Liquid-like and solid-like acetonitrile intercalated into graphite oxide as studied by the spin probe technique

Abstract

Molecular mobility of acetonitrile intercalated into the inter-plane space of graphite oxide was studied using the spin probe technique. It was revealed that two types of intercalated substance – liquid-like...

Glass-like behavior of intercalated organic solvents in graphite oxide detected by spin-probe EPR

“…In ref. 20 we confirmed this observation for acetonitrile using the spin probe method with the continuous wave (CW) EPR technique. It was shown that all intercalated substances inside the GO sample containing 70% acetonitrile relative to equilibrium sorption at room temperature exhibited low molecular mobility, which has been referred to as a solid-like substance.…”

“…Earlier, the same pattern was observed for a sample containing 70% acetonitrile. 20 A further temperature increase leads to the growth of triplet lines, the fraction of which, according to our estimates, does not exceed 4% at 324 K and 12% at 341 K (see Fig. S2, ESI †).…”

“…The presence of a bulk acetonitrile solution in the B-GO–acetonitrile sample can be excluded because the sample was saturated below the equilibrium sorption value. 12,20 We attribute this transition to an intrinsic property of the confined solvent between GO layers.…”

“…The method of isopiestic saturation is described in ref. 20. Between measurements, the samples were stored in a refrigerator at 258 K.…”

“…21 For graphite oxide swollen in acetonitrile, this separate phase was not previously observed, 21 but we were unable to determine the localization of the probe molecules in the inter-plane space of swelled graphite oxide. 20 The reason is the low mobility of radicals, both adsorbed on the GO surface and localized inside the solid-like intercalated acetonitrile, and the low sensitivity of CW EPR spectra to such slow motions. At the same time, pulse EPR methods are sensitive to molecular motions of spin probes in the slow-motional regime, capable of distinguishing different types of motions, and also sensitive to molecular motions of the local environment.…”