聚合物对硫化铅钠米微粒的稳定作用

以含铅聚合物微凝胶与Ｈ２Ｓ气体反应制得ＰｂＳ纳米微粒／聚合物复合体系，利用小角Ｘ光散射方法对复合在聚合物中的ＰｂＳ纳米微粒的粒度及分布进行了表征，研究了不同反应条件对其粒度及复合体系稳定性的影响。     

Amorphous calcium phosphate/poly(D,L-lactic acid) composite nanofibers: electrospinning preparation and biomineralization

Amorphous calcium phosphate (ACP) has been recognized as an attractive biomaterial due to its bioactivity and biocompatibility. Electrospinning is a simple and low-cost way to fabricate polymer fibers. In this study, ACP nanoparticles with diameters ranging from 20 to 80 nm were synthesized using a simple precipitation method. ACP nanoparticles were hybridized with poly(D,L-lactic acid) (PDLLA) to form ACP/PDLLA composite nanofibers by electrospinning, and different architectures including the nanofibrous mesh and tube consisting of ACP/PDLLA composite nanofibers were obtained and characterized. The biomineralization and cytocompatibility of as-prepared ACP/PDLLA composite nanofibers were evaluated in vitro. Osteoblast-like MG63 cells were seeded on the ACP/PDLLA composite nanofiber meshes to perform the cytocompatibility evaluation. The ACP/PDLLA composite nanofibers exhibited a fast mineralization behavior in the simulated body fluid. The attachment of MG63 cells and cytotoxicity of ACP/PDLLA composite nanofibers were also evaluated, and the experiments indicated good biocompatibility and bioactivity of ACP/PDLLA composite nanofibers.     

Controlled fabrication of cross-linked nanoparticles/polymer composite thin films through the combined use of surface-initiated atom transfer radical polymerization and gas/solid reaction

A promising strategy for the controlled synthesis of inorganic/polymeric nanocomposites may be sustained by fabricating cross-linked PbS nanoparticles/polymer composite thin films through combining surface-initiated atom transfer radical polymerization (ATRP) and gas/solid reaction. The introduction of Pb ions through the extension of surface-initiated ATRP to the monomers containing metal ions provides an opportunity for generating nanoparticles on the substrate.     

Preparation and characterization of porous TiO_2/ZnO composite nanofibers via electrospinning

<正>Porous TiO_2/ZnO composite nanofibers have been successfully prepared by electrospinning technique for the first time.It was generated by calcining TiO_2/ZnCl_2/PVP[PVP:polyvinyl pyrrolidone)]nanofibers,which were electrospun from a mixture solution of TiO_2,ZnCl_2 and PVP.Transmission electron microscopy(TEM) and X-ray diffraction(XRD) analyses were used to identify the morphology of the TiO_2/ZnO nanofibers and a formation of inorganic TiO_2/ZnO fibers.The porous structure of the TiO_2/ZnO fibers was characterized by N_2 adsoption/desorption isotherm.Surface photovoltage spectroscopy(SPS) and photocatalytic activity measurements revealed advance properties of the porous TiO_2/ZnO composite nanofibers and the results were compared with pure TiO_2 nanofibers,pure ZnO nanofibers and TiO_2/ZnO nanoparticles.     

Encapsulation and selective recognition of molecularly imprinted theophylline and 17beta-estradiol nanoparticles within electrospun polymer nanofibers

Molecularly imprinted nanoparticles are cross-linked polymer colloids containing tailor-made molecular recognition sites. In this study, molecularly imprinted nanoparticles were easily encapsulated within polymer nanofibers using an electrospinning technique to produce a new type of molecular recognition material. Poly(ethylene terephthalate) (PET) was used as the supporting nanofibers matrix to encapsulate theophylline and 17beta-estradiol imprinted nanoparticles. The composite nanofibers had an average diameter of 150-300 nm, depending on the content of molecularly imprinted nanoparticles. For the theophylline and 17beta-estradiol imprinted polymers, an optimal loading of molecularly imprinted nanoparticles was 25-37.5 wt % based on PET. The composite nanofibers prepared under these conditions had a well-defined morphology and displayed the best selective target recognition. Our approach of electrospinning-for-molecularly imprinted nanoparticles-encapsulation has unique advantages and opens new application opportunities for molecularly imprinted nanoparticles and electrospun nanofibers.     

