Computational Evidence for Self-Initiation in Spontaneous High-Temperature Polymerization of Methyl Methacrylate

Title
Computational Evidence for Self-Initiation in Spontaneous High-Temperature Polymerization of Methyl Methacrylate
Author(s)
이명원Soroush, Masoud[Soroush, Masoud]Srinivasan, Sriraj[Srinivasan, Sriraj]Grady, Michael C.[Grady, Michael C.]Rappe, Andrew M.[Rappe, Andrew M.]
Keywords
N-BUTYL ACRYLATE; SPONTANEOUS THERMAL POLYMERIZATION; FREE-RADICAL POLYMERIZATION; MOLECULAR-ENERGIES; UNSATURATED DIMER; AB-INITIO; STYRENE; MECHANISM; PROPAGATION; DENSITY
Issue Date
201102
Publisher
AMER CHEMICAL SOC
Citation
JOURNAL OF PHYSICAL CHEMISTRY A, v.115, no.6, pp.1125 - 1132
Abstract
This paper presents computational evidence for the occurrence of diradical mechanism of self-initiation in thermal polymerization of methyl methacrylate. Two self-initiation mechanisms of interest were explored with first-principles density functional theory calculations. Singlet and triplet potential energy surfaces were constructed. The formation of two Die Is Alder adducts, cis- and trans-dimethyl 1,2-dimethylcyclobutane-1,2-dicarboxylate and dimethyl 2-methyl-5-methylidene-hexanedioate, on the singlet surface was identified. Transition states were calculated using B3LYP/6-31G* and assessed using MP2/6-31G*. The calculated energy barriers and rate constants with different levels of theory were found to show good agreement to corresponding data obtained from laboratory experiments. The presence of a diradical intermediate on the triplet surface was identified. When MCSCF/6-31G* was used, the spin orbit coupling constant for the singlet to triplet crossover was calculated to be 2.5 cm(-1). The mechanism of monoradical generation via a hydrogen abstraction by both triplet and singlet diradicals from a third monomer was identified to be the most likely mechanism of initiation in spontaneous polymerization of methyl methacrylate.
URI
http://hdl.handle.net/YU.REPOSITORY/25662http://dx.doi.org/10.1021/jp107704h
ISSN
1089-5639
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기초교육대학 > 교양학부 > Articles
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