The morphology and filtration properties of the porous polyimide materials prepared as a result of processing of prepolymers: copoly(urethane-imides) (CPUI) of varied chemical composition. The destruction of polyether units linked with polyimide units via isocyanate groups in the initial copolymers and formation of a porous material with the poly(urethane-imide) structure occur during calendering and controlled annealing of microfibrous fabrics. In this case, shrinkage of the fabrics and a decrease in the pore size were observed. Polycaprolactone, 2,4-toluylene diisocyanate, 4,4′-oxydianiline, pyromellic dianhydride, and 3,3′,4,4′-oxydiphthalic anhydride were used in CPUI synthesis. The CPUI samples were studied by thermogravimetric analysis and scanning electron microscopy. Their deformation and strength properties were determined. The influence of both CPUI chemical structure and calendering and subsequent thermal annealing modes on the morphological structure and filtration characteristics of the final materials was shown. The final porous materials derived from the CPUI-III and CPUI-IV samples demonstrate optimal filtration properties: the permeability values for pure DMF are 281.6 and 278.0 kg (m2 h atm)−1, respectively, while for a dye solution in DMF they are 93.9 and 111.9 kg (m2 h atm)−1, and the phthalocyanine retention coefficient is 98

A bioresorbable tubular graft with a diameter less than 5 mm intended for reconstruction of blood vessels was developed; the inner layer of the graft consisted of poly(L-lactide) nanofibers, and the outer layer consisted of poly(ε-caprolactone) nanofibers. The in vivo experiments on reconstruction of the rat abdominal aorta showed that the implants had good biocompatibility and high thromboresistance in the absence of cytotoxicity. The morphological studies revealed two processes occurring simultaneously in the implant: bioresorption of polymeric fibers and formation of blood vessel tissues. It was established that after 24 months of observation, a vessel fragment was formed at the site of the polymeric implant: its neointima consisted of epithelial and subepithelial layers, and neomedia included connective tissue cells and fibers, as well as the remnants of fragmented poly(L-lactide) and poly(ε-caprolactone) nanofibers. The outer layer of the graft (neoadventitia) consisted of a network of collagen fibers, numerous vasa vasorum, isolated multinucleated foreign body giant cells and macrophages.

Mechanochemical treatment of air-dried mixtures composed of polyvinyl alcohol (or polyacrylamide) and food-grade gelatin at various mass ratios is carried out in a vibrating cup sample grinder for 1, 3, and 5 min. As a result, gelatin/polyvinyl alcohol and gelatin/polyacrylamide composites are obtained. The structure, morphology, and optical and rheological properties are studied using infrared spectroscopy, scanning electron and optical microscopy, gravimetry, viscometry, and turbidity spectroscopy. It is found that mechanical activation promotes noncovalent interactions between components and the formation of a new system of hydrogen bonds, leading to changes in the microstructure of powders and in the viscosity of aqueous solutions. It is shown that mechanochemical activation of gelatin with polyacrylamide and polyvinyl alcohol is a promising method for producing film composites with a wide range of applications, including the pharmaceutical and medical fields.

Materials based on uniaxially oriented poly(L-lactide) (PLA) nanofibers are obtained using the electrospinning method. A study of the structure, carried out using scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry, shows that the nanofibers are characterized by an amorphous structure with the orientation of macromolecules relative to the axis of the nanofiber, i.e., a liquid-crystalline-type structure. The strength of such nanofibers is 78.3 MPa, the modulus of elasticity is 11.25 MPa, and the elongation at break is 142

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-ami & scy; acids) of a given chemical composition, the molding of nonwoven fabrics (mats) by electrodeposition of copoly(urethane-amic acids), the compaction of the volumetric structure of electrodeposited nonwoven fabrics by calendering on hot rollers, the thermal cyclization (imidization) of amic acid units of copolymers during calendering to form imides, and the controlled selective thermal destruction of the urethane groups in the copolymers conditioning the transition from poly(urethane-imides) to polyimides, which is accompanied by the formation of pores in nonwoven polyimide fabrics, resulting in porous polyimide webs with specific properties. In the synthesis of the polymers studied, polycaprolactone diol, 2,4-toluene diisocyanate, 4,4 '-oxydianiline, pyromellitic dianhydride, and 3,3 ',4,4 '-oxydiphthalic anhydride were used. The polymers were characterized using X-ray, 1H NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and scanning electron spectroscopy. The deformation and strength properties of the nonwoven polyimide fabrics were also determined. Chemical composition of the synthesized polymer systems and the conditions for creating porous polyimide nonwoven fabrics influence the physical properties of the resulting fabrics. Porous polyimide nonwoven fabrics hold promise for the development of advanced filtration materials with enhanced strength, heat resistance, and resistance to aggressive amide solvents, which could be used in the pharmaceutical and biotechnology industries. The nonwoven fabrics are based on copoly(urethane imides) in terms of dimethylformamide (DMF) permeability and phthalocyanine rejection with a diameter of 240 nm. The DMF permeability was 280 kg/m2 h bar, the phthalocyanine rejection was 98%.Highlights Nonwoven poly(urethane-amic acid) materials were obtained by electrodeposition. Nonwovens were rolled at high temperatures and pressure. The materials were compacted and acquired the structure of poly(urethane-imides). Porous polyimide materials were obtained by annealing poly(urethane-imides). The obtained materials have the properties of ultrafiltration membranes.

