G. N. Gubanova

Polyrotaxanes composed of β-cyclodextrin and polydimethylsiloxanes: synthesis, morphology and thermal behavior

Epoxy-terminated polydimethylsiloxanes (E-PDMSs) of different molecular weight M n were proved to undergo inclusion complexation into the inner cavity of β-cyclodextrin (β-CD), resulting in polyrotaxanes (PRots). The dethreading of the macrocycle was prevented by blocking the siloxane chain with a bulky substituent derived from 4-aminophenyltriphenyl methane (APhTPhM). As revealed by thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy (SEM), wide-angle X-ray diffraction and statistical analysis of SEM images, the thermal properties and the morphology of polyrotoxanes are dependent upon M n, β-CD/E-PDMS molar ratio and the presence of free β-CD in the complexes.

Nanocomposites Based on Aromatic Polyamide-Imide and Magnesium Hydrosilicate Nanotubes

Structure, morphology, and thermal properties of nanocomposites based on thermally stable poly(diphenyloxydamide-N-phenylphtalimide) (PAI) and layered magnesium hydrosilicate nanotubes (NTs) were studied using thermogravimetric analysis, dynamic mechanical analysis, atomic force microscopy, and differential scanning calorimetry. Thermal stability and glass transition temperature of the composites were shown to exceed those of the PAI matrix. Introduction of NT into the polymer matrix appreciably increased the elasticity and deformability of the composite material. The content of NT was also shown to greatly influence the surface morphology of the PAI-NT composites.

Structure, morphology, and thermal properties of nanocomposites based on polyamido imide and hydrosilicate nanotubes

New nanocomposites based on heat-resistant poly[(diphenyl oxide)amido-N-phenylphthalimide] with Mg3Si2O5(OH)4 hydrosilicate nanoparticles of tubular structure were prepared. The structure, morphology, and thermal properties of the nanocomposites were studied in relation to the content of hydrosilicate nanotubes.

Morphology and mechanical properties of polymer-inorganic nanocomposite containing triple chain fibrous Na-Mg hydrosilicate

A polymer-inorganic nanocomposite of fibrous Na-Mg triple chain hydrosilicate and polyamidoimide based on 4-chloroformyl-(N-p-chloroformylphenyl)phthalimide and 4,4′-diaminodiphenyl ether has been developed. Morphology and dynamic mechanical properties of the nanocomposite films have been studied. Anisotropy of mechanical properties of the nanocomposite and the pristine polyamidoimide films has been revealed. Introduction of the fibrous filler disrupts the ordered mesomorphic structure of the polymer matrix; its recovery upon heating above the glass transition temperature is possible.

Aromatic Polyimide/MWCNT Hybrid Nanocomposites: Structure, Dynamics, and Properties

Two series of hybrid polyimide (PI)/multiwalled carbon nanotube (MWCNT) nanocomposites were prepared including COOH-functionalized or pristine nanotubes, and their structure, morphology and dynamics/mechanical properties at 20°C–500°C were studied using WAXD (Wide-angle X-ray diffraction), AFM (Atomic force microscopy), TEM (transmission electron microscopy), DSC (Differential scanning calorimetry), DMA (Dynamic mechanical analysis), CRS (creep rate spectroscopy) techniques, and stress–strain testing. The impact of nanofiller loadings of 0.125, 0.25, 0.5, or 1 wt% relative to PI was evaluated. Specific changes in the matrix morphology and different quality of nanotube dispersion in the nanocomposites with amorphous and semicrystalline matrices were determined. The best nanotube dispersion was observed in the composites with 0.5 wt% MWCNT-COOH. A peculiar high temperature dynamics, different for amorphous, and semicrystalline matrices, was revealed in these nanocomposites. The most dramatic changes in high temperature dynamics and a pronounced dynamic heterogeneity as well as substantially enhanced mechanical properties at room temperature were revealed in the case of a semicrystalline PI matrix. The results were treated in terms of the synergistic impact of nanotubes and matrix crystallites on dynamics in the intercrystalline regions of PI (“combined constrained dynamics effect”) and the peculiar interfacial dynamics.

Aromatic polyamidoimides modified with hydrosilicate nanoparticles of different structure and morphology for membrane technologies

New organic–inorganic composites based on aromatic polyamidoimide with ribbon-like particles of fibrous triple chain Na2Mg4Si6O16(OH)2 hydrosilicate have been obtained with the subsequent characterization of their structure, morphology, and transport properties. A comparative analysis of polyimide composites with ribbon-like Na2Mg4Si6O16(OH)2 hydrosilicates and tubular Mg3Si2O5(OH)4 hydrosilicate nanoparticles has been implemented.

Effect of carbon nanostructures on the carbonization of polyacrylonitrile

Composite materials based on polyacrylonitrile with carbon nanofillers (technical-grade carbon, thermally expanded graphite, carbon nanotubes) were synthesized. A carbonization of film and fiber composite samples in the temperature range 20–1000°C provided a noticeable increase in the thermal stability of fibers and a rise in the electrical conductivity of the composite material. Dependences of the degree of carbonization on the concentration of nanostructures, type of material, and nature of modifier were determined. Differential-thermal and X-ray diffraction analyses revealed the formation of oriented nucleus structures of turbostratic carbon in the temperature range 450–550°C.

Structure, Morphology, and Thermal Properties of Polyrotaxanes Based on Calix(6)arene and Modifi ed Polydimethylsiloxane

New supramolecular inclusion complexes, polyrotaxanes derived from p-tert-butylcalix[6]arene and polydimethylsiloxane modified with terminal epoxy groups, were synthesized and studied. The dependence of the structure, morphology, and thermal properties of polyrotaxanes on the molecular weight of the linear polymer was determined.

Structure and thermal properties of polyrotaxanes derived from γ-cyclodextrin and modified polydimethylsiloxane

Supramolecular inclusion complexes, polyrotaxanes, derived from γ-cyclodextrin and polydimethylsiloxane modified with terminal epoxy groups were studied. The dependence of the structure, morphology, and thermal properties of polyrotaxanes on the molecular weight of the linear polymer, molar ratio of γ-cyclodextrin and polymer, and presence of free γ-cyclodextrin in the complexes was examined.

Thermal Transformations of Polyoxadiazoles

Changes of the structural characteristics and electrical properties of fibers based on polyoxadiazole (Arselon) upon a low-temperature thermal treatment in an inert atmosphere were studied. Extremal dependences of the conductivity of the fibers on treatment temperature were observed and a mechanism of this process was suggested. The X-ray diffraction parameters of the Arselon fibers were determined for the extreme states and practical recommendations were made for using a preliminary heating of the fibers.