K. A. Romashkova

Polymer-inorganic nanocomposites based on aromatic polyamidoimides effective in the processes of liquids separation

The polymer-inorganic nanocomposites based on the aromatic polyamidoimides and the silicate nanotubes of chrysotile structure were developed. The polyamidoimides were synthesized from dicarboxyphenylphthalimide dichloride by the polycondensation with either 4,4′-diaminodiphenyl ether or 3,5-diaminobenzoic acid. The morphology, mechanical and transport properties of the nanocomposite films were studied. Distribution of nanotubes in the composites is shown to be defined by the chemical structure of the polyamidoimide. The conditions for the formation of the composites were optimized to provide a significant increase in selective permeability toward alcohol and water in the process of pervaporation at the introduction of the nanotubes in the polymer.

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.

Aromatic polysulfone imides and membranes based on them

Aromatic polyimides containing diphenyl sulfone fragments in the backbone were prepared. Asymmetric microporous films of the synthesized polymers were prepared by wet forming under the conditions of a phase-inversion process. The morphologies and the mechanical and transport properties of nonporous and phase-inversion films as materials for pervaporation membranes were studied. Multilayer composite membranes with diffusion layers of an aromatic polyether imide were prepared on the basis of microporous polyamido imide films. These membranes showed high performance in pervaporation separation of ethanol-cyclohexane mixtures of various compositions.

Phase-inversion gradient-porous films on the basis of polyamidoimides derived from phthalimidobenzenedicarbonyl dichloride and various diamines

Morphology of microporous films prepared from aromatic polyamidoimides under different molding conditions was studied by scanning, transmission, and atomic force microscopy with the specific attention given to the nanosize skin layer. The films were manufactured by the phase inversion molding of aromatic polyamidoimides which were synthesized by low-temperature polycondensation of phthalimidobenzenedicarbonyl dichloride with various diamines. Comparison of the parameters of films, including their wettability and X-ray photoelectron spectroscopy data, gave additional information on factors affecting the mechanism of formation of microporous membranes in the system polymer (polyamidoimide)-solvent (N-methylpyrrolidin-2-one)-non-solvent (water).

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.

Two-Ply Composite Membranes with Separation Layers from Chitosan and Sulfoethylcellulose on a Microporous Support Based on Poly(diphenylsulfone-N-phenylphthalimide)

Two-ply composite membranes with separation layers from chitosan and sulfoethylcellulose were developed on a microporous support based on poly(diphenylsulfone-N-phenylphthalimide) and investigated by use of X-ray diffraction and scanning electron microscopy methods. The pervaporation properties of the membranes were studied for the separation of aqueous alcohol (ethanol, propan-2-ol) mixtures of different compositions. When the mixtures to be separated consist of less than 15 wt % water in propan-2-ol, the membranes composed of polyelectrolytes with the same molar fraction of ionogenic groups (-NH3+ for chitosan and -SO3− for sulfoethylcellulose) show high permselectivity (the water content in the permeate was 100%). Factors affecting the structure of a non-porous layer of the polyelectrolyte complex formed on the substrate surface and the contribution of that complex to changes in the transport properties of membranes are discussed. The results indicate significant prospects for the use of chitosan and sulfoethylcellulose for the formation of highly selective pervaporation membranes.

Relaxation processes in an aromatic polyamide-imide and composites on its basis with hydrosilicate nanoparticles

Features of the relaxation behavior of an aromatic polyamide-imide and a composite with nanotubes of magnesium silicate with the structure of chrysotile have been studied by dynamic mechanical analysis, dielectric spectroscopy, and differential scanning calorimetry. Two secondary relaxation (β1 and β2) transitions have been found, the activation energies of these processes have been determined, and the solvent effect on the cooperativeness degree has been studied. Changes in the value of the apparent activation energy of the β1-process caused by the subsequent heating of polymeric and composite samples have been analyzed according to the Starkweather procedure. It has been shown that, as the solvent is released from the polyamide-imide film, the polymer exhibits increasing local mobility, which are predetermined by the structure of the molecular unit. Using the GAMESS software, we have assumed the most probable dimer conformations that correspond to two repeating units of the polyamide-imide molecule.

Analysis of the surface morphology, structure and properties of polyamidoimide nanocomposites with tubular hydrosilicates

The surface morphology, structure and transport properties of polyamidoimide (PAI) films prepared from poly(diphenyloxidiamido-N-phenylphtalimidene) synthesized by low temperature polycondensation, and composites with chrysotile-type hydrosilicate nanotubes (NTs) based on it are investigated using АFМ (atomic force microscopy), X-ray diffraction analysis and pervaporation methods. The dependence of the free surface morphology of PAI films on their thicknesses is found: the minimal value of the roughness parameters is achieved at a film thickness of 15 μm, in this case the minimal value of the sizes of macromolecular “nodules” is also recorded, which is 50 nm. It is established that upon the introduction of NTs up to 7 wt % into PAI films with a thickness of 35 μm, the mesomorphic polymer structure is retained. An antibatic dependence of the nanocomposite transport characteristics on surface roughness parameters is detected. The maximal value of the ideal separation factor for a methanol-cyclohexane mixture is demonstrated to correspond to a composite containing 1 wt % of NTs and possessing minimal values of the surface-roughness parameters.

New composite materials based on polyvinylpyrrolidone and poly(diphenyl oxide amido-N-phenylphthalimide)

With the use of X-ray diffraction analysis, differential scanning calorimetry, dynamic mechanical analysis, and ATR FTIR spectroscopy, the structures and mechanical and thermophysical properties of composite films of various compositions obtained on the basis of polyvinylpyrrolidone and poly(diphenyl oxide amido-N-phenylphthalimide) are investigated. At all component ratios, these polymers form a complex via a system of hydrogen bonds during the formation of composites from solution. The best compatibility of blend components is attained at a polymer ratio of 1: 1, at which individual phases of initial components are absent. The temperatures of glass transition and of other thermal transitions of the samples are determined. Structural changes occurring in the films before and after pervaporation are studied. The considered membranes may show promise for the separation of liquids only in the case of the predominant formation of an interpolymer complex stable during the transport of penetrates of various polarities, such as cyclohexane or water, across the membrane.