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简述了当今倍受关注的等离子体聚合薄膜技术和各种等离子体纳米聚合反应装置,讨论了各种纳米材料如氧化锌(ZnO)、碳纳米管(CNT)、碳纳米纤维(CNF)等离子体表面改性结果。     

Synthesis of hollow nanoparticles by plasma polymerization

A capacitively coupled low pressure plasma is used to produce particles by plasma polymerization of various organic precursors. The particles produced by this method are spherical, submicron in diameter, and contain a hollow center. Sixteen organic molecules were tested for the ability to produce hollow particles. Of these, 12 were found to reproducibly result in the formation of hollow particles while the other 4 either produced non-hollow particles or no particles at all under the conditions investigated here. Cyclohexane derivatives and the presence of an aromatic ring correlate strongly with a tendency to form hollow centers. The particle sizes vary from 70 nm to nearly 1 m and the core diameter is on the average 18 of the particle diameter. The corresponding shell thickness ranges from 24 nm for styrene to about 360 nm for cyclohexane. To explain the formation of hollow centers a mechanism is proposed based on the hypothesis that the solid phase is formed via crosslinking and solidification of viscous drop. This mechanism explains the observed linear relationship between core size and particle size.     

ZnO nanoparticles produced by novel reactive physical deposition process

This paper reports the deposition of ZnO nanoparticles with controlled sizes and different particle densities and their structural, composition and optical properties. They were deposited by means of a DC magnetron based vacuum nanoparticle source onto different substrates (GaAs, Si and Ti/SiO₂/Si). We believe that this is the first time that such nanoparticles have been produced using this unique technique. Zinc was used as sputtering target to produce zinc nanoparticles which were oxidized in-line using molecular oxygen. The structural properties and chemistry of the ZnO were studied by transmission electron microscopy. An average particle size of 6(±2) nm was produced with uniform size distribution. The particle density was controlled using a quartz crystal monitor. Surface densities of 2.3 × 10¹¹/cm², 1.1 × 10¹³/cm² and 3.9 × 10¹³/cm² were measured for three different deposition runs. The ZnO particles were found to be single crystalline having hexagonal structure. Photoluminescence measurements of all samples were performed at room temperature using a cw He-Cd laser at 325 nm excitation. The UV emission around 375 nm at room temperature is due to excitonic recombination and the broad emission centered at 520 nm may be attributed to intrinsic point defects such as oxygen interstitials.     

Characterization of bioactive RGD peptide immobilized onto poly(acrylic acid) thin films by plasma polymerization

Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH₂ of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants.     

Surface modification of magnetic metal nanoparticles through irradiation graft polymerization

To tailor the interfacial interaction in magnetic metal nanoparticles filled polymer composites, the surfaces of iron, cobalt and nickel nanoparticles were grafted by irradiation polymerization. In the current report, effects of grafting conditions, including irradiation atmosphere, irradiation dose and monomer concentration, on the grafting reaction are presented. The interaction between the nanoparticles and the grafted polymer was studied by thermal analysis and X-ray photoelectron spectrometry. It was found that there is a strong interfacial interaction in the form of electrostatic bonding in the polymer-grafted nanoparticles. The dispersibility of the modified nanoparticles in chloroform was significantly improved due to the increased hydrophobicity.     

Yellowish-white photoluminescence from ZnO nanoparticles doped with Al and Li

ZnO nanoparticles codoped with Al and Li were chemically synthesized with a low temperature drying process. They are crystalline and can be made as small as 5 nm. Intense yellowish white photoluminescence was observed from smaller ZnO nanoparticles with a higher concentration of Al and Li. The photoluminescence peak consists of yellow and green emission bands. Both peak intensities increase with increasing the Al and Li concentrations and with decreasing the size of ZnO nanoparticles. The green and yellow emission bands were attributed to donor–acceptor-pair recombination involving Zn vacancies and lithium as the acceptor state, respectively, and the donor responsible for both emissions to oxygen vacancies. Both enhanced emissions by codoping may be explained by an increase in the number of electrons occupying the deep donor level on account of doping with Al. Although the yellowish white emission decays with time, passivation of the crystallite surface with poly(p-phenylene vinylene) suppresses the degradation. The observed high-intensity and stable yellowish white emission makes PPV-passivated ZnO nanoparticles, codoped with Al and Li, more attractive as a candidate for “white” phosphor.     

