Modeling of elementary reactions and kinetics of radical‐initiated methyl methacrylate polymerization in the presence of ferrocene

Abstract

On the basis of quantum chemical modeling, a kinetic scheme of methyl methacrylate polymerization initiated by benzoyl peroxide in the presence of ferrocene was proposed. The process runs by mechanism, which includes the reactions of free radical polymerization, and the reactions leading to formation and operability of two type coordination active sites that are capable of converting into each other. On the basis of the proposed scheme, a kinetic model was developed. This model quantitatively described the following: the experimentally determined time dependences of the methyl methacrylate conversion, the conversion dependencies of the numberaverage and weight-average molar masses of poly(methyl methacrylate), the stereoregularity values of poly(methyl methacrylate), and the time dependencies of the methyl methacrylate conversion upon its polymerization on poly(methyl methacrylate) macroinitiators obtained in radical-initiated polymerization in the presence of ferrocene. As a result of solving the inverse kinetic problem, the parameters of temperature dependences of the reaction rate coefficients of the proposed kinetic scheme were found. K E Y W O R D Skinetic model, quantum chemical modeling, radical-initiated methyl methacrylate polymerization in the presence of ferrocene 742

Kinetics of Methyl Methacrylate Polymerization in the Presence of Initiating Systems “Peroxide + Zirconocene Dichloride” When the Methyl Methacrylate Adhesive is Cured

“…It has been experimentally established that the increase of the ferrocene concentration in the radical coordination polymerization of methyl methacrylate contributes to the smoothing of the gel effect. 41 The time dependencies of the methyl methacrylate conversion polymerized on the coordination active sites for this process have a linear form, 41 5, 7, and S5−S8, all (e)] basically corresponds to the form of similar conversion dependencies of the poly(methyl methacrylate) molecular weights obtained as a result of classical radical polymerization.…”

“…It is typical that it would not be observed during the radical coordination polymerization of methyl methacrylate in the presence of initiating system "benzoyl peroxide + ferrocene", when the slope of the time dependence of conversions U ci would not increase during the process. 41 Thus, it can be concluded that the radical coordination polymerization of methyl methacrylate in the presence of ferrocene and in the presence of zirconocene dichloride has a qualitative difference. In the first case, polymerization is characterized by the parallel functioning of radical and coordination channels for the formation of poly(methyl methacrylate) chains.…”

“…41 The time dependencies of the methyl methacrylate conversion polymerized on the coordination active sites for this process have the linear form. 41 At the same time, no smoothing of the gel effect for the time dependencies of the methyl methacrylate conversion in the presence of zirconocene dichloride was experimentally found [Figures 2, 4, and Figure 3, (a)]. 2.…”

“…The kinetic model was made in accordance with the algorithm from ref . The equations of the kinetic model were written using the method of generating functions with respect to the moments of the molecular weight distribution of the high molecular weight components of the reaction system μ u v = ∑ n = 1 ∞ n y [ X u false( n false) ] , goodbreak0em2em⁣ μ u v w = ∑ n = 1 ∞ ∑ z = 1 ∞ n v z w false[ X u ( n , z ) false] where μ is a statistical moment of the molecular weight distribution of the high molecular weight component of the reaction system X ; u is the ordinal number of the high molecular weight component of the reaction system; v and w are the order of the statistical moment; and n and z are the lengths of polymer chains ( n and z are used simultaneously when two separately coordinated polymer chains to the zirconium atom are present in the composition of the high molecular weight component).…”

“…Based on experimental and theoretical studies of classical radical polymerization, − on experimental studies − of the kinetics of radically initiated polymerization processes in the presence of metallocenes and molecular characteristics of the resulting polymers, as well as studies devoted to theoretical quantum chemical ,− and kinetic − modeling of these processes, it was concluded that two channels of polymer chain formation exist concurrently in the polymerization under consideration, the radical and the coordination channels; therefore, it can be called radical coordination polymerization. During the polymerization of methyl methacrylate in the presence of benzoyl peroxide and ferrocene (compared to the polymerization of methyl methacrylate in the presence of benzoyl peroxide only) the following was found: (1) the molecular weight of the resulting poly­(methyl methacrylate) decreases, and at the same time, the average molecular weights of the polymer increases with growing conversion of methyl methacrylate − (which is observed in processes with reversible chain deactivation); (2) the proportion of syndiotactic triads in the composition of poly­(methyl methacrylate) increases (which indicates to the course of chain coordination propagation reactions); (3) poly­(methyl methacrylate) is obtained, which is capable to act as a macroinitiator with constant activity while adding new portions of a monomer .…”