Low temperature reactions of polymeric free radicals. Addition to double bonds

Dubinskaya, A.M.; Butyagin, P. Yu.

doi:10.1016/0032-3950(68)90037-3

Cited by 10 publications

(4 citation statements)

References 10 publications

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“…The lifetime of radicals generally decreases with increasing temperature. An activation energy for a low temperature proton transfer reaction has been reported of only 4-5 kcal/mole for poly(methyl methacrylate) and for polyethylene [100,110,111].…”

Section: How Bonds Rupturementioning

confidence: 99%

“…Discussions of reaction kinetics frequently involve the cage concept [142,143]. To study the primary process, other reactions can be reduced by performing experiments at low temperatures and by using frozen polymer solutions, where the macromolecules are isolated [112][113][114][144][145][146][147]. Chemiluminescence has been used to determine the extent of mechanochemistry [117][118][119][120][121].…”

Section: How Bonds Rupturementioning

confidence: 99%

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Mechanisms

Casale

1978

Polymer Stress Reactions

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Section: How Bonds Rupturementioning

confidence: 99%

Section: How Bonds Rupturementioning

confidence: 99%

Mechanisms

Casale

1978

Polymer Stress Reactions

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“…Ball-mill grinding (BMG) is a popular technique used for polymer synthesis, − polymer degradation, − and other mechanochemical transformations. − Early studies pertaining to the BMG of PMMA were interested in the macroradicals that were generated upon chain scission. − Chain scission necessitates a reduction in the molecular weight, which will continue to decrease until reaching a limiting value (often referred to as the limiting molecular weight, M lim ). The M lim for PMMA is dependent on the grinding conditions, but has been reported to be as low as 5 or 6 kDa. ,, Thus, ball-milling of PMMA typically yields moderate to low molecular weight PMMA without depolymerization (Figure B).…”

Section: Introductionmentioning

confidence: 99%

Depolymerization of Polymethacrylates with Ball-Mill Grinding

Jung,

Cho,

Peterson

et al. 2024

Macromolecules

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In this report, we demonstrate that polymethacrylates can undergo appreciable depolymerization, with mild conditions and without reactive end groups, using ball-mill grinding (BMG). For instance, the important commercial polymer, poly(methyl methacrylate) (PMMA) underwent up to 41% depolymerization to monomer within 8 min of grinding. We explored the factors that influence the depolymerization conversion and found temperature (heating to only 43 °C), addition of a small amount of liquid (μL of tert-butyl alcohol), and ball number/size to be the most important parameters. We also applied this method to other polymethacrylates and found the pendent substituent to influence the extent of depolymerization. Addition of a liquid was found to reverse the effects of the substituent that were observed with bulk grinding. For instance, among the polymethacrylates studied, PMMA had the lowest depolymerization conversion in bulk and one of the highest depolymerization conversions in a slurry. Notably, the molecular weight of the residual polymer is remarkably low, ca. 1 kDa, demonstrating the excellent degradation performance of BMG. Overall, this work provides important mechanistic insight into depolymerization reactions under ball-milling conditions and represents an important step in expanding BMG as a tool for the chemical recycling of polymethacrylates.

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“…6 There are large number of studies of mechanical fracture of poly(methyl methacrylate) (PMMA) and other polymers. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Many of these report the observation of a nine-line ESR spectrum for PMMA fractured at 77 K in vacuum. 8,10,11,13 It has also been demonstrated by several researchers that PMMA had a nine-line ESR spectrum when it was radiated by g, X, and UV-irradiation.…”

Section: Introductionmentioning

confidence: 99%

An electron spin resonance study of mechanical fracture of poly(methyl methacrylate)

Kaptan

Tatar

1997

J. Appl. Polym. Sci.

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In this article, initially, we designed a simple drilling apparatus to obtain the mechanoradicals of poly(methyl methacrylate) (PMMA). Using this apparatus, we prepared some PMMA samples at 77 K in vacuum. We observed some electron spin resonance (ESR) signal of these samples. It is found that the ESR spectrum of mechanically fractured PMMA strongly depends on the vacuum conditions. The spectrum observed from the mechanically fractured PMMA in 10 04 torr vacuum at 77 K coincides with the characteristic spectrum of the ''nine-line'' ESR spectrum of PMMA. Otherwise, because of the interaction between the polymer powders and air during the stage of preparing the sample, some of the mechanoradicals convert into the peroxy radicals. In this situation, spectrum is mainly nine-line and partially superposed with the spectrum of peroxy radicals. The peroxy line observed at low temperatures disappears rapidly from the mechanoradicals with increasing temperature. It vanishes completely at Ç 300 K and the spectrum turns into the nine-line spectrum of PMMA. Changes in the nine-line spectrum of mechanoradicals were investigated in the 100-350 K temperature interval. The line intensities were measured at each temperature. It was shown that the line intensities of both A and B do not change with time at constant temperature, and decrease with increasing temperature. The PMMA samples in vacuum were opened to air and the ESR spectrum was followed with time. It was observed that the nine-line spectrum converted into a line asymmetric spectrum in õ 1 min at room temperature.

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Low temperature reactions of polymeric free radicals. Addition to double bonds

Cited by 10 publications

References 10 publications

Mechanisms

Mechanisms

Depolymerization of Polymethacrylates with Ball-Mill Grinding

An electron spin resonance study of mechanical fracture of poly(methyl methacrylate)

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