One functionally graded nanocomposite "PTFE - metal oxide" has been studied in the paper "Estimation of the Friction Coefficient of a Nanostructured Composite Coating // Mechanics of Composite Materials. – 2017. – Vol. 53, No. 5. – P. 579–588" where the gradient polymer-ceramic coating was obtained by gas-phase impregnation of nanoporous anodic oxide with a fluoropolymer (octafluorocyclobutane). The second example of functionally graded nanocomposite is described in paper of Popov A.N., et al. Mechanical and Antifrictional Properties of Elastomeric Composites Based on a Rubber for Sealing Elements // Mechanics of Composite Materials. – 2017. – Vol. 53, No. 4. – P. 505–514.