: pol), respectively: '(Na+ ,222) = C(Na+ ,222)add + C(Na+ ,22z)pl(3) C@a+,m)add = -5. There is a linear dependence of the number-average degree of polymerization on conversion, indicating the absence of transfer reactions.…”