Initiation of complex-radical polymerization of methyl methacrylate in the presence of metallocenes

Abstract

The initiation of radical polymerization of methyl methacrylate in the presence of benzoyl perox ide-metallocene (Cp 2 Fe, Cp 2 ZrCl 2 , and Cp 2 TiCl 2 ; (C 5 Me 5 ) 2 Fe, (C 5 Me 5 ) 2 ZrCl 2 , and (AcC 5 H 4 )(C 5 H 5 )Fe) systems is studied. It is shown that a metallocene affects the rate of initiation and the initial rate of polymer ization. On the basis of quantum chemical calculations, a new mechanism of the initiation reaction may be advanced: Namely, the decomposition of benzoyl peroxide proceeds via the stage of complexation with a metallocene, while the nature of a metallocene determines the probability of complexation and decomposi tion.

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

“…The process of methyl methacrylate bulk polymerization runs in the presence of benzoyl peroxide, and ferrocene is characterized by some interactions between the components of the mixture . In addition to the typical reactions for free radical polymerization (initiation, chain propagation, chain termination, and chain transfer), there are also the following interactions between (1) ferrocene and benzoyl peroxide, (2) ferrocene and monomer, and (3) ferrocene and poly(methyl methacrylate) macroradicals; and the reaction of coordination sites formation and chain propagation on these active sites (reactions 1–9, Scheme ; the structures are indicated in a form suitable for further kinetics modeling). However this scheme did not contain the reactions of adduct Ad ( n, z ) with poly(methyl methacrylate) macroradicals and further transformations of the product formed, that is why these reactions were modeled in this work.…”

“…However this scheme did not contain the reactions of adduct Ad ( n, z ) with poly(methyl methacrylate) macroradicals and further transformations of the product formed, that is why these reactions were modeled in this work. Finally, the scheme from other works was supplemented with following reactions 10–14 (Scheme ).…”

“…The reactions due to the participation of ferrocene in radical‐initiated polymerization of methyl methacrylate (according to the quantum chemical calculations; the reactions 1–9 are literature data from various works, the reactions 10–14 are from this work); n , z , m are chain polymerization degrees…”

“…form effective two‐component (metallocene–benzoyl peroxide), and the three‐component (ferrocene–carbazole derived–benzoyl peroxide, ferrocene–zirconocene or diindenyl zirconocene dichloride–benzoyl peroxide) initiating polymerization systems of methyl methacrylate. An increase in the initiation rate of polymerization in 313–353 K temperature interval and the accelerating effect of metallocenes on the decomposition of benzoyl peroxide at 333 K [Ref. 14] are shown.…”

“…The analysis of the experimental facts, the review of polysites of polymerization systems based on the data of molar mass distribution, and the results of quantum chemical modeling of metallocenes interactions with components of polymerization system have led to the conclusion that in radical‐initiated polymerization along with free radicals, the living active sites of the chain propagation are being formed and do function, and on them a coordinating mechanism of monomer addition to the chain is realized being a ligand of the coordination active site …”