Almaz Kamalov

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• PhD
• Senior Researcher at Institute of Macromolecular Compounds, Russian Academy of Sciences

This paper presents the optimal mode of plasma treatment of chitosan films to increase the proliferative activity of dermal fibroblasts and osteoblasts. For plasma modification of films, a dielectric barrier discharge in a flat electrode system and a plasma jet configuration at atmospheric pressure were used. The structural and chemical changes of...

This work is dedicated to the development and investigation of the properties of low‐dielectric‐constant nonwoven materials obtained by electrospinning from a polyimide‐based polymer, PMDA‐ODA, which is composed of pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA). The influence of the molar mass of PMDA‐ODA on the structural, mechanical,...

In the 5G field, there is a growing demand for materials with ultra‐low dielectric constant values that are able to maintain their dielectric and mechanical characteristics in a wide range of temperatures and frequencies of electric fields. In this work, heat‐resistant composites based on the salt of polyamic acid from pyromellitic dianhydride PMDA...

The development of technology for modifying polymer materials using cold plasma is an urgent task, as traditional chemical etching leaves a toxic trace that can harm cell viability. The purpose of this work is to modify the surface of composite films composed of chitosan and hydroxyapatite, using direct current (DC) plasma, to enhance the prolifera...

There is an increasing demand for polyimide-based conductive composite materials with excellent mechanical properties and good thermostability for engineering and biomedical applications. A strategy has been proposed to produce composites based on polyimide matrices of various rigidities filled with graphene particles. The results of dynamic mechan...

This study investigates the correlation between the molecular weight of semicrystalline polyimide and the properties of injection moldings based on it. It was found that the degree of crystallinity can be increased by annealing of molding. The molecular weight of polyimide materials directly influences their glass transition temperature. An increas...

Polyimides (PIs) are materials that are resistant to high temperatures and crucial for the manufacturing of films, fibers, coatings, and 3D-printed items. PIs are widely used as electrically insulating materials in electronics and electrical engineering. This study investigated how the chemical structure (i.e., choice of initial monomers), the synt...

This work investigates the electrophysical properties of thermoplastic and thermosetting polyimides (PI): electrical conductivity, dielectric strength, dynamic mechanical characteristics. In order to increase the dielectric strength, composite materials based on polyimide matrices are synthesized. The glass transition temperatures Tg for PI are det...

The article presents data on the method of obtaining porous nonwoven polyimide fabrics (membranes), their deformation and strength characteristics, heat resistance, and surface properties. The membranes are produced as a result of a multistep processing of copoly(urethane‐imides) prepolymers that includes the synthesis of copoly(urethane‐amiс acids...

The paper describes changes in the structure, morphology, mechanical and thermal properties of porous film samples of poly(4,4′-oxidiphenylene)pyromellitimide prepared as a result of selective destruction of urethane blocks in copolymers composed of pyromellitimide blocks and polyurethane blocks. The initial samples of the new composition of statis...

New composite materials were obtained on the basis of segmental copoly(urethane-imides) and carbon particles of various types: amorphous carbon (carbon black), carbon nanofibers, and graphene. The matrix copoly(urethane-imides) were prepared by known procedures starting from toluylene 2,4-diisocyanate-terminated poly(propylene glycol), pyromellitic...

В условиях управляемой термодеструкции уретановых блоков в сополи(уретан-имиде), содержащем уретановые и имидные звенья в мольном соотношении 1:10 и допированном графеном (1.0 мас% от массы полимера), синтезированы пленки поли(оксидифенилен)пиромеллитимида с развитой пористой поверхностью. Полученные композитные пленки использованы в качестве субст...

The paper investigates the properties of polymer composite films comprised of chitosan and 1% hydroxyapatite nanoparticles following treatment with a plasma jet, using argon as the working gas. Hydroxyapatite is typically added to chitosan to enhance its mechanical properties. The study found that plasma jet treatment increases both the mechanical...

New foaming prepolymer compositions based on 4,4′‐oxydiphthalic anhydride, 4,4′‐diaminodiphenyl ether, 1,6‐hexamethylenediamine (HMDA), and a surfactant were synthesized. Polyimide (PI) foams containing from 0 to 40 mol% HMDA were prepared. The possibility of controlling the pore sizes in a foam material by selecting different fractions (250–400 μm...

