Polymer Science, Series A最新文献

Due to wide application of biomaterials in drug delivery systems for wound healing, this research work is focused on the development and characterization of a Gelatin/Glycerol composite film for delivering the antibiotic Erythromycin. The aim was preparing gelatin/glycerol films loaded with erythromycin suitable for a future application as a patch for skin wound healing application. A set of films were prepared with various gelatin to glycerol weight ratio and the impact of glycerol content on the mechanical, physicochemical and thermal behavior of film evaluated. Erythromycin was loaded into the film and the antibacterial activity evaluated versus E.coli and S.aureus. Results demonstrate a correlation between the content of glycerol and the physico-chemical properties of the film. The Ge/GY films containing the drug show good antibacterial effects only against Staphylococcus aureus bacteria. TGA and DSC of Ge/ GY thin films showed thermal stability until 110°C, however, the complete decomposition occurred at 350°C.

Dual-modal fluorescent/magnetic resonance imaging attracts more and more attentions in biomedical applications. Herein, star-shaped poly(ε-caprolactone)-b-poly(N-vinylpyrrolidone) amphiphilic copolymer with a tetrakis-(4-amino)-terminated tetraphenylethylene core was synthesized. Then, dual-functional nano micelles were achieved via a facile self-assembly of the star copolymer and in situ encapsulation of iron oxide nanoparticles. The fluorescent characteristic of the tetraphenylethylene moiety and encapsulation of iron oxide endowed the resultant dual-functional micelles with bright fluorescence and superparamagnetic properties, which indicated that the PCL segments coated on magnetic nanoparticles is effective at separating the conjugated core from iron oxide nanoparticles to minimize fluorescence quenching. The obtained micelles were found to have a good colloidal and fluorescent stability in different environment. In vitro studies revealed that these dual-functional micelles could serve as an effective fluorescent probe to achieve imaging of MCF-7 cells without obvious cytotoxicity. Thus, this work provides a facile strategy to fabricate fluorescent-magnetic dual-functional micelles for dual-modal imaging applications.

To study the effects of graphene oxide (GO) dimension on the mechanical and dielectric performance of epoxy resin (EP), two kinds of GO with different dimensions were selected and characterized by Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results showed that the two kinds of GO had similar chemical structure, but different average particle sizes of 190.1 nm (SGO) and 1510 nm (MGO), respectively. The mechanical properties, dynamic mechanical properties, and dielectric properties of the EP/GO composites are analyzed using electronic universal testing machine, Rockwell hardness tester, dynamic mechanical analysis (DMA) and broadband dielectric impedance relaxation spectrometer. Results revealed that the GO dimension plays important role in determining the dispersion of the filler in EP matrix, and further determines the mechanical properties and dielectric performance of the composites. EP/SGO with better dispersion of GO in the EP matrix exhibits better mechanical properties, higher glass transition temperature, higher dielectric constant. Related mechanism has been proposed.

Biodegradable poly(ɛ-caprolactone) (PCL), which is used in bioengineering applications thanks to its mechanical and biodegradable properties, it used as a polymer matrix in this study. The nanocomposite of PCL reinforced with recycled red mill scale PCL/RS has been prepared via ultrasonic mixing by solution casting technique at different amounts of RS (1, 5, 10, and 20 wt %), while virgin PCL was also produced for comparison. The structural, thermal, mechanical, and optical behaviors of PCL/RS nanocomposite films have been investigated. Raman spectroscopy shows that small amounts of particles ≤10 wt % may act as nucleation sites for the growth of polymer crystallites; While large amounts of particles will destroy crystallization zones. Blue shifts in spectrum Raman might be caused by the electronic interactions associated with charge transfer between PCL and RS nanoparticles. The XRD results is in good agreement with the Raman results that the crystallinity of esters increases in PCL/RS 10 wt % film. The melting temperature T_m of the nanocomposites is in the order of PCL/RS 1 wt % (71.1°C) > PCL/RS 5 wt % (71°C) > PCL/RS 10 wt % (70.3°C). We note that it has a resemblance in the values established by DRX and DSC, the crystallinity rate increases with the increase in the filler content 45 < 47 < 69 < 74.5. The nanocomposite materials prepared have UV-protective properties. Tensile results increase with an slight increase in RS filler at 5 wt % is 2 MPa, in comparison with PCL/RS 10 wt % (~1 MPa this result yields flexibility of the film and indicates good dispersion of RS in nanocomposite, resulting better interfacial adhesion.

