## 1 Introduction  
High performance (thermoplastic) polymers (HPP), such as polyimide (PI) and polyetherimide (PEI), are characterized by great mechanical properties in wide temperature ranges. They attract designers of polymer nanocomposites for antifriction applications. However, despite all their inherent advantages, neat polyimides are almost not employed for manufacturing parts of tribological units due to their fast wearing under dry sliding friction conditions because of the high strength and coefficient of friction (CoF) levels [1; 2; 3]. Typically, this issue is solved by loading with solid lubricant fillers, which enables a reduction of reduce both the CoF and wear rate (WR) values for the mating parts. [PERSON] et al. [4] noted that the friction process and wear performance depend on the formation, development and stability of a transfer film, in addition to the structure and composition of such solid lubricants. The most common ones include polytetrafluoroethylene (PTFE) [5; 6], graphite (Gr) [7], molybdenum disulfide (MoS\({}_{2}\)) [8; 9], tungsten disulfide (WS\({}_{2}\)), boron nitride (BN), etc. [PERSON] et al. [10] showed that transfer films (TFs) can have a gradient structure: PTFEis on their surfaces, while polyetheretherketone (PEEK) is mostly in the bulk. In addition, [PERSON] et al. reported [11] that sliding-induced chemical changes contribute to the formation of direct polymer/filler and polymer/counterpart bonds, stabilizing the surfaces by adhering the transfer film (TF) on a counterpart. Recently, the attention of many researchers was riveted to the design of nanocomposites based on various polymer matrices. A monograph edited by [PERSON] [12] was one of the first most comprehensive steps in this direction. This book and other reports [13; 14; 15; 16] devoted to the study of the tribological characteristics of nanocomposites have justified that nanofillers can significantly affect the functional properties of TFs. In this way, loading PEEK with 1 vol.% nano-SiO\({}_{2}\) improved the wear resistance of a nanocomposite via the fast formation of a tribological film. Such a nanocomposite possessed a WR level of -9 \(\times\) 10\({}^{-6}\) mm\({}^{3}\)/N\(\cdot\)m that was 69% greater in comparison with neat PEEK [17]. In [18], [PERSON], et al. reported the effect of decorated reduced graphene oxide (GO) synthesized with 3-Triethoxysilypropylamine on the tribological properties of PI-based composites. At a content of 0.5 wt.%, the WR value was 2.64 \(\times\) 10\({}^{-6}\) mm\({}^{3}\)/N\(\cdot\)m. According to the authors of [18], the nanoparticles inhibited the propagation of a crack during the friction process, lowering the WR level. Similar results were obtained for another PI-based composite, when [PERSON], et al. [19] investigated the influence of Fe\({}_{2}\)O\({}_{3}\)-decorated reduced GO. In addition, [PERSON] et al. [20] reported the effect of h-BN and amorphous SiO\({}_{2}\) nanoparticles on TF formation on PI-based nanocomposites loaded with both carbon fibers (CFs) and graphite. Filling with such nanoparticles significantly inhibited the tribo-oxidation process and improved the tribological performance. Carbon nanomaterials are widely used as additives for fabricating bulk composites due to their great physical-chemical properties [21; 22]. Various nanoparticles are widely employed for antifriction applications as well [23]. Carbon nanotubes (CNTs), as an antioxidant, were studied in [24], where their efficiency was proven for PEEK at temperatures up to 450 \({}^{\circ}\)C. [PERSON] et al. reported [25] that, compared with neat PI, the thermal stability and heat resistance of composites were increased by 10 \({}^{\circ}\)C after loading with 5 wt.% nano-SiO\({}_{2}\). At the same time, both their compressive strength and elastic modulus values were enhanced by 42.6% and 45.2%, respectively. Diez-Pascual and Diez-Vicente fabricated PEEK/PI-based nanocomposites reinforced with TiO\({}_{2}\) nanoparticles [26].