Three-dimensional (3D) bioprinting opens up many possibilities for tissue engineering, thanks to its ability to create a three-dimensional environment for cells like an extracellular matrix. However, the use of natural polymers such as silk fibroin in 3D bioprinting faces obstacles such as having a limited printability due to the low viscosity of s...

The selective destruction of urethane and imide units in a copoly(urethane-imide) obtained on the basis of pyromellitic anhydride, 4,4′-oxydianiline, toluene-2,4-diisocyanate, polycaprolactone and containing an increased proportion of imide units was investigated. A sequential destruction was carried out, including preliminary thermolysis of the sa...

Textile materials are widely used in various felds of industry and life. Modifcation of the properties of textiles can lead to an expansion of the possibilities of using a particular material. In this work, the cotton fabric was modifed in inductively coupled plasma in an octafuorocyclobutane gas C4F8 environment. It turned out that such treatment...

The effects of isometric annealing on crystalline structure and dielectric behavior of polyvinylidene fluoride (PVDF) films extruded at variation of the melt draw ratios (λ) were studied. It is shown by the investigations that an increase in λ leads to a continuous growth in crystallinity and orientation factor in extruded films. It is observed tha...

This study focuses on charge relaxation process in a new composite material based on polylactide (PLA) and montmorillonite (MMT), which was used as a filler. The samples with different mass concentration of MMT were charged in a corona discharge and studied using the compensation method with a vibrating electrode. Time dependences of the electret p...

Inks for 3D printing were prepared by dispersing bacterial cellulose nanofibers (CNF) functionalized with methacrylate groups in a polymerizable deep eutectic solvent (DES) based on choline chloride and acrylic acid with water as a cosolvent. After 3D printing and UV-curing, the double-network composite gel consisting of chemically and physically c...

Surface modification of polylactide films was performed using a dielectric barrier discharge (DBD) with the aim of increasing proliferative activity of human fibroblasts on these films. It has been shown that during the plasma treatment of the polylactide film, nonlinear processes occur depending on the processing time. The effect of the dielectric...

New tubular conduits have been developed for the regeneration of peripheral nerves and the repair of defects that are larger than 3 cm. The conduits consist of a combination of poly(L-lactide) nanofibers and chitosan composite fibers with chitin nanofibrils. In vitro studies were conducted to assess the biocompatibility of the conduits using human...

For the first time, a study of the influence of the molecular weight of the thermoplastic partially crystalline polyimide R-BAPB on the thermophysical and mechanical properties of carbon plastics was presented. The molecular weight of polyimide was determined using the method of light scattering and the study of the intrinsic viscosity of polyamic...

Composite threads based on polylactide (PLA) containing up to 20 wt% carbon nanofibers (CNF) were produced using melt technology. The formation of a percolation cluster was studied in composite filaments with various morphologies (non‐oriented, subjected to isothermal crystallization, and oriented by six times). By adding 20 wt% CNF, a specific res...

This study focused on a potential application of electrically conductive, biocompatible, bioresorbable fibers for tubular conduits aimed at the regeneration of peripheral nerves. The conducting, mechanical, and biological properties of composite fibers based on chitosan and single-walled carbon nanotubes were investigated in this paper. It was show...

The electret properties of composites based on polylactide (PLA) filled with montmorillonite (MML) have been studied. With an increase of filler content, the stability of the electret state increases, as well as the charge and amplitudes of the TSD currents. The current spectra are analyzed based on the concept of a superposition of discrete elemen...

Foaming prepolymer compositions based on 4,4'-diphenyloxytetracarboxylic acid dianhydride ethyl ester, 4,4'-diaminodiphenyl ether, 1,6-hexamethylenediamine and surfactant are synthesized. The structure of the synthesized compounds is confirmed by the IR spectroscopy; the data of scanning electron microscopy of samples of the formed foam materials a...

This work focuses on DBD (dielectric barrier discharge) surface modification of polylactide (PLA) films. The film samples were treated in a cold plasma in order to optimize their biological properties and interaction with human skin fibroblasts. Optimal film processing modes for the increased proliferative activity of cells have been found.

В данной работе исследованы электрофизические свойства новых композиционных диэлек­триков на основе полилактида. С целью улучшения электретных свойств в полилактид были до­бавлены наполнители: гидроксиапатит, повиаргол, углеродные нановолокна. В ходе выполнения работы получены данные о скорости спада электретной разности потенциалов на образцах, об...