Enhancement of surface morphology and optical properties of nanocolumnar ZnO films

Nanocolumnar ZnO films were prepared by electrodeposition (ED) on a glass substrate covered with a conductive layer of thin oxide doped with fluorine (FTO). After deposition the samples were annealed in oxidizing or reducing atmosphere, at temperatures between 100 to 500 C, in order to follow the evolution of optical properties and morphology. The optical properties of these films were studied by means of photoluminescence spectroscopy (PL) and the morphology by scanning electron microscopy (SEM). Films annealed at 300 C exhibit a higher ultraviolet emission peak, originating from exciton transitions. A green band related to deep-level emission centered at 500 nm, shows a drastic increase at 500 C. These results are independent of the annealing atmosphere. An increase of coalescence is also observed after annealing at 500 C. These results are explained taking into account the contribution of different point defects.     

A study on optical,photoluminescence and thermoluminescence properties of ZnO and Mn doped-ZnO nanocrystalline particles

Pure ZnO and Mn (1%wt.) doped-ZnO nanocrystalline particles were synthesized by reverse micelle method. The structural properties of the nanoparticles were investigated by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. UV–vis and photoluminescence (PL) spectroscopy was used for analyzing the optical properties of the nanoparticles. XRD and TEM results revealed the formation of ZnO and Mn doped-ZnO nanocrystalline particles with pure wurtzite crystal structure and average particle size of 18–21 nm. From UV–vis studies, the optical band gap energy of 3.53 and 3.58 eV obtained for ZnO and Mn doped-ZnO nanoparticles, respectively. Further optical analysis showed that the refractive index decreases from 2.35 to 1.35 with the change of wavelength. Room-temperature photoluminescence analysis of all samples showed four main emission bands including a strong UV emission band, a weak blue band, a week blue–green band, and a weak green band which indicated their high structural and optical quality. Moreover, the samples exposed to gamma rays sources of ¹³⁷Cs and ⁶⁰Co and their thermoluminescence properties were investigated. The thermoluminescence response of ZnO and Mn doped-ZnO nanocrystalline particles as a function of dose exhibited good linear ranges, which make them very promising detectors and dosimeters suitable for ionizing radiation.     

Effect of solution concentrations on crystal structure,surface topographies and photoluminescence properties of ZnO thin films

Zinc oxide thin films were deposited on silicon substrates via hydrothermal method. Microstructures, surface topographies and optical properties of ZnO thin films were systematically investigated by X-ray diffraction, atomic force microscopy and fluorescence spectrophotometer. The mean grain size and surface roughness of the thin films decrease first and then increase with increasing the concentration of zinc nitrate hexahydrate. The photoluminescence spectra of ZnO thin films, excited by the 240, 320, 360, 380 and 400 nm excitation wavelength, were investigated in detail. Based on our analysis, it can be noted that mechanisms of the ultraviolet, violet and blue emissions are attributed to the transitions from the localized levels below the conduction band, zinc vacancy, interstitial zinc and extended interstitial zinc levels to the valance band, respectively. Blue–violet emissions of ZnO have great potential in light emitting and biological fluorescence labeling applications.     

Surface-initiated addition polymerization of norbornene by a Pd(II) catalyst bearing acetylacetone ligand on the glass slide

A Pd catalyst bearing acetylacetone ligand [(CH₃CO)₂CHPdCl₂] was covalently attracted onto the surface of glass slides, and then these Pd-terminated glass slides were immersed into a toluene solution of norbornene (NB) to produce a vinyl-type addition polynorbornene (PNB) layer on the surface of glass slides. It was found that the contract angles of the PNB-terminated glass slides surface increased with the increasing of polymerization time, and the thickness of the PNB layers were approximately 0-44.0 μm when the polymerization time was 0.5-24 h. The researching on etching also has been operated.     

Observation of band gap and surface defects of ZnO nanoparticles synthesized via hydrothermal route at different reaction temperature

The effects of reaction temperature on the average particle size, surface defects and band gap of ZnO nanoparticles have been systematically investigated. The hydrothermal method was employed to synthesize ZnO nanostructures. The nanostructures of the resultant ZnO were studied by means of X-ray diffraction, Transmission Electron Microscopy, Ultraviolet-visible absorption, Raman, Fourier transform Infra-red and Photoluminescence spectroscopy. With increase in the reaction temperature, the peak position of the ultraviolet emission shifts slightly towards the red wavelength and the crystal quality was improved. The prepared ZnO nanoparticles have residual intermediate compound on the surface in the form of an acetate group, which acts as defect centers for the emission of yellow emission. Spectra analyses show that the visible emission depends strongly on the preparation conditions.     