Porous crosslinked polyelectrolyte microspheres 1–5 μm in diameter have been synthesized on the basis of either p-styrene sulfonate used as a functional monomer or a mixture of p-styrene sulfonate and vinyl acetate. The content of sulfonate groups in the obtained polyelectrolyte microspheres is higher than 2 mmol/g. It has been shown that the incorporation of the hydrophobic comonomer significantly increases the swelling degree of the polyelectrolyte microspheres. The adsorption value of model compounds (fuchsine and methylene blue) has been found to significantly exceed the concentration of sulfonate groups. The morphology and structure of the surface layer of polyelectrolyte microspheres have been studied by optical and scanning electron microscopy and FTIR spectroscopy, while their specific surface area has been determined by the BET method.

Tubular conduits have been developed for regeneration of peripheral nerves and repair of defects with a diastasis of more than 3 cm. The optimal conduit design included a tube based on poly(L-lactide) nanofibers and a filler in the form of composite chitosan fibers containing chitin nanofibrils. A study of motor coordination disorders was conducted in vivo using an assessment of the functional index of the sciatic nerve. It has been shown that the presence of chitosan monofilaments and chitosan composite fibers containing chitin nanofibrils in the conduit structure increased the rate of regeneration of the sciatic nerve; its functional index was 76–83. The degree of restoration of nerve conduction determined by measuring the amplitude of the M-response was 46

An express method of solvent-free dry mechanochemistry using fine grinding in air for 3 and 6 minutes in a mill (0.94 kW; 26 000 rpm) is employed to targetedly change the structure of kaolin and increase its sorption capacity. During the same process, kaolin is modified together with hydrolytic lignin to hydrophobize its surface and improve its sorption properties. The influence of the mechanical activation on the structure and properties of kaolin, hydrolytic lignin, and their composites with different component ratios is studied using electronic microscopy, X-ray diffraction, infrared spectroscopy, low-temperature nitrogen adsorption, and UV absorption spectroscopy. The dense structure of kaolinite remains preserved, hydrogen bonds in hydrolytic lignin are ruptured, and the number of carbonyl groups increases, while fragments of the natural polymer are grafted to kaolinite. It has been found that an agglomeration–aggregative microstructure is formed in the composites. Kaolin and the kaolin–hydrolytic lignin composite (10 : 1, weight/weight) treated at a mechanical energy dose of 0.83 kJ g–1 undergo significant structural changes and exhibit rather high sorption characteristics. The Brunauer−Emmett−Teller specific surface area of these sorbents is ∼16 m2 g–1, while their adsorption capacities for bovine serum albumin are 83.63 and 44.10 mg g–1, respectively. Thus, the dry mechanical activation in air under “mild” conditions makes it possible to increase the sorption of bovine serum albumin on kaolin by 104

a method for calculating the size distribution of nanocrystalline elements of the polymer structure is proposed. The longitudinal size distribution (thickness) of ultrahigh molecular weight polyethylene lamellae was calculated from calorimetric data. The results of calculating the maximum values of the distribution are consistent with the known data obtained by other methods.

Monodisperse polymer particles of the core–shell type were produced using sequential emulsion and seed emulsion polymerization methods. The structure of the surface layer of the particles was studied using scanning electron microscopy. It has been established that sequential emulsion polymerization makes it possible to obtain particles with the lowest dispersity values of their diameter. The introduction of methyl methacrylate both at the stage of core synthesis and during the formation of the shell leads to the formation of spherical particles with a smooth surface layer. Based on such particles, films with pronounced properties of photonic crystals were obtained, and their Bragg reflection spectra in polarized light were studied.