Surface modification of films of the laboratory R‐BAPB polyimide based on 1,3‐bis(3,3′,4,4′‐dicarboxyphenoxy)benzene (dianhydride R) and 4,4′‐bis(4‐aminophenoxy)biphenyl (diamine BAPB) was performed using a dielectric barrier discharge (DBD) with the aim of increasing proliferative activity of human fibroblasts on these films. The optimal duration...

Biocompatible electrically conducting chitosan-based films filled with single-wall carbon nanotubes were obtained. Atomic force microscopic studies of the free surface topography revealed a change in the morphology of chitosan films filled with single-wall carbon nanotubes. Introducing 0.5 wt.% of single-wall carbon nanotubes into chitosan results...

This work focuses on new chitosan-based composite materials. In order to improve chitosan conductivity, single-wall carbon nanotubes (SWCNT) were added as a filler. The structure of the composites was studied using a scanning electron microscope. It is shown that the addition of SWNCT filler leads to chitosan structure ordering. The increase in SWC...

In this work, an electrically conductive composite based on thermoplastic polyimide and graphene was obtained and used as a bioelectrode for electrical stimulation of human dermal fibroblasts. The values of the electrical conductivity of the obtained composite films varied from 10⁻¹⁵ to 10² S/m with increasing graphene content (from 0 to 5.0 wt.%)....

The experimentally tested schemes are presented for the synthesis of copoly(urethaneimides) and related composites with complicated molecular structures: multiblock (segmented) copolymers with enhanced and lowered relative contents of thermodynamically incompatible rigid imide and flexible urethane (polyether and polyester) blocks, composites of co...

Multiblock (segment) shape memory poly(urethane-imide) copolymers (PUIC) were studied by thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The title polymers were synthesized from 2,4-toluene diisocyanate, aliphatic polyesters/polyethers including poly[di(ethylene glycol) adipate] diol, polypropylene gl...

Using the methods of X-ray diffraction and scanning electron microscopy, the structure of composite films based on chitosan and single-wall carbon tubes has been studied. It is shown that the introduction of carbon nanotubes leads to the ordering of the chitosan structure. Increase in concentration of nanotubes (from 0 to 3%) causes rise in the val...

Using the methods of X-ray diffraction and scanning electronmicroscopy, the structure of composite films based on chitosan andsingle-wall carbon tubes has been studied. It is shown that theintroduction of carbon nanotubes leads to the ordering of the chitosanstructure. Increase in concentration of nanotubes (from 0 to 3%) causesrise in the value of...

Conducting composite based on biocompatible chitosan and single wall carbon nanotubes was used as a matrix for electrical stimulation of human fibroblasts. Parameters of ionic and electronic currents passing through the matrix upon applying cyclic potentials (±100 mV) were studied; the scaffold demonstrated high stability in the course of prolonged...

The work focuses on the study of the charge relaxation kinetics in composite materials based on polyethylene. Time dependences of the electretic potential differences for samples with different mass values of the filler, as well as dependences of conductivity from the mass percentage of the filler, were achieved. The conductivity curves were analyz...

In this work, the surface of polyimide films of PMDA-ODA was modified using a barrier discharge in order to optimize their biological properties when interacting with a culture of human dermal fibroblasts. The optimal modes of processing films in a gas discharge, which allows to increase the proliferative activity of cells, are found.

The relaxation of homocharge of polyimide films with different rigidity of macromolecules was studied by thermal activation spectroscopy. We used laboratory films R-BAPB, PMDA-ODA and DP-OTD. Using the method of computer simulation, complex spectra of thermally stimulated depolarization (TSD) currents are decomposed into individual elementary peaks...

Using a twin-screw microextruder, fibers based on polylactide and vapor grown carbon nanofibers (VGCF) with orientational stretching by 4 and 6 times were obtained. It was shown that VGCF doesn't influence on thermal properties of composite fibers based on PLA. Also, evenly dispersion of VGCF in PLA matrix was observed using by SEM. The electricall...

The paper is devoted to the study of influence of chitin nanofibrils on the structure, surface morphology, mechanical properties, and electrical conductivity of chitosan-based composite films intended for use in biomedical technologies. It was demonstrated that the optimal concentration of chitin nanofibrils in the composite film is 5 wt.%. For the...

Conducting composite based on biocompatible chitosan and single wall carbon nanotubes was used as a matrix for electrical stimulation of human fibroblasts. Parameters of ionic and electronic currents passing through the matrix upon applying cyclic potentials (±100 mV) were studied; the scaffold demonstrated high stability in the course of prolonged...

