The spontaneous polymerization of methyl methacrylate-IV

Lingnau, J.; Stickler, Manfred; Meyerhoff, G.

doi:10.1016/0014-3057(80)90050-6

Cited by 47 publications

(38 citation statements)

References 18 publications

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“…Therefore, no stable Diels-Alder adduct and monoradical based from this adduct can be formed. This is in good agreement with results reported in thermal polymerization of MMA 19 and MA. 10 Hydrogen abstraction by the singlet and triplet diradical species from a third monomer and hydrogen abstraction by a third monomer from the singlet and triplet diradical species were studied.…”

Section: Decd and Dbcd Formationsupporting

confidence: 93%

“…The absence of Diels-Alder adducts and the involvement of diradical species in initiation of spontaneous thermal polymerization of MMA, which supports the postulate of Pryor and Lasswell, 18 have been reported. 19 Our recent computational study shows the inability of the Diels-Alder adducts to form monoradical species, and the necessity of a triplet diradical intermediate to generate initiating species for spontaneous thermal polymerization of methyl acrylate. 10 Salem and Rowland 21 and others [22][23][24][25][26][27] have reported the occurrence of diradical crossover from singlet to triplet state, the rules for such crossover, and the possible mechanisms for such intersystem crossing.…”

Section: Introductionmentioning

confidence: 99%

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Self-Initiation Mechanism in Spontaneous Thermal Polymerization of Ethyl and n-Butyl Acrylate: A Theoretical Study

et al. 2010

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In this study, the mechanism of self-initiation in spontaneous thermal polymerization of ethyl and n-butyl acrylate is explored using first-principles calculations. Density functional theory (with B3LYP functional and 6-31G* basis set) was used to study [4 + 2] and [2 + 2] cycloaddition reactions on the singlet and triplet potential energy surfaces. Diels-Alder (DA) dimers of ethyl acrylate [6-ethoxy-2-ethoxycarbonyl-3,4-dihydro-2H-pyran (EDP)] and of n-butyl acrylate [6-butoxy-2-butoxycarbonyl-3,4-dihydro-2H-pyran (BDP)] were found to form on the singlet surface via the concerted pathway proposed by Mayo. The formation of diethyl cyclobutane-1,2-dicarboxylate (DECD) and dibutyl cyclobutane-1,2-dicarboxylate (DBCD) via a nonconcerted pathway was identified on the singlet surface of ethyl and n-butyl acrylate, respectively. The presence of a diradical transition state for the formation of the DECD and DBCD was predicted. Triplet potential energy surfaces for the formation of diradical dimer of ethyl and n-butyl acrylate were computed, and the presence of a triplet diradical intermediate was identified for each of the monomers. A low energy monoradical generation mechanism was identified to be involving hydrogen abstraction by a third acrylate monomer from the triplet diradical species. The molecular structure of the computed monoradical species was found to correlate with chain initiating species of the dominant series of peaks in previously reported electrospray ionization-Fourier transform mass spectra of spontaneously polymerized samples of ethyl and n-butyl acrylate. In view of these observations, it is concluded that this self-initiation mechanism is most likely the initiating mechanism in spontaneous thermal polymerization of alkyl acrylates.

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Section: Decd and Dbcd Formationsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Self-Initiation Mechanism in Spontaneous Thermal Polymerization of Ethyl and n-Butyl Acrylate: A Theoretical Study

et al. 2010

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“…The rate of initiation is not reproducible and the initiation mechanism remains unclear, perhaps related to either dissolved oxygen [98][99][100][101][102][103] or impurities in the system [104]. More recently, it has been shown that acrylates reproducibly undergo self-thermal polymerization at elevated temperatures [55,[105][106][107], a result supported by spectroscopic evidence (ESI/MS) showing the absence of any other chain ends in a polymer produced from the spontaneous BA polymerization experiments [55].…”