Методами последовательной эмульсионной и затравочной эмульсионной полимеризации изготовлены монодисперсные полимерные частицы типа ядро‒оболочка. Структура поверхностного слоя частиц изучена с помощью растровой электронной микроскопии. Установлено, что последовательная эмульсионная полимеризация позволяет получать частицы с наименьшими значениями дисперсии их диаметра. Введение метилметакрилата как на стадии синтеза ядер, так и в процессе формирования оболочки приводит к формированию сферических частиц с гладким поверхностным слоем. На основе таких частиц получены пленки с ярко выраженными свойствами фотонных кристаллов и исследованы их спектры брэгговского отражения в поляризованном свете.

A set of ionic cryogels based on the biocompatible zwitterionic polyelectrolyte N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine and a second comonomer of a different nature (from the class of acrylates, acetates or sulfonic acids) is successfully synthesized. The variation of the nature of the comonomer used allows a material to be obtained with controlled pore sizes and hierarchical porosity as proved by SEM, optical microscopy and N2 adsorption-desorption experiments. The compositions of cryogels with good adhesive properties to the electrode, as well as effective ion exchange during an electrochemical reaction inside the cryogels, which is shown by reversible copper recharge processes after doping a cryogel with copper ions, are determined. Thus, cryogels that meet the primary requirements for a material for use as polymer electrolytes for batteries are synthesized and characterized. (c) 2024 Society of Chemical Industry.

Submicron-sized core/shell particles were prepared by polymerizing a mixture of methyl methacrylate and butyl acrylate in the presence of seeds of monodisperse polystyrene or its copolymer with methyl methacrylate. The influence of core/shell particle preparation conditions (method of shell formation, core composition, reaction temperature, introduction of surfactants, method of introducing monomers) on kinetics of the process, shape and surface morphology of the resulting particles is revealed. Depending on the abovementioned parameters, particles of various morphologies can be obtained, including both ones with a smooth surface layer and with a heterogeneous “golf ball-like” structure, while the presence of dents, as well as their size and the number can also be controlled by the synthesis conditions. The result of polymerization, that is, the morphology of core/shell particles and the formation of secondary particles, is established to be determined primarily by thermodynamic factors that take into account the distribution of shell-forming monomers in an equilibrium state.

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 mechanical analysis demonstrate that the values of glass transition temperature and elastic modulus of these composites increase (from 3.1 GPa to 9.6 GPa) with increasing rigidity of the PI matrix. An increase in the PI rigidity also leads to a decrease in volume conductivity of samples (from 10–4 to 5 × 10–7 S/m), while their surface conductivity increases (from 0.04 S/m to 2 S/m). Apparently, this is due to expulsion of graphene into the near-surface area of the composite film, which is confirmed by independent methods (X-ray photoelectron spectroscopy and IR spectroscopy). The macromolecules of rigid-chain polyimide demonstrate planar orientation, which facilitates the appearance of strong π–π-interactions between monomer units of polymer chains and prevents uniform distribution of graphene particles within the volume of this polyimide matrix.

New method of emulsion synthesis of Nafion®-type copolymer composition by using nanodiamond platform has been proposed and implemented. Produced polymeric coagulate saturated with diamonds (4.1 % wt.) possessed increased ionic capacity of the copolymer comparative to the analogue without diamonds. SEM patterns for coagulate membranes showed labyrinthine structures with diamonds integrated into copolymer without any segregation. This structuring provided necessary elastic and strength properties of new type membranes for hydrogen fuel cells. In new membranes synchrotron experiments exhibited a network of ionic channels which ensured a proton conductivity by one order of magnitude higher than that for the analogue produced of premade components.

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 such solutions. This study addresses these gaps by developing highly viscous, stable, and biocompatible silk fibroin-based inks. The addition of 2% carboxymethyl cellulose sodium and 1% sodium alginate to an aqueous solution containing 2.5 to 5% silk fibroin significantly improves the printability, stability, and mechanical properties of the printed scaffolds. It has been demonstrated that the more silk fibroin there is in bioinks, the higher their printability. To stabilize silk fibroin scaffolds in an aqueous environment, the printed structures must be treated with methanol or ethanol, ensuring the transition from the silk fibroin’s amorphous phase to beta sheets. The developed bioinks that are based on silk fibroin, alginate, and carboxymethyl cellulose demonstrate an ease of printing and a high printing quality, and have a sufficiently good biocompatibility with respect to mesenchymal stromal cells. The printed scaffolds have satisfactory mechanical characteristics. The resulting 3D-printing bioink composition can be used to create tissue-like structures.