PROPERTIES OF SOLID-LIKE ACETONITRILE IN BETWEEN  OXIDIZED GRAPHENE PLANES ACCORDING TO PULSE EPR  SPECTROSCOPY

Аствацатуров, Д.А.; Сырямина, В.Н.; Дзюба, С.А.; Чумакова, Н.А.

Авторы: Аствацатуров Д.А., Сырямина В.Н., Дзюба С.А., Чумакова Н.А.
Сборник: VIII International Conference “Atmosphere, Ionosphere, Safety” (AIS-2023)
Тезисы
Год издания: 2023
Место издания: ООО «АЛГОМАТ» Калининград
Аннотация: Graphite oxide (GO) is a layered material composed of graphene planes contained oxygen groups –carboxyl, hydroxyl, carbonyl, epoxy, etc. At the present time, graphite oxide swelled in polar liquids is of great interest. Earlier it was shown using differential scanning calorimetry that liquids intercalated into the inter-plane space of GO do not exhibit the melting/freezing phase transition that is characteristic for bulk liquids. This observation points to the fact that properties of the intercalated liquids differ significantly from those of the bulk liquids. Molecular mobility of polar liquids, mainly water, in between the GO planes was investigated using several experimental methods. However, literature data is incomplete and partially inconsistent. We firstly used the spin probe technique to investigate the mobility of liquids in between oxidized graphene planes. Continuous wave EPR experiments showed that there are at least two fractions of intercalated acetonitrile in the material, which differ significantly in their mobility. We will refer to these substances as liquid-like and solid-like. We wondered if solidlike acetonitrile is crystalline or glassy fraction. If it is crystalline, all slowly-moving spin probes would be sorbed on the inner surface of GO. If it is glassy, there will be the distribution of spin probes between the inner surface of GO and solid-like acetonitrile. (In this case, two types of slowly-moving spin probes would demonstrate different relaxation times). To distinguish these assumptions, we applied echodetected electron paramagnetic resonance (ED EPR) spectroscopy, which is sensitive to different types of molecular motions and allows us to evaluate its correlation times in the range of 10-3-10-9 s.We found out that the spin-echo signal of the stable nitroxide radical TEMPO sorbed on the inner surface of GO can be detected only at low temperatures due to short relaxation times of spin-probes. Apparently, this effect is due to the paramagnetic nature of GO. ED EPR spectra of TEMPO located in GO swelled in acetonitrile reveals the enhanced mobility of the radicals as compared with the vacuumed GO. This means that in the system GO – acetonitrile the radicals are predominantly localized in intercalated acetonitrile. So, intercalated acetonitrile is a glassy substance. Further, the numerical simulations of ED EPR line shape allow evaluating the character of molecular motions and correlations times and demonstrating the high potential of pulse EPR method for studying molecular mobility of liquids in between oxidized graphene planes
Добавил в систему: Аствацатуров Дмитрий Александрович

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PROPERTIES OF SOLID-LIKE ACETONITRILE IN BETWEEN OXIDIZED GRAPHENE PLANES ACCORDING TO PULSE EPR SPECTROSCOPYтезисы доклада

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