E. N. Popova

Distribution of zirconia nanoparticles in the matrix of poly(4,4′-oxydiphenylenepyromellitimide)

Poly(4,4′-oxydiphenylenepyromellitimide) is used as a polymer matrix for incorporation of zirconia nanoparticles with different compositions (ZrO2 and Y0.03Zr0.97O1.985), sizes (20 ± 5 and 10 ± 2 nm), and morphologies (spheres, hollow spheres, rods). The nanoparticles are incorporated during the synthesis of poly(amido acid), a prepolymer of polyimide, and ZrO2 nanoparticles are pretreated with organosilicon compounds (tetraethoxysilane, γ-aminopropyltriethoxysilane, and 3-(trimethoxysilyl)propyl methacrylate). The effect of surface modification of ZrO2 nanoparticles on their distribution in poly(4,4′-oxydiphenylenepyromellitimide), depending on the type of the organosilicon compound as well as on the dispersity, shape, and chemical composition of particles, is studied.

Composites of multiblock (segmented) aliphatic poly(ester imide) with zirconia nanoparticles: Synthesis, mechanical properties, and pervaporation behavior

On the basis of pyromellitic dianhydride, p-phenylenediamine, and poly(butylene adipate) diol (Mn n = 1 × 103) and poly(ethylene adipate) diol (Mn n = 1 × 104) taken at a molar ratio of 10 : 1, initial samples of multiblock poly(ester imide) and its composites with nanoparticles of two types—zirconia ZrO2 surface-treated with γ-aminopropyltriethoxysilane and zirconia doped with yttria (Y0.03Zr0.97O1.985)—are synthesized. Nanoparticles are introduced into the polymer matrix at the stage of synthesis of the poly(ester imide) prepolymer. The mechanical properties of films of poly(ester imide) and its nanocomposites are determined under static and dynamic testing conditions, and the permeabilities and separation selectivities of corresponding solid films for mixtures of aromatic and aliphatic hydrocarbons (toluene-n-octane and benzenecyclohexane) of various compositions are measured under pervaporation testing conditions. It is shown that the different mechanical and pervaporation properties of film samples are due to the presence of zirconiabased nanoparticles.

Optically active polyamidoimides based on amino acids containing cyclohexane fragment

New amino carboxylic acids containing a cyclohexane fragment and an L-leucine or L-valine fragment were synthesized. The reactions of the synthesized amino acids with 4,4′-oxydiphthalic anhydride gave in quantitative yields the dicarboxylic acids, which were converted to the corresponding dichlorides. Low-temperature polycondensation of the synthesized dichlorides with 4,4′-diaminodiphenyl ether yielded optically active polyamidoimides, which are soluble in various organic solvents and exhibit enhanced heat resistance. The structures of the synthesized monomeric compounds and polymers were confirmed by elemental analysis, IR and 1H NMR spectroscopy, and high-resolution mass spectrometry. Specific rotation angles of the synthesized amino carboxylic acids and polyamidoimides were determined.

Properties of solutions of methyl cellulose blends with poly( N -methyl- N -vinylacetamide) in water and dimethylacetamide and of the related composite films

The rheological properties of dilute and moderately concentrated solutions of methyl cellulose blends with poly(N-methyl-N-vinylacetamide) in water and dimethylacetamide are studied, and the stressstrain characteristics of the composite films based on these blends are estimated. DSC, X-ray diffraction, and thermomechanical analysis are used to investigate the structural organization of composite films, to estimate the temperatures of relaxation transitions, and to determine the composition ranges in which the polymers are compatible and form mixed structures.

Structure and characteristics of film composites based on methyl cellulose, poviargol, and montmorillonite

The structure of film composites based on methyl cellulose and fillers, such as montmorillonite and silver nanoparticles stabilized by poly(vinylpyrrolidone) (Poviargol), is studied by X-ray diffraction. In the composite, montmorillonite nanoparticles exist in the exfoliated state; when the content of the nanoparticles is below 7 wt %, the crystallinity of methyl cellulose increases. Owing to the presence of the filler and structural ordering of the matrix, elastic characteristics improve and the degradation temperature of the composites increases. The X-ray structural data show that the Ag particles in the methyl cellulose-Poviargol composite are 30 nm in size. The introduction of up to 20 wt % Poviargol assists the crystallization of methyl cellulose. The strength and strain characteristics of the film composites based on methyl cellulose and Poviargol make it possible to use these composites in medicine and agriculture.

Effect of nanoparticles of various types as fillers on mechanical properties of block samples of a heat-resistant polyimide material: A comparative analysis

A comparative study of the effects of various nanoparticles introduced into polyetherimide Ultem-1000 (Sabic)—such as carbon nanofibers, nanocones/discs, halloysite hydrosilicate nanotubes, and quasispherical zirconia particles doped with yttria―on the mechanical behavior of nanocomposites is performed. The introduction of nanoparticles into the polymer increases the Young’s moduli and yield stress of block materials relative to those of the unfilled polymeric material. These effects make themselves more pronounced with an increase in temperature, especially when сarbon nanocones/discs are used as a filler. The collected data are commensurable with the electron-microscopic study of the morphology of the material and its densitometry measurements, which make it possible to estimate the values of excess free volume in the studied composite materials, as well as with the previous data on the incorporation of analogous nanoparticles into polypyromellitimide films.

Structure formation, stability, and thermal strain behavior of oriented microporous polypropylene films

Oriented porous polypropylene films subjected to thermal fixation under isometric conditions were prepared and studied. The thermal fixation parameters ensuring the stability of the pore structure of the specimens were determined. The film permeability as a function of the thermal fixation temperature passes through a maximum at ∼130°C. The behavior of the free porous specimens on heating was studied, and the changes in the permeability and pore structure characteristics in the course of the film shrinkage were determined.

Rheological properties of mixtures of cellulose with chitin in 1-butyl-3methylimidazolium acetate of the obtained composite films obtained

Rheological properties of solutions of cellulose mixed with chitin in 1-butyl-3-methylimidazolium acetate were studied. Positive and negative deviations of values of the viscosity and activation energy Ea of viscous flow from additive values were observed. X-ray diffraction and thermogravimetric analyses were used to examine the structural organization and the thermal stability of the composite films obtained.

Carbon-reinforced plastics based on hybrid polyimide-organosilicon binders

Compounds based on the synthesized polyimides and organosilicon resins were developed. The compatibility of organosilicon resins with polyimide binders was studied by electron microscopy. The possibility of preparing fibrous composite materials, carbon-reinforced plastics, using such polyimide-organosilicon binders was demonstrated. The viscoelastic and strength properties of the materials obtained were studied. The optimum binder composition, ensuring 90% preservation of the elastic modulus and 70% preservation of strength of the carbon-reinforced plastic relative to the initial values after keeping in air for 50 h at 350°C, was chosen.

Iridium metal–polymer complexes based on bipyridyl ligands

Novel polymer macroligands—copolyamides containing different quantity of bipyridyl groups—were obtained from 4,4′-diamino-2,2′-bipyridine, 4,4′-diaminodiphenyl ether and terephthaloyl-bis(3-methoxy-4-hydroxybenzoic) acid dichloroanhydride by low-temperature polycondensation. Metal–polymer complexes with different content of Ir(ppy)2 were obtained by the interaction between polymer ligand and [Ir(ppy)2Cl]2 (ppy–2-phenylpyridine). The properties of films and coatings based on these materials were studied.