Section: Meth(acrylate)mentioning

confidence: 95%

Free‐Radical Acrylic Polymerization Kinetics at Elevated Temperatures

Wang

Hutchinson

2010

Chem Eng & Technol

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Free-radical acrylic homo-and copolymerization kinetics are reviewed, focusing on secondary reactions that impact the polymerization rate and polymer molecular weight (MW) under industrially-relevant synthesis conditions. Dependent on the monomer type (acrylate, methacrylate, styrene), mechanisms that must be considered include chain-end depropagation, monomer self-initiation, formation and reaction of midchain radicals, and incorporation of macromonomers formed by b-scission of midchain radicals. The relative importance of these reactions varies with temperature and, for copolymerization, monomer composition. A comprehensive treatment of these complexities has been completed for polymerizations conducted up to 180°C, but further work is required to extend the applicability of the model to even higher temperatures. IntroductionThe production of low-density polyethylene and associated copolymers at 200-300°C and high pressure is perhaps the bestknown example of high-temperature free-radical polymerization (FRP). However, an increasing number of acrylic resins, produced from a mixture of monomers selected from the methacrylate, acrylate, and styrene families, are also manufactured under higher temperature conditions (>120°C) in homogeneous solution. Low-molecular-weight acrylic resins are the base polymer components for many automotive coatings due to their excellent resistance to chemicals, solvents, ultraviolet light, and abrasion, as well as their exterior durability after crosslinking on the surface of the vehicle [1]. High-temperature conditions are used to produce a variety of other materials for coatings, adhesives, and paints [2]. These conditions are chosen to increase production rates and to decrease (or eliminate) the solvent employed in the formulation while maintaining reasonable solution viscosity [2][3][4].While commercially advantageous, the high polymerization temperatures greatly promote the occurrence of secondary reactions that have a strong impact on polymerization rate and polymer MW, such as monomer self-initiation, chain depropagation, and the formation and subsequent reaction of midchain radicals and unsaturated polymer chains (macromonomers). These reactions occur in addition to the well-known and well-understood set of basic FRP mechanisms consisting of initiation, propagation, termination, and chain transfer [5,6]. This article provides an overview and summarizes recent experimental and modeling efforts by our group and other researchers to improve the understanding of these mechanisms. As most high-temperature acrylic polymerization processes involve multiple monomers, the complexities of including these reactions in copolymerization will also be addressed. An accurate treatment of high-temperature FRP kinetics is a critical component of larger-scale process models used to predict the influence of the operating conditions on reaction rate and polymer properties, guide the selection and optimization of standard operating conditions for existing and new polymer grades, and guide process ...

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“…Methyl methacrylate was also considered to undergo self-initiated polymerization, but more recent work indicates that most, but not all, of the previously reported selfinitiated polymerization was caused by adventitious peroxides that were difficult to exclude by the usual purification techniques [Lehrle and Shortland, 1988]. Other monomers that may be susceptible to self-initiated polymerization are substituted styrenes, acenaphthylene, 2vinylthiophene, and 2-vinylfuran as well as certain pairs of monomers [Brand et al, 1980;Hall, 1983;Lingnau et al, 1980;Sato et al, 1977]. The rate of self-initiated polymerization is much slower than the corresponding polymerization initiated by thermal homolysis of an initiator such as AIBN, but far from negligible; for example, the self-initiated polymerization rate for neat styrene at 60 C is 1:98 Â 10 À6 mol L À1 s À1 [Graham et al, 1979].…”

Section: -4e Pure Thermal Initiationmentioning

confidence: 99%

Radical Chain Polymerization

Odian

2004

Principles of Polymerization

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The spontaneous polymerization of methyl methacrylate-IV

Cited by 47 publications

References 18 publications

Self-Initiation Mechanism in Spontaneous Thermal Polymerization of Ethyl and n-Butyl Acrylate: A Theoretical Study

Self-Initiation Mechanism in Spontaneous Thermal Polymerization of Ethyl and n-Butyl Acrylate: A Theoretical Study

Free‐Radical Acrylic Polymerization Kinetics at Elevated Temperatures

Radical Chain Polymerization

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