Novel aromatic copoly(amide-imides) have been synthesized using 2-(4-carboxyphenyl)-1,3-dioxoisoindoline-5-carboxylic acid and two diamines, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane and metaphenylenediamine, taken at molar ratios of 7 : 3, 1 : 1, and 3 : 7. The structure, thermal, mechanical, morphological, and transport properties of copoly(amide-imide) nonporous membranes have been studied in comparison with similar copoly(amide-imides) containing carboxyl-containing fragments. It has been shown that films of poly(amide-imides) and copoly(amide-imides) with carboxyl groups –COOH in the diamine fragment exhibit higher permeability compared to similar polymers containing metaphenylenediamine fragments in macrochains and are characterized by more pronounced hydrophilicity. This effect is determined by the occurrence of intra- and intermolecular interactions, with the latter predominating for the copolymers containing carboxyl groups, and their virtual absence in copoly(amide-imides) with metaphenylenediamine fragments, as confirmed by thermal analysis and molecular hydrodynamics.
The results of the rheological study of aqueous solutions of poly(N-vinylpyrrolidone) in the shear flow mode at different concentrations and temperatures in a magnetic field and in its absence are presented. The influence of a magnetic field on the enthalpy of activation of a viscous flow process ΔHvisc was studied for the first time; it value was calculated according to the Frenkel–Eyring equation based on data on the temperature dependence of the viscosity of solutions. It was found that in a magnetic field the value of ΔHvisc is higher than that outside the field. This is due to the additional orientation of diamagnetic macromolecules and the strengthening of interchain interaction, which promotes the association of macromolecules. This is confirmed by the increase in viscosity. A nonmonotonic increase in ΔHvisc is observed with increasing concentration of poly(N-vinylpyrrolidone) in solutions.
RAFT polymerization was applied for the synthesis of poly(4-vinylpyridine) and copolymers of 4‑vinylpyridine, containing 5 or 10 mol
Chitosan Portunus trituberculatus (Eschscholtz, 1823) with a molecular mass of 780 kDa and a deacetylation degree of 84
In this study, the optimal degree of polymerization of polyvinyl alcohol (PVA) and appropriate carbonate content necessary to enhance the separation performance of a CO2 separation membrane were determined. The membrane was composed of a composite polymer of PVA, which is known for its gas barrier properties, and sodium polyacrylate (PAANa), which acts as a water-absorbing agent. The PVA/PAANa membranes exhibited pressure resistance even without a cross-linking agent. To further improve the separation performance, membranes were prepared using PVA with four different degrees of polymerization (400–600, 1500–1800, 2000, and 3100–3900), and their separation capabilities were evaluated. Additionally, the optimal amount of caesium carbonate that enhances CO2 permeance was determined. It was found that separation membranes made from PVA with a degree of polymerization of 1500-2000 exhibited higher separation performance. In particular, separation membranes fabricated with PVA with a degree of polymerization of 2000 showed the best separation performance. As a result, a high-performance CO2 separation membrane was successfully developed, achieving a CO2 separation performance of approximately 3.2E-10 (m3(STP)/(m2 s Pa)) and a CO2/He selectivity 700.
Molecular dynamics models of five polyimides (PIs) based on commercially available dianhydrides PMDA, BTDA, ODPA, 6FDA, and BPADA and 1,4-bis-[2′-trifluoromethyl 4′-(4″-aminophenyl)phenoxy] 2,5-di-t-butylbenzene (FMTBDA) were constructed. Intramolecular mobility of these polyimides was investigated via analysis of the distribution of torsion angles values, torsion angle fluctuation amplitude and rotational mobility of aromatic rings. It was demonstrated that two phenyl rings in diamine connected by С–С bond, are forming quite rigid fragments with predominantly uniplanar position of the rings, while two phenyl rings connected by C–N bonds (between diamine and di-anhydride) allow greater variety of conformations. Nevertheless, the imide cycle of the dianhydride fragment conjugated to the diphenyl fragment of diamine tend to form a plane. The mobility of the polymers being investigated ascends in the order: BPADA-FMTBDA < 6FDA-FMTBDA ≅ ODPA-FMTBDA ≅ BTDA-FMTBDA < PMDA-FMTBDA. This trend agrees well enough with previously obtained estimates for their fractional free volume (FFV). Trajectories for the pairs of dihedral angles were estimated, showing that these mainly contain the jumps between the minima of the rotation energy diagrams. Lower rotational mobility of the di-tert-butylbenzene fragment in all the polymers was observed, which is due to the moment of inertia of the bulky tert-butyl groups and due to the restriction of the mobility in a dense amorphous polymer matrix because of these groups.
