Thermal decomposition of diethyl ketone triperoxide in methyl methacrylate: Theoretical and experimental study of the initial solvation state and its influence on the polymerization process

Abstract

The decomposition rate constant (kd) of diethyl ketone triperoxide (DEKTP, 3,3,6,6,9,9‐hexaethyl‐1,2,4,5,7,8‐hexaoxacyclononane) in methyl methacrylate (MMA) was determined by the kinetic study of its thermal decomposition at temperatures from 110 to 140°C. The calculated kd for DEKTP in MMA was 2.4 times lower (at 130°C) compared with that previously determined and reported in styrene (St). Density functional theory (DFT) calculations demonstrated that the decomposition of DEKTP molecule in MMA required higher interaction energy than in St, thus explaining its lower kd value. Bulk polymerization kinetics of MMA using DEKTP as the initiator revealed the presence of an induction period, in contrast with St polymerization, providing clear evidence of the solvation state influence at early polymerization stages. This work provides mechanistic insights into the interactions among the multi‐functional cyclic peroxide DEKTP and vinyl monomers; St and MMA, and their influence on the polymerization kinetics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42905.

Solution Polymerization of Methyl Methacrylate in an Ionic Liquid Employing Cyclic Multifunctional Initiators

“…On the other hand, the polydispersity values in the case of the polymerizations in the presence of IL are higher (ranging from 4 to 7) probably due to the presence of different species associated to the change in the initiation mechanism. The behavior observed herein for the evolution of molecular weights is opposite to the previously reported in bulk conditions for MMA polymerizations employing these multifunctional initiators, where the DEKTP behaves as a multifunctional initiator, with an increase in molecular weight as the reaction takes place, from 110 to 130°C while PDP decomposes in a sequential manner in the temperature range of 110 to 120°C …”

“…As it was previously reported, the thermal decomposition of this kind of multifunctional initiators is strongly dependent of the solvent used . Moreover, when monomers such as MMA and styrene were employed as the reaction media, there was clear evidence of a strong dependence of the monomer nature on the initiators decomposition. In this sense, and taking the pinacolone diperoxide (PDP) at 140°C as an example, its decomposition rate constants ( k d ) was 27.4 × 10 −5 s −1 in benzene, 43.4 × 10 −5 s −1 in acetic acid, 30.5 × 10 −5 s −1 in acetonitrile, 23.2 × 10 −5 s −1 in n ‐octane, 75.8 × 10 −5 s −1 in 2‐methoxymethanol and 29.6 × 10 −5 s −1 in toluene .…”

Methyl methacrylate as solvent for the thermal decomposition of the cyclic molecule pinacolone diperoxide: Toward the polymerization process

“…reported the thermal decomposition of DEKTP at 130 °C in MMA‐ethylbenzene mixtures (0.1–1.0 mol L −1 ), and MMA polymerizations in these systems, finding high polymerization rates and elevated molecular weights . Furthermore, our group described such decomposition but carried out entirely in MMA in the temperature range of 110–140 °C, and lower k d values were obtained in comparison with those reported for styrene under similar experimental conditions . The MMA polymerization reaction initiated with DEKTP presented an induction period, which was not observed in the case of styrene.…”

“…Thermal decompositions of bifunctional and trifunctional cyclic peroxides, such as pinacolone diperoxide (PDP, 3,6‐diterbutyl‐3,6‐dimethyl‐1,2,4,5‐tetraoxacyclohexane) and diethyl ketone triperoxide (DEKTP, 3,3,6,6,9,9‐hexaethyl‐1,2,4,5,7,8‐hexaoxacyclononane), have been evaluated and reported in different solvents or a mixture thereof, such as acetone–toluene, acetone‐ n ‐propanol, diethylamine, toluene, chlorobenzene, acetonitrile and ethanol, and so on. However, there is a limited number of reports related to thermal decompositions and kinetic behaviors of these cyclic peroxides in the presence of vinyl monomers as solvents . In this sense, Cañizo et al .…”

“…The MMA polymerization reaction initiated with DEKTP presented an induction period, which was not observed in the case of styrene. This last situation is a clear evidence of the influence of initial solvation status in early stages of MMA polymerizations initiated by DEKTP …”