Morphology and photoluminescence study of electrodeposited ZnO films

ZnO films on ITO substrates and Au coated ITO substrates were fabricated by using electrodeposition technique. We carried out the experiments by adjusting the concentration of solution, potential, substrate, and temperature. The effect of temperature on the growth of the film has been examined. SEM images have shown that there are several kinds of grown competitions for the deposition of ZnO films, but three kinds of them are dominant. One is the discrete hexagonal column structure, the other is the pentagonal structure, and the third one is of well-oriented hexagonal columns with well-aligned structure. The explanation on the grown competition is discussed. ZnO hexagonal column structures with well-aligned and well-perpendicular to the surface were successfully obtained on Au/ITO substrate in aqueous solvent of electrolyte. Clearly the main columns in the film were obtained by increasing the temperature. Its photoluminescence (PL) study at low temperature exhibited the optical properties as wurtzite ZnO and indicated the existence of macrocrystalline ZnO. A better quality of ZnO columnar structures after annealing was demonstrated from PL analysis and discussion on the existence of 370 nm, 384 nm and 639 nm in the emission bands before and after annealing.     

The dispersion study of TiO2 nanoparticles surface modified through plasma polymerization

In this study, the surface of TiO₂ nanoparticles was modified through plasma polymerization, which is a dry coating method at room temperature. The surface morphology of TiO₂ nanoparticles was characterized by high-resolution transmission electron microscope (HRTEM). The dispersion behavior of TiO₂ nanoparticles in water and ethyl glycol was investigated by laser size distribution and ultraviolet–visible absorption spectrum. TiO₂ nanoparticles were coated with a thin film through plasma polymerization, which prevents the agglomeration and improves the dispersion behavior of TiO₂ nanoparticles.     

Synthesis and photoluminescence properties of ZnO nanorods and nanotubes

Different morphologies of zinc oxide (ZnO) nanorods and nanotubes, which were grown under the same conditions but different dissolving processes, are prepared in our experiment through hydrothermal method. After the growth process, cooling down the reactor naturally or dissolving at a constant temperature of 40 °C, preferential dissolution will occur at different places on the tip of ZnO nanorods. During the dissolution process, different dissolution rates on the entire surface of nanorod will lead to different nanostructures. ZnO nanorods and nanotubes on Cu substrates display the same PL property with strong green emission but weak UV emission, while ZnO nanorods on Si substrates exhibits a relatively strong UV emission.     

Preparation and photoluminescence of Sc-doped ZnO nanowires

We demonstrate bulk synthesis of single-crystal Sc-doped ZnO nanowires by using (Sc+Zn) powders at . These mass nanowires are characterized through X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction, and high-resolution TEM, which have uniform diameters of about 40 nm and microns of several decades in length. The growth of ZnScO nanowires is suggested for self-catalyzed vapor–liquid–solid. In particular, PL spectra of these nanowires show emission peaks that intensely shift to long wavelength with increasing Sc and the doping quantity is found responsible for the different characteristics, in which PL mechanism is explained in detail.     

Fabrication of zinc oxide nano-structures in RF inductively-coupled thermal plasma and their photoluminescence effects

Zinc oxide (ZnO) nanoparticles and nano-structures were synthesized using RF inductively-coupled thermal plasma system. The ZnO nanoparticles synthesized in high enthalpy plasmas showed high purity and extremely small crystalline characteristics with the (30–50) nm size distribution applicable in various areas. The resultant morphology of the ZnO nanoparticles was influenced by process parameters such as chamber pressure, a cooling method and a reactor configuration. Thus, the effects of process conditions were discussed with perspective of the re-crystallization. In addition, by controlling the operational parameters, flower-like shaped ZnO nano-structures consisting of many hexagonal nano-rods with six facets were also obtained. The ZnO nano-structures showed a good optical property in photoluminescence analysis.     

Surface tailoring of SiO2 nanoparticles by mechanochemical method based on simple milling