The crystallization behavior of semicrystalline polymers is crucial for tailoring material properties for industrial and scientific applications, particularly when traditional methods such as differential scanning calorimetry (DSC) are precluded by cost, inaccessibility, or sample size. We investigated the potential of digitally extracted pixel intensity using Polarized Optical Microscopy (POM) as a quantitative substitute for DSC for assessing polymer melting and crystallization behaviors. Using isotactic polystyrene (iPS) as a model polymer, rigorous calibration established a correlation between illuminance and digitally extracted pixel intensity (DPI). Calibration enables real-time in situ monitoring of crystallization and melting processes. Comparative analyses of melting endotherms and crystallization exotherms obtained using DPI and DSC demonstrated a strong correlation, validating DPI as an effective thermal analysis method. This study also highlights the non-destructive nature of DPI, its morphological visualization capabilities, and its potential for integration with automated digital imaging and machine-learning techniques. These findings offer a promising pathway to accessible, cost-effective, and real-time polymer characterization, which transcends limitations of conventional calorimetry. When rigorously calibrated against illuminance, DPI can track melting and crystallization trends that correlate with DSC heat flow features. However, DPI does not measure heat flow and should be interpreted as an optical surrogate, not a calorimetric equivalent.
This study investigated pore growth during stretching of polymerization-filled composites based on Al2O3 particles coated with ultra-high-molecular-weight PE, HDPE, or a dual-layer ultra-high-molecular-weight PE/HDPE coating. The particles were spherical in shape with an average diameter of 20 μm. When the composite was stretched, the particles exfoliated, creating pores. During stretching, the spherical pores were elongated, first becoming elliptical and then conical. The sharp angles of the rhomboid pores are due to the plastic flow of the polymer, not its degradation. Pore volume increases linearly with the material extension ratio. This increase in pore volume is due to the presence of rigid particles within the pores, which limit the lateral contraction of the composite. Bands representing transverse interactions between the particles and the polymer are visible in the equatorial region of the pores. Presumably, polymer elongation is greatest in these microregions and the polymer degradation process begins in them. It has been hypothesized that at a temperature of 190°C, the tensile stresses generated during composite pressing do not relax in the ultra-high-molecular-weight PE melt. This is explained by a molecular entanglement network.
Expressions have been obtained to trace the time (t) dependence on the concentration of radicals ([R]) created by a short radiation pulse, taking into account the chain-length dependence of propagation and termination rate coefficients. These expressions have been used to test the accuracy of determining the parameters of the composite model of the termination rate coefficient by single pulse-pulsed laser polymerization-electron paramagnetic resonance (SP-PLP-EPR) method using in silico modeling. Testing has shown that to find the transition chain length Lf of the composite model, it is correct to search for the inflection point of the dependence of log( ρ/[R] - 1) on log(t), rather than determining the break point of this dependence. Also, due to the influence of the chain-length dependence of the propagation constant for short radicals, the parameters of the composite model of chain termination are determined with a significant systematic error.
