Macromolecular Materials and Engineering最新文献

Three-dimensional (3D) printing is an innovative manufacturing method for preparing designer materials with complex geometries. However, there are very few studies on the fabrication of antimicrobial polymer materials suitable for use in everyday clinical objects, via 3D printing. In this work, an antibacterial polymer material is prepared by blending polyamide 11 (matrix), a high-performance engineering thermoplastic, and a styrene maleimide copolymer with pendant quaternary amine moieties, and the blend 3D printed via selective laser sintering. The quaternary amine functionalities confer permanent antimicrobial properties. Blend properties are studied prior to printing via differential scanning calorimetry, powder X-ray diffraction, and FTIR spectroscopy. Additionally, the mechanical and antimicrobial properties of the polymer blends and printed material are also assessed. The microstructure of the 3D printed polymer materials is further characterized via DOSY NMR spectroscopy. This study indicates that this is a promising approach for preparing nonleaching antimicrobial 3D printable materials.

In this study, modified nano zinc oxide (ZnO)-reinforced polymer-supported novel thermally enhanced form-stable composite phase change materials (PCMs) are presented, which are prepared via water in oil emulsion polymerization and following impregnation process steps. First, ZnO nanoparticles are modified with oleic acid (OA) to obtain lipophilic structures for emulsion stability, which are designed to take a role as a heat transfer activator. To ensure the shape stabilization of n-hexadecane used as organic PCM, polymeric support materials are synthesized in the presence of modified ZnO nanoparticles (ZnO@OA). The polymeric frameworks exhibit open porous morphology, and the thermal stability of the support matrix improves with the addition of ZnO nanofiller. In the second step, composite PCMs are prepared by incorporation of n-hexadecane with the solvent-assisted vacuum impregnation method into polymer composites. The 1.0% ZnO@OA incorporated composite PCM has the highest incorporation ratio and exhibits a thermal storage capability (η) of 100%. According to the T-history and thermal conductivity tests, it is observed that the heat conduction rate is enhanced with the addition of ZnO@OA nanofiller. The conclusion is that the obtained ZnO@OA integrated composite PCMs have a remarkable potential for latent heat storage applications requiring low temperature in the range of 5–25 °C.

This article reports the coexistence of hardening and softening phenomena when polyurea is submitted to repeated nano-impacts with various impact forces while controlling the strain rate. The manifestation of these phenomena is further elucidated by interrogating ultraviolet irradiated samples under ambient and nitrogen atmospheres, wherein artificial weathering accelerates hardening by reducing the nano-impact depths as a function of exposure duration while increasing the impact load, nano-impact repetitions and strain rate sensitivity favored softening. A 21% and 48% increase in indentation depth are recorded after 100 repetitions at a relatively higher force (10 mN) at a low strain rate and low force (2.5 mN) at a relatively higher rate for pristine and weathered polyurea, respectively. Electron microscopy evidences the induced, progressive damage at the nanoscale based on the agglomeration of hard segments, reduced free volume, and weathering-induced surface embrittlement.

In the study, a new strategy is presented to make PLGA (poly lactic-co-glycolic acid) and POEGMEMA (poly(oligo(ethylene glycol) methyl ether methacrylate)) based biodegradable and biocompatible tissue scaffold via a new physical cross-linking method. The advantage of brushed structure of POEGMEMA polymer and the hydrophobic character of PLGA polymer is taken to make physically entangled network in aqueous media. The hydrophobic nature of PLGA allows to get scaffolds even at low ratio of PLGA (25%, w/w) when using POEGMEMA (yield: 86%). This strategy gives robust polymeric networks in aqueous media without using chemical reactions through high hydrophilic polymer content. Scaffolds with high POEGMEMA ratio (75%, w/w) show two times higher water uptake ratio (≈300%) and two times lower compression strength (19 kPa) compared to the ones with lower POEGMEMA content (50%, w/w). They also show desired degradation profiles in various aqueous solutions. While the scaffolds prepared with 25% and 50% PLGA are almost stable in first 20 days, they completely degrade in 40–50 days. Both scaffold formulations (25% PLGA-75% POEGMEMA and 50% PLGA-50% POEGMEMA) have similar proliferative properties for fibroblast cells. The scaffolds also do not show toxicity compared to control group according to live-dead assay.

