TYPES OF INORGANIC FLUOROCARBON POLYMER MATERIALS AND STRUCTURE{PROPERTY CORRELATION PROBLEMS

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The paper reviews published data on the structure and composition of two large classes of inorganic polymer fluorocarbon materials (IP FCMs), including high‐temperature (HT) and low‐temperature (LT) modifications of graphite fluorides and fluorographite‐like compounds CFx (x = 0.5 – 1.12$) and CF1+y (y = 0.08 – 1.33$) and intercalated fluorographite compounds (IFGCs) based on CxF (x < 2) matrices. According to X‐ray diffraction data, C1s and F1s X‐ray photoelectron spectroscopy (XPS), 13C and 19F NMR, CKα and FKα X‐ray spectroscopy, and IR and Raman spectroscopy, as well as MNDO calculations, the structure of monolayers and the properties of IP FCMs of C2F – CF1+y composition depend on the combination of C(sp3) – F fragments bonded to the sp2 fragments of the starting carbon matrices. The structure of high‐temperature CF1+y is specified by the presence of structurally isolated external and internal C(sp3)F2 groups located on the boundaries of C(sp3) – F skeleton monolayers and in the holes of their nanostructures, respectively. The enthalpy of formation of HT FCMs does not depend on the type of starting carbon material and is linearly proportional to the F/C atomic ratio; C(sp3)F and C(sp3)F2 groups are chemically indistinguishable in HT FCMs. Six models for the structure of C2F and C4F monolayers in LT FCMs are considered. The best agreement with spectroscopy and MNDO data is obtained using modified Yudanov–Gornostaev's model for C2F, in which alternating rows of graphitelike sp2 carbon fragments coexist with rows of bonded perfluorocyclohexane sp3 cells. For low‐temperature C24F–C2F, electric conductivity and C1s and F1s XPS data are generalized and composition–property diagrams are constructed. In this case, the conductivity, C1s and F1s XPS, and the interplanar distances in monolayers are explained using the concept of planarity of CxF monolayers and the ensuing ideas of semi‐ionic and semicovalent C=F bonds. For C4F · yA–C2F · zA compositions, 13C and 19F NMR data, C1s and F1s XPS, and IR data are accounted for by the predominant sp3 nature of the structure‐forming C=F bonds.