Methyl Methacrylate as Solvent for the Thermal Decomposition of the Cyclic Molecule Pinacolone Diperoxide: Toward the Polymerization Process

DELGADO RODRÍGUEZ, KARLA; ENRÍQUEZ-MEDRANO, FRANCISCO J.; ADRIANA ESPINOZA MARTÍNEZ; GASTÓN BARRETO; GABRIEL MERINO; GRACIELA MORALES

JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY

JOHN WILEY & SONS INC

Lugar: New York; Año: 2019

0887-624X

The decomposition rate constant (kd) of pinacolonediperoxide (PDP, 3,6-diterbutyl-3,6-dimethyl-1,2,4,5-tetraoxacyclohexane) in methyl methacrylate (MMA) is determined by thekinetic study of its thermal decomposition at temperatures from110 C to 140 C. The calculated kd values for PDP are higher thanthe corresponding values previously determined and reported fordiethyl ketone triperoxide (DEKTP, 3,3,6,6,9,9-hexaethyl-1,2,4,5,7,8-hexaoxacyclononane), for example, at 140 C the kd for PDP is75.4 × 10−5 s−1, while for DEKTP, it is 50.6 × 10−5 s−1. The difference in the kd between 130 C and 140 C indicates that thedecomposition mechanism, sequential and/or concerted, is a function of temperature. The conformations of both initiators justify thehigher kd for PDP in MMA than DEKTP, where one single conformer is found for PDP, whereas 212 conformers are found forDEKTP. Bulk polymerization of MMA using PDP as the initiatorreveals also the presence of an induction period, such as inDEKTP case. This work provides mechanistic insights into theinteractions among the bifunctional cyclic peroxide PDP andthe MMA monomer and their influence on the polymerizationkinetics