Obtaining a polymer nanocomposite with optimum viscoelastic, thermal, and biocompatibility properties is the main objective when designing nanocomposite systems with potential applications in tissue engineering. For this purpose, a blend of Polycaprolactone (PCL) and Polyvinylidene fluoride (PVDF) in an 85/15 weight ratio, along with a nanocomposite reinforced by nanohydroxyapatite (nHA) particles, is fabricated using a solution casting method in a mold. The impact of nHA content on crystallinity, viscoelastic properties, thermal stability, and the properties–structure relationship of nanocomposites is evaluated using scanning electron microscopy (SEM). Dynamic mechanical thermal (DMTA) analysis is used to determine the William–Landel–Ferry (WLF) constants and the effect of nHA on the nanocomposite's viscoelastic behavior. The PCL/15PVDF/0.5 wt% nHA exhibits the maximum thermal stability (40% residual char value) and 95% increase in storage modulus at 90 °C (rubbery region) in comparison with PCL/15PVDF blend. Water contact angle (WCA) and biocompatibility tests are conducted on the PCL/15PVDF blend and nanocomposite scaffolds to design appropriate nanocomposite systems with potential applications in tissue engineering. The high hydrophilic properties are assigned to PCL/15PVDF/0.5 wt% nHA with a WCA of 67.5°. Finally, in vitro cell culture confirmed 0.5 wt% nHA significantly improves cell adhesion and cytotoxicity with MG-63 cells.

This study investigates the chemical–physical properties and anticorrosion effectiveness of UV-cured coatings produced using epoxidized vanillin (DGEVA) as biobased precursor, then reinforced by the addition of nanoclay. After optimizing the UV-curing parameters of three different formulations by Fourier transform infrared spectroscopy (FTIR), the thermo-mechanical properties of the coatings are assessed by differential scanning calorimetric analysis (DSC), dynamic thermal mechanical analysis (DTMA), and pencil hardness. The coatings are applied on mild steel substrates and then their barrier properties are investigated by electrochemical impedance spectroscopy measurements, immersing the samples in 3.5 wt% NaCl aerated solutions. The results show the good corrosion protective effectiveness of the biobased coatings. The nanoclay addition has a beneficial effect, as it hinders the diffusion of the aggressive ions from the electrolyte solution to the metal substrate. The reported findings demonstrate the possibility of using biobased precursors and UV-curing technology to reduce the environmental impact of the coating industry.

Sucrose and glycerol have gained attention as additives for hydrogels, owing to their capacity to exert considerable influence over the physicochemical, mechanical, and biological characteristics of these materials. Herein, these effects on agarose hydrogels (AHs) are explored. A series of AHs are synthesized using sucrose (30% and 300% w/v) and glycerol as additives. The storage modulus (10.0–13.7 kPa) and hydrophilicity of the hydrogels (contact angle < 50°) do not vary significantly with sucrose or glycerol addition. However, sucrose enhances the hydration capacity of the hydrogels by up to 170%, whereas glycerol reduces it. Interestingly, sucrose and glycerol individually do not have bacteriostatic effects against Staphylococcus epidermidis, but their combination significantly (p ≤ 0.001) inhibits the growth of both S. epidermidis and Pseudomonas aeruginosa by 63% and 29%, respectively, in comparison to native agarose. Cytotoxicity testing on NIH/3T3 murine fibroblasts reveals that sucrose increases cell viability up to 98%, while glycerol reduces it below 60%. Overall, these hydrogels hold promise for antibacterial biomedical applications as wound dressing materials and surface coatings for medical devices and can also be used to formulate bioinks for 3D bioprinting.

The significance of hydrogen energy has grown considerably due to climate change and the depletion of fossil fuels. PEM fuel cells are the key hydrogen technologies. Commercial membranes based on perfluorosulfonic acid (PFSA) with a polymer structure containing fluorine are currently available. However, it has been determined that certain perfluorosulfonic acids (PFSAs) are hazardous, persistent, and bioaccumulative. Advancements in hydrogen technology rely on effective, inexpensive, and perfluorocarbon-free membranes, specifically proton exchange membranes (PEMs). In this research, a PFSA-free polyacrylonitrile-co-methyl acrylate (PAN-MA) membrane doped with phosphoric acid is prepared using the electrospinning method and then characterized by SEM, FE-SEM, XRD, FTIR, TGA, DMA, and EIS. The DMA analysis reveals that the storage modulus of the doped membrane increases from 0.98 to 5.66 MPa at 80 °C. The nanofiber composite membrane, with a thickness of 181 µm, exhibits the highest proton conductivity of 0.306 S m⁻¹ at 20 °C, 1.76 times higher than that of the Nafion 212 membrane. The Nafion 212 membrane has an ionic conductivity of 0.173 S m⁻¹ under the same conditions. These results indicate that the prepared nanofiber membranes are promising materials for evaluating fuel cell applications.