ИСТИНА

Graphite oxide membranes (GOM) are materials with versatile useful properties. Nevertheless many details of internal structure of the membranes are still unclear. Until now the orientational ordering of the planes in GOMs was studied only visually by cross-sectional SEM imagines. We showed that the ordering of GOMs can be investigated quantitatively us-ing spin probe technique [1]. The present work is devoted to quantitative characterization of the orientational order of the graphite oxide membrane fabricated by vacuum filtration. Spin probes TEMPO, TEMPOL, and 4-aminoTEMPO were used for this purpose. The radicals were introduced into the mem-brane from acetonitrile. It was revealed that 4-aminoTEMPO cannot be further removed by washing the membrane with acetonitrile or water as opposed to TEMPO and TEMPOL. The slower rotational mobility of 4-aminoTEMPO, sorbed on inner surface of the membrane, compared with TEMPOL was also found. These facts were interpreted as site-specific bind-ing of 4-aminoTEMPO molecules with carboxylic groups of GOM. Analysis of angular de-pendences of EPR spectra (Fig.1) showed that orientational ordering of 4-aminoTEMPO in the membrane is significantly less than ordering of TEMPOL. Apparently, 4-aminoTEMPO mainly reflects the alignment of the membrane areas containing carboxylic groups, while TEMPO and TEMPOL characterize the average orientation of the membrane.