An appropriate modifying agent is obviously important with regard to the surface treatment of nanoparticles. Moreover, a right physical mixer that can provide enough energy to break up the secondary structure (aggregate and agglomerate) of nanoparticles is absolutely critical to the modification as well. However, it is not easy to give consideration to both of them during the process of modification. As is often the case, we tend to take care of the modifying agent but lose sight of the physical mixer. In this paper, hybrid particles of SiO₂/2,4-Diisocyanatotoluene (SiO₂/TDI) and SiO₂/2,4-Diisocyanatotoluene/hydroxyl silicone oil (SiO₂/TDI/(PDMS-OH)) were fabricated by mechanochemical method based on simple milling. The prepared hybrid particles (SiO₂/TDI and SiO₂/TDI/(PDMS-OH)) were characterized by infrared spectroscopy (FT-IR), static contact angle (CA), water sorption measurement, thermal analysis (TGA and DSC) and transmission electron microscopy (TEM). FT-IR spectra and thermal analysis (DSC) results demonstrate that TDI together with PDMS-OH is chemically anchored to the surface of nano-SiO₂. TGA results show that the grafting density of TDI is as high as 2.62 TDI/nm², while the grafting density of PDMS-OH is 0.0156 PDMS-OH/nm². Deduced from static contact angle (CA) and water sorption measurement, both hybrid particles exhibit strong hydrophobic (140^o for SiO₂/TDI and 144^o for SiO₂/TDI/(PDMS-OH)) after modification. TEM images reveal that hybrid particles (SiO₂/TDI and SiO₂/TDI/(PDMS-OH)) prepared by ball milling method exhibit much better miscibility and dispersibility in PDMS matrix when compared with those particles prepared by a common mixing device.     

Fabrication and photoluminescence of P doped ZnO nanobelts by thermal evaporation method

Uniform and flat single crystal ZnO:P nanobelts (NBs) were fabricated on Si (1 0 0) substrates by the thermal evaporation method. The growth process, free-catalyst self-assembly vapor-solid (V-S) mechanism, was described and investigated deeply in terms of thermodynamics and kinetics. Then, the photoluminescence (PL) properties of ZnO NBs were studied in a temperature range from 10 to 270 K. At 10 K the recombination of acceptor-bound exciton (A⁰X) was predominant in the PL spectrum, and was attributed to the transition of P_Zn−2V_Zn complex bound exciton. The active energy of A⁰X and acceptor binding energy were calculated to be 17.2 and 172 meV, respectively. The calculated acceptor binding energy of P doped ZnO nanostructure is in good agreement with that of P doped ZnO film.     

Microstructure and photoluminescence of MoOx decorated ZnO nanorods

Various MoO_x decorated ZnO nanorods (ZnO-MoO_x) samples were fabricated by physical vapor deposition of MoO_x on the surface of ZnO nanorods with varying deposition time and temperature. The microstructure and photoluminescence (PL) of the ZnO-MoO_x samples were investigated. It was found that the morphology of the ZnO nanorods is changed from hexagonal prisms to lotus-roots-like shapes by the decoration of MoO_x. The lotus-roots-like shapes may be formed by partial melting and evaporating of ZnO-MoO_x during the MoO_x decoration. This result shows that one can use the thermal instability of a nano-material to obtain an interesting structure, although a thermal instability should often be avoided. The intensity of the ultraviolet and visible light emission the of ZnO nanorods have different dependencies on the MoO_x decoration. Although the position of the ultraviolet light emission is not obviously changed by the MoO_x decoration, the ultraviolet light emission intensity is greatly weakened. In contrast, the intensity and position of visible light emission is largely changed. The blue shift of the visible light emission might be related to defects introduced by melting of the ZnO nanorods.     

Enhanced blue photoluminescence and new crystallinity of Ag/organic rubrene core-shell nanoparticles through hydrothermal treatment

Light-emitting organic semiconductors have attracted considerable attention for the nanoscale fabrication of organic-based displays and their potential application in optoelectronics, plasmonics, and photonics. In this study, core-shell hybrid nanostructures of organic rubrene coated on Ag nanoparticles (NPs) have been synthesized using a chemical reduction method. The thickness of the rubrene shell was 2.6–6.0 nm and the diameter of the Ag core was 30–70 nm. The optical and structural properties of the Ag/rubrene core-shell NPs were tuned by hydrothermal (HT) treatment at 190 °C. The Ag/rubrene core-shell NPs were characterized by high-resolution transmission electron microscopy and energy-dispersive X-ray (EDX) spectroscopy before and after the HT treatment, and their structural properties were confirmed through X-ray diffraction (XRD) analysis. XRD peaks related to an orthorhombic phase were observed along with the original triclinic crystal structure of the rubrene shell, and the triclinic crystal domain size increased from 28.2 nm to 30.8 nm owing to the HT treatment. Interestingly, the green light emission (λ_em = 550 nm) of the Ag/rubrene core-shell NPs changed to blue light emission (λ_em = 425 nm), increasing in intensity through the HT treatment. This is caused by the crystal change with H-type aggregation and enhanced energy transfer from a surface plasmon resonance.