Magnetic microparticles with silicon shells of varying thickness have been obtained by modifying the surface of carbonyl iron. The structure and magnetic properties of the particles have been studied using scanning electron microscopy and vibrational magnetometry. The original and modified particles have been used as fillers to create magnetoactive elastomers based on polydimethylsiloxane. The concentration of magnetic particles in the magnetoactive elastomers varied from 40 to 80 wt
Unwanted icing on solid surfaces presents a critical challenge in a wide range of technological applications due to its detrimental effects on functional stability, energy efficiency, and overall system reliability. To address this phenomenon, multiple strategies have been explored, including the development of icephobic surface coatings, mechanical deicing techniques, thermal deicing systems, deployment of chemical deicing agents, and other advanced mitigation methods. In this study, novel nano-magnetically functionalized polyvinylidene fluoride (PVDF)/Fe3O4 fibrous films were engineered, exhibiting enhanced potential for use as icephobic materials. The electrospinning process was employed to fabricate highly aligned ferromagnetic nanofibers, with the incorporation of magnetite (Fe3O4) nanoparticles into the PVDF matrix leading to a significant increase in the electroactive β-phase fraction. The application of a directional magnetic field during electrospinning facilitated the production of uniformly oriented nanofiber architectures, enabling comprehensive evaluation of their morphological characteristics and anti-icing performance. Advanced characterization techniques, including wettability and icephobicity assessments, infrared spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), were employed. The findings demonstrate that the precisely oriented nano-fibrous magnetic coatings exhibit superior icephobic performance, underscoring their suitability for next-generation anti-icing and deicing applications in critical technological systems.
Changes in the structure and mechanical properties of poly(ε-caprolactone) films and fibers during their exposure to iodine vapors have been studied. The limit content of iodine in polymer samples has been reached in 15–18 h, being about 5
The effect of molecular weight characteristics of high-density polyethylenes in a wide molecular weight range from ultrahigh to low molecular (polyethylene, close to the brittleness threshold), as well a reactor polymer composite ultrahigh-molecular-weight PE–HDPE, which were synthesized in the presence of a heterogeneous catalyst based on VCl3, on the structural parameters and deformation–strength properties of polyethylene was studied. It was shown that the supramolecular structure parameters and deformation–strength properties of the synthesized polyethylenes correlate with their molecular weight characteristics. Polymers with a MW lower than that of ultrahigh-molecular-weight PE and a reactor polymer blend ultrahigh-molecular-weight PE/HDPE are characterized by bimodal MWDs with a wide Mw/Mn. With decreasing MW, the proportion of a high-molecular-weight fraction decreases. As a result of structural changes, the lamellar long period Lp decreases due to the thinning of the intercrystalline amorphous gap La, which increases the plasticity of the material and decreases its strength.
This report studied the effects of glass fiber (GF) on the mechanical properties of polyamide 6/acrylonitrile butadiene styrene (PA6/ABS) compounds with styrene-ethylene/butylene-styrene (SEBS) as a compatibilizer. Samples with various PA6/ABS/GF compound mixing ratios were prepared by injection molding with 0, 10, 15, 20, 25, and 30 wt
The thermodynamic functions (Gibbs free energy, enthalpy, and entropy of mixing) of TOPAS polycycloolefins (ethylene–norbornene copolymers) in chloroform at 298 K have been determined using microcalorimetry and isothermal equilibrium sorption of solvent vapor. TOPAS-5013 and TOPAS-8007 copolymers with norbornene contents of 46 and 35 mol
The concentration dependences of the viscosity of magnetic fluids Fe–glycerol/water, Fe–ethylcellulose/DMAA, FeOx–polyoxypropylene diol/water, FeOx–ethylcellulose/DMAA, Fe7Ni3–ethylcellulose/DMAA, and Fe7Ni3–glycerol/water have been determined in a magnetic field and outside the field. Applying a magnetic field increases the viscosity of magnetic fluids by 2–4 times, and the concentration dependence of the magnetic-field effect on viscosity can be described by a curve with a maximum.
