Electron Spin Resonance Spectra of Free-Radical Intermediates Formed by Reaction of Polystyrene with Atoms of Hydrogen and Deuterium

“…During the reaction of atomic hydrogen with different organic compounds 421 , 465, 1961,1962), synthetic polymers144, 574,575,579,582,583,1001,2182,2376,2377,2381,6. ESR Study of Polymers in Reactive Gases 2382) and biopolymers 930 .…”

Section: Atomic Hydrogenmentioning

confidence: 99%

ESR Spectroscopy in Polymer Research

Rånby¹,

Rabek²

1977

Polymers Properties and Applications

294

118

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“…Solids investigated at room temperature are polymer "fl~luffs" (1,2), suspensions on quartz wool (3, or pure finely divided powders (4)(5)(6)(7); some compounds which are liquid at room temperature have been bombarded with atoms in the frozen state (8)(9)(10). Heterogeneous reactions with adsorbed molecules have been very few.…”

Section: Introductionmentioning

confidence: 99%

Reactions of alcohols adsorbed on MgO. Part I. Heterogeneous reactions with hydrogen atoms and trapped electrons at room temperature: a new technique in surface chemistry

Smith¹,

Tench²

1969

Can. J. Chem.

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A series of alcohols, adsorbed on MgO powder, have been bombarded by a stream of hydrogen atoms at room temperature and the radicals thus formed are detected by electron spin resonance. Methanol, ethanol, rz-propanol, iso-propanol, n-butanol, see-butanol, and ally1 alcohol have been studied. The radical species produced have been identified and radical lifetimes varying fro111 ininutes to hours at 300 'K have been observed. For methanol, the first nionolayer appears to be chemisorbed as inethoxy groups ~vhereas the ethanol data indicate that some of the molecules in the first monolayer are physically adsorbed. The higher alcohols form secondary radicals via hydrogen elimination from the primary radical; the isopropyl alcohol radical appears to isomerize before losing hydrogen. Ally1 alcohol undergoes hydrogen atom abstraction in preference to addition to the double bond and yields the a-hydroxy-ally1 radical. Methanol and ethanol have also been reacted with electrons trapped on a MgO sarface to form stable alkoxide ion radicals trapped at oxygen ion vacancies on the surface of the lattice.

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“…These studies include the bombardment of both low molecular weight solids1"6 and polymeric solids. 7,8 The experiments described here, involving the hydrogen/ deuterium atom bombardment of monomers and polymers, were undertaken to better understand the free-radical cross-linking mechanisms in maleimide and bismaleimide polymers. We are using electron spin resonance (ESR) techniques to identify the free-radical intermediates involved in these cross-linking reactions and, in so doing, to verify our spectral assignments for the radicals that we have observed previously9 in the hot-melt homopolymerizations of maleimides and bismaleimides.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen-atom bombardment of monomers and polymers: maleimides, bismaleimides, and succinimide

Brown¹,

Sandreczki²

1990

Macromolecules

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Electron spin resonance experiments are described which involve the bombardment of succinimide, substituted maleimides, and a substituted bismaleimide with hydrogen and deuterium atoms. Several different types of maleimide radicals, viz., the initial radical, the propagating radical, the penultimate radical, the backbone radical, and the vinyl radical, have been observed during and after termination of the microwave discharge used to generate the bombarding atomic species. These radicals have been identified by way of the hyperfine structure in their spectra observed under the appropriate experimental conditions. In some cases the spectral line widths decreased with time after the microwave discharge was terminated because radical concentrations close to the crystallite surfaces were reduced by hydrogen atom spatial diffusion and/ or radical decomposition. In the hydrogen atom bombardment of aliphatic maleimides and bismaleimides, the radical reactions occurred exclusively a t the maleimide double bond, whereas in aromatic maleimides and bismaleimides several types of cyclohexadienyl radicals were formed in addition to the maleimide radicals.

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Electron Spin Resonance Spectra of Free-Radical Intermediates Formed by Reaction of Polystyrene with Atoms of Hydrogen and Deuterium

Cited by 31 publications

References 3 publications

ESR Spectroscopy in Polymer Research

ESR Spectroscopy in Polymer Research

Reactions of alcohols adsorbed on MgO. Part I. Heterogeneous reactions with hydrogen atoms and trapped electrons at room temperature: a new technique in surface chemistry

Hydrogen-atom bombardment of monomers and polymers: maleimides, bismaleimides, and succinimide

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