Novel fabrication of magnetic thermoplastic nanofibers via melt extrusion of immiscible blends

A novel technique of fabricating magnetic thermoplastic nanofibers by the control of the phase separation of immiscible polymer blends during melt extrusion was presented. The magnetic poly(vinyl alcohol‐co‐ethylene) (PVA‐co‐PE)/Fe₃O₄ composite nanofibers were prepared via the melt extrusion of cellulose acetate butyrate matrix and PVA‐co‐PE preloaded with different amounts of Fe₃O₄ nanoparticles. The morphologies of magnetic composite nanofibers were characterized by scanning electron microscopy. The uniform dispersion of Fe₃O₄ nanoparticles in nanofiber matrixes and crystal structures were confirmed using transmission electron microscopy and wide angle X‐ray diffraction. Thermogravimetric analysis was employed to quantify the exact loading amount of Fe₃O₄ nanoparticles in the composite nanofibers. The magnetic measurements showed that composite nanofibers displayed superparamagnetic behavior at room temperature. With increasing content of Fe₃O₄ nanoparticles, the saturation magnetization of the magnetic composite nanofiber significantly improved. The prepared magnetic composite nanofibers might have found potential applications in the sensors and bio‐molecular separation fields. Copyright © 2012 John Wiley & Sons, Ltd.     

Photophysics and charge dynamics of Q-PbS based mixed ZnS/PbS and PbS/ZnS semiconductor nanoparticles

The surface of ZnS and PbS has been modified by interfacing PbS on ZnS and ZnS on PbS nanoparticles. This produced core-shell nanocomposites ZnS/PbS and PbS/ZnS with tunable electronic properties. In both structures PbS particles are present in cubic form with an average diameter of about 6 nm. The addition of Pb2+ (3 x 10(-4) mol dm(-3)) to Q-ZnS (1.5 x 10(-4) mol dm(-3)) in the basic pH range produces size-quantized fluorescent PbS particles coated by metal hydroxides. In these particles the relaxation kinetics of charge carriers has been followed using a picosecond single-photon counting technique. At 1.5 x 10(-4) mol dm(-3) Pb2+ an interfacial relaxation of charge from ZnS to PbS phase could be observed in subnanosecond time domain. An increase in [Pb2+] from 2 x 10(-4) to 1 x 10(-3) mol dm(-3) enhanced the average emission lifetime from 9.4 to 19.4 ns. Composite PbS/ZnS particles are produced at high [ZnS] only. These particles had emission lifetime in mus time range. The extent of charge separation and the dynamics of charge carriers could be manipulated by the surface modification of these nanostructures.     

Fabrication of a metal nanoparticles and polymer nanofibers composite material by an in situ chemical synthetic route

This work demonstrated a facile route for the synthesis of poly(3,5-dimethyl aniline) nanofibers by polymerization of 3,5-dimethyl aniline using Pd-acetate as the oxidant. The reduction of Pd ion is accompanied by oxidative polymerization of 3,5-dimethyl aniline, leading to a metal-polymer composite material. Palladium nanoparticles (approximately 2 nm) are uniformly distributed throughout the polymer that makes the composite material a unique morphology. The resultant composite material was characterized by means of different techniques. IR and Raman spectra provide the information on the chemical structure of the polymer. TEM images show the morphology of the polymer and size of the metal particles.     