The results of the investigation electrical characteristics of thermoplastic polyimide R-BAPB films are presented. The absorption charging currents Ich(t) of R-BAPB were measured experimentally in temperature range of 25-150 °C for 3 hours. The experimental data were analyzed correspond to Voigt equivalent circuits. Main dielectrical characteristic...

The process of near-electrode polarization in a polyvinylidene fluoride (PVDF) film was studied using reverse currents Irev(t). It was proven that the maxima on the Irev(t) curves are characteristic of near-electrode polarization. The dependences of the reversal currents on time were analyzed based on various representations. The mobilities of the...

In the work composite films based on chitosan and single-walled carbon nanotubes (0.01%, 0.1%, 0.5% and 1%) were obtained. The electrical and mechanical properties of the composite films were measured. It was shown that a film with 1% SWCNT has sufficient electrical conductivity and optimal mechanical properties for the bioactivity of a culture of...

This work is devoted to the study of electrical relaxation processes of thermoplastic R-BAPB polyimide based on 1,3-bis(3,3',4,4'-dicarboxyphenoxy)benzene (dianhydride R) and 4,4'-bis(4-aminophenoxy)biphenyl (diamine BAPB). The films were produced by casting onto a glass substrate and by extrusion melting. The mechanisms of charge accumulation and...

Using a twin-screw microextruder, fibers based on polylactide and carbon nanofibers (CNFs) were obtained with 4-and 6-fold orientational stretching. The electroconductive and deformation-strength properties of composite fibers were investigated depending on the concentration of the filler and orientational stretch ratio of the polymer. It is shown...

The intensity distributions of scattered coherent radiation are studied using polyethylene films filled with single-walled carbon nanotubes. The use of a spectral-correlation method for analyzing the intensity distributions over various wavelengths make it possible to establish the relationship between certain parameters of the cross-correlation fu...

This paper discusses the electrical conductivity of chitosan-based film matrices, as well as optimization of these properties by adding chitin nanofibrils. It has been shown that the filler addition increase the conductivity of the composite material. By changing the concentration of chitin nanofibrils, it is possible to obtain matrices with differ...

The molecular mobility of poly(4,4'-bis(4-aminophenoxy)biphenyl)imido-1,3-bis(3,3'-4,4'-dicarboxyphenoxy) benzene) films is studied by the thermally stimulated depolarization current (TSDC) technique and dielectric spectroscopy. The existence of two dipolar polarization relaxation regions (β and α) related to the local mobility in the glassy state...

The effect of the degree of crystallinity on relaxation processes in poly((4,4'-bis(4-aminophenoxy) biphenyl)imido-1,3-bis(3,3'-4,4'-dicarboxyphenoxy)benzene) films is studied by thermoactivation spectroscopy and dynamic mechanical analysis. Using thermoactivation spectroscopy, it shown that the β transition is caused by the dipole-group relaxation...

The charge relaxation processes in the films based on R-BAPB polyimide with different degree of crystallinity have been studied. The supramolecular structure effect on the charge relaxation processes in the films under elevated humidity conditions was revealed. The obtained experimental data was analyzed in the context of the present-day knowledge...

The method of thermoactivation spectroscopy is used to study effect of the degree of crystallinity on the mechanisms of homocharge relaxation in poly((4,4'-bis(4-aminophenoxy)biphenyl)imido-1,3- bis(3,3'-4,4'-dicarboxyphenoxy)benzene films. Two regions of charge relaxation are found. At a temperature of 177°С (450 K), there is a maximum of the ther...

The aim of this work is the experimental and theoret-ical study of charge relaxation processes in the films of polyimide coated on both sides with lacquer PTFE (PMF-2), charged in a co-rona discharge at negative polarity in ambient conditions. The the-oretical analysis is based on the model of quasi-continuous distri-bution of traps with respect to...

The aim of this work consists in pursuit of electret structure with excess humidity and high thermostability. The charge relaxation mechanism in polyimide and modified polyimide films is established. It is shown that the layers of polytetrafluoroethylene on surface of polyimide films lead to essential increasing of electret state stability at eleva...

The charge relaxation processes in the films based on polyimide and polytetrafluoroethylene (the latter serves as a coating) have been studied. The coating effect on the charge relaxation processes in the films under high humidity conditions was revealed. The obtained experimental data was analyzed in the context of the present-day knowledge of the...