The effect of ZrO₂ nanoparticles on the structural, electrical, and dielectric properties of polyaniline was studied. ZrO₂ nanoparticles with an average size of 8 nm were synthesized by a simple precipitation method and their tetragonal and monoclinic crystalline phase was confirmed. Polyaniline and its nanocomposite with ZrO₂ have been synthesized by chemical oxidation method using CH₃COOH as a doping agent and APS as an oxidant. The synthesized composites were analyzed by infrared spectroscopy, X-ray diffraction, scanning electronic microscopy, AC conductivity, dielectric and impedance spectroscopy. In Nyquist plots, systematic decrement in the semicircle size was observed with growth of ZrO₂ content. The dielectric constant in the PANI/ZrO₂ composite has been increased with an increase in weight content of ZrO₂ in PANI matrix and exhibited the Maxwell–Wagner–Sillars effect.

In the present investigation synthesis of Xanthan Gum (XG-g-PAAcoAM), Lignosulphonate sodium salt (LS-g-PAAcoAM), and their combination (XG/LS-g-PAAcoAM) based hydrogels by grafting them onto acrylic acid and acrylamide for efficient removal of Methylene Blue dye have been reported. The results were found to be reliable with a removal rate exceeding 91% when administered at a dosage of 0.2 g in a 20 mL solution of Methylene blue dye over a period of 7 h. The hydrogels have been characterized by various techniques using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction analysis. Among the three commonly used isotherms (Langmuir, Freundlich, and Temkin), the Freundlich isotherm model exhibits the highest level of fit for the dye adsorption as evident with the R² value of 0.99. This study provides a meaningful comparative insight towards using these natural polymers i.e., XG and LS as feedstock for hydrogel synthesis and efficient adsorbent for wastewater treatment applications.

The surface modification of polycaprolactone and polycaprolactone/polylactide mixed films was carried out by preliminary surface activation in NaOH. Subsequent layer-by-layer deposition of coatings based on polyelectrolyte complexes of the oppositely charged polysaccharides: chitosan and hyaluronic acid, was carried out. The effect of surface activation was studied using contact angle measurements, surface analysis and gravimetric data. The characterization of the polyelectrolyte complex coatings using gravimetric analysis, goniometric and micrometer measurements, scanning electron, optical and fluorescence microscopy, and FTIR-ATR spectroscopy confirmed the formation of a uniform coating with a thickness of about 30 μm, which is not prone to peeling from the substrate.

The synthesis of peptide nanocomposites from water-soluble components has many advantages. However, this raises the question of maintaining the functional properties and chemical structure of composites solid layers during long-term storage at ambient conditions. The processes of structural transformations during different stages of crystallization of hectapeptide composites with silver and gold nanoparticles in humid atmosphere were studied. The influence of temperature, humidity, nature of the substrate, its wetting, conformation of peptide molecules on the structure and electrophysical properties of the composites was considered also. Similarly to polymers two stages of crystallization were found: the initial fast and the subsequent slow. Unlike polymers, an increase in temperature does not affect this process, but even slows it down. Despite significant changes in the surface morphology of composites their electrophysical properties and conformation of molecules do not change. An increase in humidity accelerates the processes of the structural transitions. The results show that the changes in the surface morphology of PT composites under the influence of humidity relate only to the PT matrix itself and not to their locations or conformation of molecule.

Basalt fibres are gaining interest in the fibre-reinforced thermoplastic industries around the world. In this work, basalt and glass short fibres reinforced polypropylene composites were produced using twin-screw extrusion and followed by injection molding. To carry out a comprehensive study on physical and mechanical properties, the composites were produced with different proportions of fibre loadings (for both fibres 5, 10, and 20 wt %). Composites were characterized and studied for tensile (at different strain rates), flexural (at different speeds), impact, dynamic mechanical analysis, density, tensile-relaxation, melt flow index test, and rheometric properties. Results indicate that tensile, flexural, dynamic mechanical analysis, and tensile-relaxation properties increased with increasing fibre proportions in the polypropylene matrix. The melt flow and rheometric behaviors of polypropylene decreased significantly with the addition of short fibres into the matrix. The overall results showed that basalt fibres can be potentially used as replacements for glass fibre to develop these thermoplastic composites.

Perpendicular di-block copolymer domains are produced when poly(styrene-block-methylmethacrylate (PS-b-PMMA) is spun onto a disordered layer of zinc oxide nanoparticles, followed by thermal annealing in vacuum. The ZnO layer creates a rough surface on the silicon substrate, inducing vertical cylinders of PMMA. The subsequent development of a PS template is illustrated. The wet etching process removed the vertically oriented PMMA nanodomains in the PS matrix. The morphology of the PS mask showed ordered nanopores with diameters around 20 nm. The effect of surface roughness and di-block film thickness on forming perpendicular cylindrical domains of PS-b-PMMA is analyzed. For a typical thickness of PS-b-PMMA film around 33 nm, a specific surface roughness parameter of 0.07 is obtained. These results are compared with other reports on this topic.