Decay of the ESR signal in ultraviolet‐irradiated poly(methyl methacrylate)

Michel, Rainer; Chapman, F. W.; Mao, Ting

doi:10.1002/pol.1967.150050325

Cited by 20 publications

(8 citation statements)

References 12 publications

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“…For instance, Atherton et al,6 Best and Kasai,7 Ranby and Rabek,8 Iwasaki and Sakai,9 and Doetschman et al10 have postulated different rotational configurations of the polymer end group of radical I. Other researchers believe that the nine‐line spectrum is due to more than one species of radicals such as Michel et al11 and Billaud et al12 who invoke two different radical species. This point of view is supported by different decay rates of the two peak families 11.…”

Section: Resultsmentioning

confidence: 99%

“…Other researchers believe that the nine‐line spectrum is due to more than one species of radicals such as Michel et al11 and Billaud et al12 who invoke two different radical species. This point of view is supported by different decay rates of the two peak families 11. Another explanation could be that a nine‐line spectrum is superimposed on an additional spectrum, which decays at a different rate, but definite identification of two such radical species has not been reported.…”

Section: Resultsmentioning

confidence: 99%

“…Its signal is thus expected to be lower than the signal intensity of the very stable radical III. Michel et al11 already mentioned that possibly the nine‐line spectrum is superimposed on an additional spectrum of higher stability. From the above reported data and literature, it is proposed that the experimental spectrum can be explained by the superposition of EPR signals arising from “propagating” radical I composed of nine weak peaks from which five peaks overlap five strong peaks arising from allylic radical III (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Generally, the appearance of a “free radical” spectrum observed in the case of free‐radical methacrylate polymerizations is attributed to the propagating radical. The exact assignment of a radical structure and conformation has been the subject of many investigations,6–12 but there is still no consensus on the conformation of the free radicals, and some disagreements persist even on the radical chemical structures.…”

Section: Introductionmentioning

confidence: 99%

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Identification of free radicals trapped in solid methacrylated resins

Truffier-Boutry

Gallez

Demoustier‐Champagne

et al. 2003

J. Polym. Sci. A Polym. Chem.

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Photopolymerization of methacrylated dental resins at room temperature leads to the appearance of long-life free radicals because of system vitrification. These free radicals were observed by electronic paramagnetic resonance (EPR), and their characterization was undertaken by reference to the reactional mechanism, from the comparison with the model EPR signal and from theoretical simulation. Overlapping of two EPR signals assigned to two different kinds of radicals because of methacrylate end groups accounted for all the experimental and theoretical results.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Identification of free radicals trapped in solid methacrylated resins

Truffier-Boutry

Gallez

Demoustier‐Champagne

et al. 2003

J. Polym. Sci. A Polym. Chem.

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“…[2]. Equation [3] was found to fit the data satisfactorily over the entire temporal range that was monitored, as shown by the residuals in Fig. 2.…”

Section: Calculation and Reproducibility Of Rate Constants--inmentioning

confidence: 73%

Effects of Stereoregularity on the Photodegradation of Poly (methyl Methacrylate) Exposed to Ultraviolet Irradiation

Franke

1991

J. Electrochem. Soc.

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was the winner of the Joseph W. Richards Fellowship. The Summer Fellowship Awards are made "without regard to sex, citizenship, race, or financial need, to a fellow or teaching assistant pursuing work between the degree of B.S. and Ph.D. on a subject in a field of interest to The Electrochemical Society." They are intended to cover a period during which the recipient has no financial support for the continuance of his or her work. The Edward G. Weston Summer Fellowship Report James E. Franke was born in Dover, New Jersey, in 1964, but he has been a resident of West Virginia for the last 15 years. In 1985 he completed his B.S. (chemistry and mathematics majors) and A.S. (engineering) degrees at Shepherd College in Shepherdstown, West Virginia. Mr. Franke also holds a M.S. degree in chemistry from Rensselaer Polytechnic Institute in Troy, New York, where he is presently a Ph.D. candidate in physical chemistry under the direction of Dr. Joseph T. Warden. At the present time, his research interests center on the application of time-resolved electron spin resonance spectroscopy to the study of photochemically induced free radical reactions.

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ESR spectra of poly(methacrylic acid) and poly(methyl methacrylate): Reinterpretation of the 9‐line spectrum

Iwasaki

Sakai

1969

J. Polym. Sci. A‐1 Polym. Chem.

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The temperature dependence of the ESR spectra of poly(methacrylic acid) and poly‐(methyl methacrylate) γ‐irradiated at room temperature was studied between −196°C and +25°C. The conventional 9‐line spectrum was observed throughout this range with no significant spectral change, in contrast to the propagating radical ··· CH2°C(CH3)COOR found in methacrylic acid monomer or barium methacrylate dihydrate irradiated at −196°C. In addition, the irradiation of methacrylic acid monomer with a low dose at 0°C gave the same 13‐line spectrum as that of the propagating radical obtained by the irradiation at −196°C, while prolonged irradiation at 0°C gave the same conventional 9‐line spectrum as that of poly(methacrylic acid) or poly(methyl methacrylate). The conventional 9‐line spectrum has a much weaker 4‐line component than that of the propagating radical. The difference comes from the surrounding matrix, and the conventional 9‐line spectrum is well interpreted by introducing the concept of the distribution of the conformational angle in the irregular polymer matrix. From simulation of the ESR spectrum, it was found that the intensity of the 4‐line component is very sensitive to the distribution, and that the observed 9‐line spectrum is well reproduced assuming a Gaussian distribution (half‐height width of 5–6°) around the most probable conformation which is nearly the same as that of the propagating radical, where the conformational angles of the two CHβ bonds to the half‐filled p‐orbital are 55° and 65°.

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Decay of the ESR signal in ultraviolet‐irradiated poly(methyl methacrylate)

Cited by 20 publications

References 12 publications

Identification of free radicals trapped in solid methacrylated resins

Identification of free radicals trapped in solid methacrylated resins

Effects of Stereoregularity on the Photodegradation of Poly (methyl Methacrylate) Exposed to Ultraviolet Irradiation

ESR spectra of poly(methacrylic acid) and poly(methyl methacrylate): Reinterpretation of the 9‐line spectrum

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