## 2 Polymer Nanocomposites for Membranes Applications
In this property (an increase in permeability to liquids upon introduction of inorganic nanotubular additives), the PAI-1-SNT-II (20) composite material obtained strongly differs from typical composites constituted by a polymer and an inorganic filler. As a rule, introduction of inorganic particles into a polymeric matrix results in an inorganic phase impermeable to gases and liquid is formed in the matrix and the mass-transfer zone becomes narrower. As a result, the permeability on nonporous films falls. For this reason, introduction into the PAI-1 matrix of 2 wt % MMT-15A particles under the same conditions yields a composite material with lowered permeability, as shown in Table 3. Because inorganic MMT-15A particles and SNT are close in chemical composition, no other components are present in the systems under consideration, and the formation conditions were similar, it can be assumed that the nano-size structural features of the films exert a decisive influence on their transport properties. The properties of the filled polymers resulting from the processes of distribution of nano-sized inorganic particles in them appear to be determined not only by the new structural characteristics of the composites, but also by factors such as the number and nature of the reactive groups of the components, and also the presence of fragments in the polymer structure that can serve as \"potential ligands\" for the selected filler. Therefore, a comparative study was of interest of the structure and transport properties of nanocomposites formed by the introduction of inorganic NTs into the polymers of different chemical structure. The non-porous composite films based on the aromatic PAIs differing by the structure of diamine component containing equal amounts of SNT were obtained and investigated in dependence to the structure and transport properties [121]. The main reason for the choice of these nanoparticles was the chemical composition of their surface, namely, the presence of the reactive polar hydroxyl groups. Moderately hydrophilic PAIs, characterized by the ability to interact with the functional groups of magnesium-SNTs, as well as to interact with the solvents used as penetrating substances, were studied in the pervaporation process. It became possible to study the influence of functionalization of the polymer matrix on the morphological and transport properties of formed nanocomposites. In the paper [121], the transport properties of PAI-1 and PAI-1-SNT were examined at the pervaporation in relation to a wide range of penetrating substances (water, methanol, cyclohexane, and methyl-_tert_-butyl ether). It is unclear up today how is formed and where is located the \"priority transport channel\" for the more polar components of the penetrating mixture. An assumption seems correct about the special role of the hydroxyl-groups located on the outer surface of the used SNT, that it is able to interact with both amide and imide groups of the PAI-1, and with the polar groups of the transported molecules (water, alcohols). If this assumption was correct, then the introduction in the polymer chain of the functional groups capable to form hydrogen bonds with hydroxyl-groups or water dipoles should affect the transport properties of the composites. To test this hypothesis, the composite PAI-2-SNT-II that differs from PAI-1-SNT-II by the structure of the polymer diamine component and contains carboxy-groups of diaminobenzoic acid (PAI-2) was obtained. Figure 24 shows microphotographs of (a) upper and (b) lower surfaces of the film PAI-2-SNT-II. It was shown that, as in the case of PAI-1-SNT-II, the lower surface of the film has a distinct grain structure, unlike the smoother upper surface. On both surfaces at the zoom 18,000 NTs were not found freely \"lying\", nor their fragments. All NTs were in the inner layers of the composite film.