用软刻蚀方法制备PbS纳米晶复合聚丙烯酸微图形

PbS microstructures have several applications such as Pb2+ion-selective sensors and IR detector.The method to prepare PbS nanocrystal embed in poly(acrylicacid) (PAA) microstructures produced by means of soft lithography and solid state polymerizatio n by γ-ray irradiation was described. PbS micro patterns were prepared by Micro molding in Capillaries (MIMIC) with aqueous solution of acrylic acid lead monomer, and then solid state polymerized by γ-ray irradiation. Finally, the sample was treated with aqueous solution of Na2 Stoconvert the Pb2+ to PbS in the matrix. High-resolution micro structures of PAA, which have PbS nanocrystals embedded in them, could be produced successfully in this way. The final products were characterized by TEM, XRD, and XPS. TEM image indicated that the PbS particles embedded in PAA had a diameter of smaller than 20nm. X-ray powder diffraction method was also used to characterize the PbS/PAA nanocomposite film. The XPS analysis showed the element Pb has been converted to PbS nanoparticles in the composite films.     

NiSe2 nanoparticles encapsulated in CNTs covered and N-doped TiN/carbon nanofibers as a binder-free anode for advanced sodium-ion batteries

Metal selenides are promising anodes for sodium-ion batteries (SIBs) due to the high theoretical capacity through conversion reaction mechanism. However, developing metal selenides with superior electrochemical sodium-ion storage performance is still a great challenge. In this work, a novel composite material of free-standing NiSe₂ nanoparticles encapsulated in N-doped TiN/carbon composite nanofibers with carbon nanotubes (CNTs) in-situ grown on the surface (NiSe₂@N-TCF/CNTs) is prepared by electrospinning and pyrolysis technique. In this composite materials, NiSe₂ nanoparticles on the surface of carbon nanofibers were encapsulated into CNTs, thus avoiding aggregation. The in-situ grown CNTs not only improve the conductivity but also act as a buffer to accommodate the volume expansion. TiN inside the nanofibers further enhances the conductivity and structural stability of carbon-based nanofibers. When directly used as anode for SIBs, the NiSe₂@N-TCF/CNT electrode delivered a reversible capacity of 392.1 mAh/g after 1000 cycles and still maintained 334.4 mAh/g even at a high rate of 2 A/g. The excellent sodium-ion storage performance can be attributed to the fast Na⁺ diffusion and transfer rate and the pseudocapacitance dominated charge storage mechanism, as is evidenced by kinetic analysis. The work provides a novel approach to the fabrication of high-performance anode materials for other batteries.     

A simple method for creating molecularly imprinted polymer-coated bacterial cellulose nanofibers

Molecularly imprinted polymer-coated bacterial cellulose nanofibers have been prepared by immersing solvent treated-bacterial cellulose into a dilute pre-polymerization mixture solution prior to the polymerization process. The quercetin-imprinted polymer coating bacterial cellulose (QIP-BC) nanofibers show discrete nanoparticles encapsulated along the BC nanofibers. The binding capacity of dried QIP-BC was approximately 3 mg per gram of the polymer. The obtained results indicated that QIP-BC nanofibers provided a three fold higher recognition ability for quercetin than quercetin-imprinted nanospheres. This technique can be easily used to combine two fascinating materials like BC nanofibers and molecularly imprinted polymers (MIPs) to afford promising polymer composites that are useful in various innovative applications in biomedical, pharmaceutical, and industrial sectors.     

Hierarchical porous nanofibers of carbon@nickel oxide nanoparticles derived from polymer/block copolymer system

The triblock copolymer (PAA-b-PAN-b-PAA) is prepared by reversible addition-fragmentation chain-transfer polymerization, and then blended with polymer (PAN) and metal hydroxide (Ni(OH)₂) as a precursor for heat-treatment. A composite material of hierarchical porous nanofibers and nickel oxide nanoparticles (HPCF@NiO) is prepared by electrospinning combined with high-temperature carbonization. The effects of the ratio of PAA and PAA-b-PAN-b-PAA on the internal structure of nanofibers and their electrochemical properties as positive electrode materials are investigated. The experimental results show that when the ratio of PAA to PAA-b-PAN-b-PAA is 1.3 to 0.4, it has good pore structure and excellent electrochemical performance. At the current density of 1 A/g, the specific capacitance is 188.7 F/g and the potential window is −1 V to 0.37 V. The asymmetric supercapacitor assembled with activated carbon as the negative electrode materials has a specific capacitance of 21.2 F/g in 2 mol/L KOH and a capacitance retention of 85.7% after 12,500 cycles at different current density.     

