Gigiberiya V. The processes self-assembly in liquids filled by nanoparticles with anisotropic shape

The thesis is devoted to the experimental and theoretical studies of self-assembly liquids processes in anisotropic forms filled by nanoparticles with anisotropic shape. In the experimental part, the influence of surfactants additives (CTAB, Triton-X165) on the drying of droplets and the formation of a "coffee ring" structures was investigated. For aqueous nanofluids on the base of laponite (Laponite RD) "coffee ring" structure we formed. The stages of drying include the drying of bulk liquid phase (phase I), the formation of the ring and drying of gel phase of laponite (stage II) and the formation of a dense gel in the volume of the droplet (stage III). For aqueous nanofluids on the base of NT and cationic surfactant CTAB the different morphological types of dried residues were observed in dependence on the degree of coverage of NTs by CTAB, FCTAB. For partially stabilized nanofluids (at FCTAB ≈0.8) porous aggregates of NTs and significant "coffee rings" were formed. For well-stabilized fluids (at FCTAB > 1) the structures with a wide "coffee rings", and a semi-transparent and uniform film in the droplet centre were formed. The processes of nanoparticle self-assembly during the drying of the droplets of organic nanofluids (iso-propanol, p-xylene, toluene) on the base of NTs in the presence of nonionic surfactant Triton X-165 were investigated. For nanofluids on the base of iso-propanol and toluene the formation of dry residues did not displayed significant "coffee ring"-like structures. With additives of Triton X-165 the aggregation stability of nanofluids and untransparency of the dried residues were significantly dependent on the type of organic solvent. The Monte Carlo studies of the processes of self-assembling of rods (linear particles, k-mers) for two lattice two-dimensional models (diffusion motion and vertical drying) were performed. For the diffusion motion model for relatively long rods (with a length ща k≥6) self-assembly was manifested as formation of diagonal stripe domains that combine rods of different orientations. For the vertical evaporation model a significant orientation segregation of the rods controlled by diffusion motions of rods and evaporation processes was observed. Drying led to significant stratification and the formation of domains with different orientation of the rods. The dried films formed as a result of the vertical drying exhibited a significant anisotropy of electrical conductivity, which depends on the velocity of evaporation, the length of the rods and their initial concentration.