Polymer Science, Series A最新文献

The rheological properties of the poly(vinyl alcohol)–water system under the magnetic field and in its absence are studied. It is found that application of the magnetic field leads to changes in the viscosity of the system and the morphology of supramolecular particles formed in solutions. The concentration dependence of the relative viscosity is described by a curve with a maximum.

In this study, PVDF-g-PAA@Cu membranes were prepared by a one-step method in a homogeneous solution irradiated by gamma-ray. The results of Fourier transform infrared spectroscopy (FTIR) and diffraction of x-rays (XRD) showed that the grafting reaction was successful and Cu was stably loaded on the membrane. The microstructure of the membrane was analyzed by SEM. It was found that there were Cu nanoparticles on the inner pore wall of the membrane. The introduction of PAA and Cu effectively reduced the contact angle of the membrane and improved the membrane’s hydrophilicity. Comparing with the bare PVDF membrane, the filtrationand anti-fouling performance of the PVDF-g-PAA@Cu membrane had been largely improved. Moreover, the presence of Cu nanoparticles promoted the bacteriostasis of the membrane.

The use of biocompatible polymeric devices loaded with drugs or bioactive compounds is growing, and it is seen as an excellent alternative to conventional implants or to other clinical therapies. In recent years, the supercritical carbon dioxide process has been developed and received increased attention. In this study, drug-loaded polymer microparticles were prepared using a supercritical solution impregnation process with cefadroxil as the model drug and a nano-hydroxyapatite/chitosan/poly(lactic acid) composite as the drug carrier. The morphology and functional groups of the drug-loaded microparticles were characterized using scanning electron microscopy and Fourier transform infrared analysis. The effects of pressure and temperature on the drug loading and release properties of the prepared microparticles were investigated. The in vitro drug release kinetics of drug-loaded microparticles were studied using five models. These results indicated that the supercritical solution impregnation process did not influence the morphology of the drug-loaded polymer microparticles. The drug was released after more than 50 h and the drug release kinetics showed that the drug release of the drug loaded composite was basically consistent with the Weibull model. This composite is expected to be used as an implant material in the medical field.

Naringenin, an herbal ingredient possesses a diversity of pharmacological action and bioactive functions. In this study, surface molecularly imprinted polymers named as Zeolite imidazolate framework-8 were successfully synthesized and applied in the selective adsorption of naringenin. A series of adsorption experiments evaluated the adsorption properties of polymers. The results showed that the molecularly imprinted polymers had a higher adsorption capacity than non-imprinted polymers. In addition, they have good selectivity for Naringenin compared with other flavonoid compounds, and its imprinting factor for naringenin is as high as 3 in single solutions. The Scatchard plots showed two distinct linear portions, indicating that two kinds of binding sites exist in the molecularly imprinted polymers. After eight cycles, the adsorption capacity of polymers did not decrease significantly in the initial affinity. These results demonstrated that prepared molecularly imprinted polymers could be promising functional materials for the selective adsorption of naringenin.

Mixed 18% solutions of cellulose and PAN terpolymer containing methyl acrylate and methylsulfonate comonomers in N-methylmorpholine-N-oxide have been obtained over the entire range of compositions. All the obtained systems based on cellulose and PAN are biphasic, and the morphological features of the emulsions change from highly dispersed isotropic to fibrillar depending on the phase composition and the intensity of the deformation effect. At high shear stresses that emerge during preparation of the solutions in an extruder, all emulsions are characterized by the same microheterogeneous morphology, which is transformed into fibrillar by deformation. An IR spectroscopic study has established that in the preparation process, specific interactions occur between the functional groups of macromolecules of the cocomponents, leading to the formation of PAN/cellulose associates, which undergo hydrophobic repulsion along the interfaces. It is this process that initiates the fibrillation of the cellulose solution phase in the presence of a PAN solution during deformation. The rheological behavior of mixed solutions over the entire range of concentrations in continuous and dynamic modes at temperatures of 110–130°C is a direct consequence of the phase composition and morphological transformations occurring during deformation. Emulsion compositions characterized by viscoelastic properties that make it possible to successfully form composite fibers have been chosen.

Composite films of methyl cellulose and poly(urethane-imide) are obtained. At the poly(urethane-imide) content in the films above 50% phase separation of the polymers is observed. Using the methods of dynamic mechanical analysis and X-ray diffraction the structural organization of the films is studied, the temperatures of relaxation transitions are determined, and the mechanical characteristics of the composite films are investigated.

Electroconductive scaffolds of different shape for tissue engineering have been obtained on the basis of two biocompatible polymers: polylactide and polypyrrole. The composite scaffolds have been based on porous permeable films or tubes of polylactides prepared via electrospinning. A layer of electroconductive polypyrrole has been applied at the developed surface of the scaffolds consisting of the chaotically interwoven fibers of micron-scale thickness. The structure of the tissue engineering scaffolds as well as their mechanical, redox, and electroconductive properties have been investigated. It has been found that the scaffolds are stable during electrical stimulation via prolonged application of the cyclic potentials.

Using fibroin derived from Bombyx mori silkworm cocoons multifunctional hemosorbents for the detoxification of blood and blood serum are obtained. Their physicochemical and morphological properties and sorption behavior are studied. It is shown that the resulting hemosorbents exhibit a high sorption activity. In terms of sorption activity, the hemosorbent based on fibroin treated by ultrasound and microwave irradiation ranks above the commercial hemosorbent VNIITU-1 in the Gemos^®-KS hemosorption column (NPP Biotech-М).

Free-radical copolymerization in bulk has afforded copolymers of N-vinylcaprolactam and N‑vinylimidazole (40–60 mol %). Thermosensitive behavior of aqueous solutions of the copolymers has been probed over wide pH range by means of dynamic and static light scattering as well as high-sensitivity differential scanning calorimetry. Three regions of thermally induced conformational behavior have been observed with the change in the medium pH from the alkaline to acidic: phase separation region (I), region of the conformational transition into the mesoglobules state (II), and region of stable molecular solution of the poly-electrolyte (III). Significant polyelectrolyte effects have been revealed for the salt-free solutions of the copolymers, reflected in the presence of fast and slow diffusion modes in the relaxation time distributions. Moderate increase in the ionic strength with the addition of the low-molecular salt has led to shielding of the polyelectrolyte effects, yet the pH-dependent regions of the conformational behavior have not been affected much. The existence of different types of the thermally induced conformational behavior depending on pH has been explained by the balance between hydrophobic interactions involving the N-vinylcaprolactam units and electrostatic interactions of the weakly basic N-vinylimidazole units.

With the rapid development of 5G communication and electronic manufacturing technologies, and other fields, the performance of products has improved, and thermal conductivity of materials demands have increased significantly. In this study, using a two-step method, hybrid filler networks were constructed in a polyurea (PUA) matrix with different filler ratios (aluminum nitride (AlN) and boron nitride (BN)), and the synergistic effects of the as-obtained thermal conductivity networks were investigated. The thermal conductivity of the hybrid filler/PUA composites was better than when a single filler was used. The thermal conductivity was maximum (54.24% higher) when the mass ratio of AlN : BN was 5 : 5, and the material had good heat resistance (T_g = 188°C), high tensile strength (12 MPa), and elongation at break (400%). The developed low-cost, high-performance hybrid composite filler has excellent application prospects for practical applications.