The topic of this presentation concerns to create polymeric nanocomposites using distinctive polymers (amorphous and semicrystalline) and unmodified and organically modified clays, and investigate relations between the properties and the obtained materials and fillers concentration. As polymer matrices are chosen polypropylene, styrene acrylate copolymer, acrylic-vinylacetate-acrylnitrile copolymer, polyvinyl alcohol. Then as filler are used natural and organically modified monmorillonite nanoclays. Nanocomposites are prepared using solution, emulsion and melt blending techniques that corresponds to initial state of the polymer. Relatively to the preferred dispersion methods, montmorillonite nanoclays are utilized in different condition state – water or solvent dispersions and powders. Nanoclays are modified with different chemical structure organic compounds. Therefore, at all set of 4 polymers and 5 nanoclays are used. Materials with filler concentration from 0 till 15 wt.% (7 vol.%) are prepared in the state of films and granules. Structure-property-preparation relationships of the nanocomposites are examined considering micro- and nano-structure of the nanocomposites. Mechanical, thermal and permeability properties of the prepared materials are discussed. General conclusions are done about influence of polymer state (glass, rubber) and morphology (amorphous, semicrystalline) on the nanocomposites properties. We can conclude that exist many similarities of property improvements in examined nanocomposites that generally are independent from nanocomposites preparation method. The data of x-ray diffraction analysis indicates the exfoliation of clay platelets in rather low concentration of filler (up to 3 wt.%). Further increasing the filler content, the most part of the clay platelets remain in the state of the swelled lamina stacks, whose interlaminar galleries distances are equal to the thickness of the penetrated polymer layer. Obtained experimental results showed that nanocomposites are described with considerable increase in elasticity, strength, thermal stability, and also decrease in flammability, permeability. Micromechanical modelling of inherent elasticity constants used to describe nanocomposites structure-property regularities is proposed in [1]. The experimentally obtained barrier properties of the nanocomposites are calculated using analytical model taking into account the shield effect of platelet particles [2].