Fabrication of Core/Shell Nanofibers with Desirable Mechanical and Antibacterial Properties by Pickering Emulsion Electrospinning

To endow nanofibers with the desirable antibacterial and mechanical properties, a facile strategy using Pickering emulsion (PE) electrospinning is proposed to prepare functional nanofibers with core/shell structure for the first time. The water‐in‐oil (W/O) Pickering emulsion stabilized by oleic acid (OA)‐coated magnetite iron oxide nanoparticles (OA‐MIONs) is comprised of aqueous vancomycin hydrochloride (Van) solution and poly(lactic acid) (PLA) solution. The core/shell structure of the electrospun Van/OA‐MIONs‐PLA nanofibers is confirmed by scanning electron microscopy and transmission electron microscopy observation. Sustained release of Van from the PE electrospun nanofiber membrane is achieved within the time of 600 h. Compared with the neat PLA electrospun nanofiber membrane, 57% increase of tensile strength and 36% elevation of elongation at break are achieved on PE electrospun nanofiber membrane. In addition, the PE electrospun nanofiber membrane demonstrates excellent antibacterial property stemming from the combinational antibacterial activities of OA‐MIONs and Van. The Van‐loaded PE electrospinning nanofibers with sustained antibacterial performance possess potential applications in tissue engineering and drug delivery.

     

Fabrication and Characterization of Highly Oriented Composite Nanofibers with Excellent Mechanical Strength and Thermal Stability

Here, highly‐oriented poly(m‐phenylene isophthalamide)/polyacrylonitrile multi‐walled carbon nanotube (PMIA/PAN‐MWCNT) composite nanofiber membranes with excellent mechanical strength and thermal stability are successfully produced using electrospinning. It is demonstrated that the cooperation of multi‐walled carbon nanotubes (MWCNT) and high‐speed rotating collection is beneficial to the acquisition of highly oriented fibers and effectively improves the mechanical strength of the membrane along the orientation direction. Specifically, the tensile stress of poly(m‐phenylene isophthalamide)/polyacrylonitrile (PMIA/PAN) membrane is enhanced significantly from 10.6 to 20.7 MPa, benefiting from the highly oriented alignment of the fibers as well as the reinforcing effect of MWCNTs on the fibers. Furthermore, the stressing process of single fiber and fiber aggregates is carefully simulated, and the influence of MWCNTs on the mechanical properties of PMIA/PAN‐MWCNT membranes is analyzed comprehensively, providing a meaningful auxiliary means for the study of mechanical properties. In addition, the composite nanofiber membrane has the advantages of both PMIA and PAN, possessing high temperature resistance, flame‐retardancy, and chemical stability, for an ideal high‐temperature material. In short, the as‐prepared PMIA/PAN‐MWCNT composite membrane with excellent comprehensive property emerges a promising application in many fields, especially in high‐tech.     

核壳结构纳米TiO_2/PU/PMMA复合材料制备及其光催化性能研究

采用纳米TiO2有机化改性、加成及原位乳液聚合,制备了纳米TiO2、聚氨酯(PU)、聚丙烯酸酯(PMMA)的复合材料。透射电镜形貌表明:合成了以纳米TiO2为核,PU与PMMA为壳的核壳结构的复合材料。研究了该复合材料的光催化性能。     

Fabrication and Dielectric,Mechanical, and Thermal Properties of Low-Density Polyethylene (LDPE) Composites Containing Surface-Passivated Silicon (Si/SiO2 Core/Shell Nanoparticles)

Composites of low-density polyethylene containing between 1 and 5?wt% of Si/SiO₂ core/shell nanoparticles were prepared by ball milling method. The thermal, mechanical, and dielectric properties of composites were investigated in terms of composition, frequency, and temperature. The results showed that the dielectric permittivity increased smoothly with a rise of Si/SiO₂ particle. The dielectric permittivity and loss decreases and increases with temperature, respectively. The resistance of composites to erosion due to partial discharge was significantly improved by adding nanoparticles. The results have demonstrated that ball milling was an effective method for producing relatively homogeneous nanocomposite up to 4?wt% Si/SiO₂.     

壳核结构SiC/C纤维的制备与吸波性能的研究

采用活性碳纤维转换法制备了壳核结构SiC/C纤维,采用拉曼光谱、SEM、XRD以及热重分析等测试方法对比研究了生成SiC的厚度对壳核结构SiC/C纤维样品的热重及吸波性能的影响.结果表明:包裹SiC壳层后样品吸波性能得到提高,样品厚度为3.0 mm时,保温4 h样品的最小反射损耗在8.24 GHz处达到-17.22 d...     

核/壳苯丙乳液的合成

采用预乳化工艺和种子乳液聚合技术合成了具有核／壳结构的苯丙乳液，研究了引发剂种类、乳化剂用量及两阶段用量等对苯丙核／壳乳液合成的影响。得到了聚合过程稳定、综合性能好的核／壳型乳液。     

Cross-linked Chitosan/Thermoplastic Starch Reinforced with Multiwalled Carbon Nanotubes Using Maleate Esters as Coupling Agent: Mechanical,Tribological and Thermal Characteristics

Bio-nanocomposites have been developed using cross-linked chitosan and cross-linked thermoplastic starch along with acid functionalized multiwalled carbon nanotubes (f-MWCNT). The nanocomposites developed were characterized for mechanical, wear, and thermal properties. The results revealed that the nanocomposites exhibited enhanced mechanical properties. The composites containing 3% f-MWCNT showed maximum compression strength. Tribological studies revealed that, with the addition of small amount of f-MWCNTs the slide wear loss reduced up to 25%. SEM analysis of the nanocomposites showed predominantly brittle fractured surface. Thermal analysis showed that the incorporation of f-MWCNTs has improved the thermal stability for the nanocomposites.     

Morphology,Thermal Stability,and Electrical Conductivity of Polymer Nanocomposites of Isotactic Polypropylene/Multi-Walled Carbon Nanotubes

Molecular weight of isotactic polypropylene (iPP) and concentration of multi-walled carbon nanotubes (MWCNT) effects on the morphology, thermal stability, and electrical conductivity for iPP/MWCNT nanocomposites were evaluated. Nanocomposites were prepared by solution mixing followed by non-isothermal crystallization from the melt. The samples were characterized by different physical-chemical techniques. Electrical conductivity was obtained from electrical resistance measured using a source meter. It was determined that the morphology of the nanocomposites shows a change from spherulitic to fibrillar to undefined depending on the molecular weight of iPP and concentration of MWCNT. Morphology was correlated with thermal stability and electrical conductivity.     

Amphiphilic Core/Shell Nanoparticles to Reduce Biocide Leaching From Treated Wood, 1 – Leaching and Biological Efficacy

Core/shell nanoparticles containing the fungicide tebuconazole were prepared from amphiphilic copolymers of gelatin grafted with MMA. The grafting was performed in water at levels of 1.5–15 wt.‐% solids based on matrix mass, to give core/shell nanoparticles with median diameters ranging from ≈200 to 400 or ≈10 to 100 nm depending on composition, conditions used, and work‐up. The biocide‐containing nanoparticles were delivered into wood in up to 85% efficiency. Wood blocks treated with tebuconazole‐containing nanoparticles leached less tebuconazole than wood blocks treated with tebuconazole solutions. The best nanoparticle formulations afforded wood blocks with a biological efficacy comparable to solution‐treated wood block controls in soil jar decay tests.