The incorporation of fillers into polymer matrices is a well-established strategy to enhance mechanical, electrical, and thermal properties. However, filler–matrix compatibility remains a critical factor governing overall performance, often limiting the applicability of promising filler materials. While numerous studies have investigated individual filler systems, a systematic comparative analysis of multiple fillers within an identical polymer matrix remains notably absent. In this work, a comprehensive study is presented on the incorporation of three distinct fillers-clay, multiwalled carbon nanotubes (MWCNTs), and silver nanoparticles (AgNPs) into identical polyaniline-dinonylnaphthalene disulfonic acid (PANI–DNNDSA) gel matrices synthesized under controlled conditions to ensure uniform molecular weight and processing parameters. Each composite was evaluated for its structural, electrical, and mechanical properties to elucidate filler-specific influences and compatibility with the host matrix. The findings contribute valuable insights for both academic research and industrial applications, facilitating informed filler selection for advanced polymer design.
Today, silicon solar modules (SM) represent the most efficient and environmentally friendly renewable energy source. However, as the market for these modules grows, problems with waste and environmental sustainability arise in parallel. Creating SM recycling technologies that fully circulate materials without waste and reuse components is a key issue that must be addressed within corporate social responsibility frameworks for environmental protection. An important step in resin recycling is separating the laminate from poly(ethylene-co-vinyl acetate) (EVA), which is commonly used as an adhesive in resin. Work has been done to reduce EVA using various organic solvents, with parameters such as type of solvent, residence time, and temperature taken into account. It was found that chlorinated hydrocarbons, such as trichloroethylene, chlorobenzene and chloroform, can effectively cause EVA swelling due to their polarity. Aromatic hydrocarbons like toluene and o-xylene provide sufficient interaction with EVA, which makes them more advantageous for industrial applications since they pose less danger than chlorine-containing solvents. Among the solvents tested, toluene turned out to be the best. The second series of tests were carried out using toluene alone, optimizing the separation process of EVA from SM components. The recovered EVA was then studied using various methods, including NMR, UV, Fourier spectroscopy, TGA, and DSC. These studies showed that reconstituted and reference EVAs exhibited similar properties without significant changes in composition. This indicates that reconstituted EVAs can be reused in SM or other applications.
Aqueous microgels with colloidal macromolecular networks attract increasing attention in science and technology due to their unique properties. In this work, poly(N-vinyl-2-pyrrolidone)-based-microgel@SiO2 core-shell particles are prepared via inverse miniemulsion polymerization, and hyperbranched polyethoxysiloxanes of different substitution degrees with non-hydrolysable hexadecyl groups are used as both emulsifier and silica precursor. Thus, an aqueous solution of monomer, cross-linker and initiator is emulsified in a tetradecane solution of the silica precursor using ultrasonication, and polymerization is then carried out via heating. It is shown that the emulsion droplets and subsequently the resulting capsules are smaller when polyethoxysiloxane of a higher hexadecyl substitution degree is employed. The morphology of the composite particles is controlled by the monomer concentration in the aqueous phase. At a low monomer concentration, a yolk-shell structure is formed, where a microgel particle swims in an aqueous phase encapsulated within a silica shell. With the increase of the monomer concentration, the inner aqueous phase becomes fully occupied by a microgel particle with a hollow interior. The hollow structure disappears by raising further the monomer concentration, and the maximal swelling of the microgel particle becomes unreachable due to the lack of water. The microgel@SiO2 capsules are promising carriers of different hydrophilic substances with an extremely slow but triggerable release profile, hence can find numerous applications in cosmetics and biomedicine. The alkyl-polyethoxysiloxane-assisted inverse miniemulsion polymerization is a powerful tool for simultaneous synthesis and microencapsulation.
Following pretreatment, aramid fiber (AF) powder was blended with polyether sulfone (PES) resin powder to fabricate a novel composite material compatible with selective laser sintering (SLS). Tensile and bending specimens of polyether sulfone/aramid fiber (PES/AF) composites were fabricated via selective laser sintering. This study examined the effects of aramid fiber content (0‒4 wt
