Properties of thin polyethylene glycol layers on the surface of silica geland pyrocarbon/silica gel - Effect of topography and morphology of carbon deposit

The structural and energetic heterogeneity of silica gel and pyrocarbon/sil ica gel adsorbents was studied by means of the adsorption methods. The prop erties of polyethylene glycols (PEG 4000, PEG 1500) in a mixture with the s olid adsorbents have been investigated using different probe molecules for gas chromatography. The carbosils investigated possessed a mosaic structure due to carbon deposit distribution features. The mechanism of formation of polyethylene glycol layers on the carbosils surface depends on the chemica l structure and amount of pyrocarbon. Chemical and structural heterogeneity of the adsorbent surface is of great importance in this case. From the pra ctical point of view, it was interesting to study the effect of such hetero geneity on the selectivity of the chromatographic columns in relation to th e model mixtures. (C) 2001 Elsevier Science B.V. All rights reserved.