Palladium nanoparticles stabilized by chitosan/PAAS nanofibers: A highly stable catalyst for Heck reaction

Palladium chloride doped chitosan composite nanofibers were prepared by electrospinning with sodium polyacrylate (PAAS) as the co-spinning agent. The composite nanofibers are subsequently treated at elevated temperature to improve their solvent resistance. The Pd (II) cations inside the composite nanofibers were reduced into uniform palladium nanoparticles (Pd NPs) with mean diameter of ~4.93 nm. These Pd NPs inside the chitosan composite nanofibers exhibited excellent catalytic activity for Heck reactions of aromatic iodides with alkenes with yields over 85%. Moreover, due to the fibrous structure, this novel fibrous palladium catalyst could be readily recovered by simple filtration and reused for 18 times without loss of initial catalytic activity. It was found that the reactants could readily diffuse from the reaction solution to the active Pd NPs inside the nanofibers and the products could departure from composite fibers into the reaction solution, while the Pd NPs were tightly restricted inside the chitosan composite nanofibers.     

Synthesis of poly(o-phenylenediamine) hollow spheres and nanofibers using different oxidizing agents

Poly(o-phenylenediamine) (PoPD) hollow spheres (ca. 800 nm in outer diameter) were synthesized by a simple solution route using ammonium persulfate (APS) as the oxidizing agent, whereas PoPD nanofibers (0.5-2 μm in width and more than 100 μm in length) and gold nanoparticles (200-500 nm) were obtained when changing the oxidizing agent of APS to chlorauric acid (HAuCl₄). The chemical structures of PoPD hollow spheres and nanofibers were characterized by FTIR and XRD spectra. When using HAuCl₄ as the oxidizing agent, the products of PoPD nanofibers and gold nanoparticles could be separated by chemical methods. The monomer droplets were proposed to act as template to the formation of polymer hollow spheres while the oriented growth of polymer nanofibers might be catalyzed by gold nanoparticles.     

Controlled release of doxorubicin from electrospun MWCNTs/PLGA hybrid nanofibers

In this study, multiwalled carbon nanotubes (MWCNTs) were used to encapsulate a model anticancer drug, doxorubicin (Dox). Then, the drug-loaded MWCNTs (Dox/MWCNTs) with an optimized drug encapsulation percentage were mixed with poly(lactide-co-glycolide) (PLGA) polymer solution for subsequent electrospinning to form drug-loaded composite nanofibrous mats. The structure, morphology, and mechanical properties of the formed electrospun Dox/PLGA, MWCNTs/PLGA, and Dox/MWCNTs/PLGA composite nanofibrous mats were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and tensile testing. In vitro viability assay and SEM morphology observation of mouse fibroblast cells cultured onto the MWCNTs/PLGA fibrous scaffolds demonstrate that the developed MWCNTs/PLGA composite nanofibers are cytocompatible. The incorporation of Dox-loaded MWCNTs within the PLGA nanofibers is able to improve the mechanical durability and maintain the three-dimensional structure of the nanofibrous mats. More importantly, our results indicate that this double-container drug delivery system (both PLGA polymer and MWCNTs are drug carriers) is beneficial to avoid the burst release of the drug and able to release the antitumor drug Dox in a sustained manner for 42 days. The developed composite electrospun nanofibrous drug delivery system may be used as therapeutic scaffold materials for post-operative local chemotherapy.     

Electrospinning preparation and mechanical properties of PVA/HNTs composite nanofibers

In this paper, the PVA/HNTs composite nanofibers with well‐enhanced mechanical properties were successfully prepared by electrospinning technique. The structure and properties of the composite nanofibers were characterized by TEM, XRD, FT‐IR, and DSC. The results indicated that the highly oriented and dispersed HNTs wrapped in polymer matrix were achieved by inducing function during electrospinning processing. The mechanical properties of the PVA/HNTs composite nanofibers depended on HNTs content were investigated, which showed 72.4% increase in tensile strength at optimal filling content. Copyright © 2016 John Wiley & Sons, Ltd.     

球状、立方状及空心立方状PbS纳米晶的控制合成及其形成机理

以醋酸铅为铅源,硫代乙酰胺为硫源,在表面活性剂十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)共同作用下,通过简单地调节水热反应的反应温度控制合成出球状、立方状和空心立方状PbS纳米晶。利用XRD、TEM对合成产物的结构和形貌进行了表征,发现合成的球状、立方状和空心立方状PbS纳米晶尺寸均一,直径为100 nm左右。对球状、立方状和空心立方状PbS纳米晶的形成机理进行了初探,结果表明反应温度较低时,水热反应初始阶段形成的PbS小颗粒呈球形,在表面活性剂SDS的烷基链模板和CTAB微胶束软模板共同作用下生成球状PbS纳米晶;反应温度较高时,水热反应初始阶段形成的PbS小颗粒由于自身的立方相岩盐晶体结构的影响有呈立方状趋势,在SDS和CTAB共同作用下产物堆积成空心立方体状或立方状。     

Synthesis of TiO2/Bi2WO6 nanofibers with electrospinning technique for photocatalytic methyl blue degradation

TiO₂/Bi₂WO₆ composite nanofibers have been successfully synthesized by a simple electrospinning process. XRD, SEM, HR-TEM, nitrogen adsorption–desorption isotherms and UV–visible diffuse reflectance spectra were used to characterize the composite nanofibers. The composite fibers with diameters about 100 nm was composed of nanoparticles and possessed of high specific surface area (49.6 m² g^?1) and porous structure. Besides, the TiO₂/Bi₂WO₆ composite nanofibers exhibited excellent visible photocatalytic property in the photodegradation of methylene blue (MB), and over 97.2 % of MB was degraded within 5.5 h.     

Synthesis and properties of thermoresponsive magnetic polymer composites and their electrospun nanofibers

The thermoresponsive magnetic polymer composites and nanofibers were fabricated. Their thermal and magnetic properties were also investigated. Fe₃O₄ nanoparticles were prepared by coprecipitation method. Further condensation reaction was used to fabricate the double‐layer lauric acid modified Fe₃O₄ (DLF) nanoparticles dispersed well in water. Thermal properties of poly(N‐isopropylacrylamide) (PNIPAAm) and DLF/PNIPAAm composites and their aqueous solutions were measured by TGA and DSC. With the increasing of DLF content, the interaction between DLF and PNIPAAm caused the lower critical solution temperature (LCST) of polymer solution to shift from 33 to 31.25 °C. The effects of concentration and pH on LCST were also studied. The DLF/PNIPAAm nanofibers were fabricated by electrospinning. Their diameters were around 100–250 nm. Magnetization curves of DLF/PNIPAAm composite and nanofibers were overlapped and the saturated magnetizations were the same. Magnetic attraction behaviors of DLF/PNIPAAm polymer solution at temperatures below and above LCST were different. Aggregation of DLF/PNIPAAm above LCST enhanced magnetic moment density as well as magnetic attraction ability. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 848–856     

Biocompatible and biodegradable polymer nanofibers displaying superparamagnetic properties.

Superparamagnetic polymer nanofibers intended for drug delivery and therapy are considered here. Magnetite (Fe3O4) nanoparticles in the diameter range of 5-10 nm were synthesized in aqueous solution. Polymer nanofibers containing magnetite nanoparticles were prepared from commercially available poly(hydroxyethyl methacrylate), PHEMA, and poly-L-lactide (PLLA) by the electrospinning technique. Nanofibers with diameters ranging from 50 to 300 nm were obtained. Nanofibers containing up to 35 wt % magnetite nanoparticles displayed superparamagnetism at room temperature. The blocking temperature was about 50 K for an applied field of 500 Oe, and the saturation magnetization was 3.5 emu g(-1) and 1.1 emu g(-1) for Fe3O4/PHEMA and Fe3O4/PLLA nanofibers, respectively, and depended on the amount of Fe3O4 nanoparticles in the nanocomposites. To test such magnetic nano-objects for applications as drug carriers and drug-release systems we incorporated a fluorescent albumin with dog fluorescein isothiocyanate (ADFI).