共查询到20条相似文献,搜索用时 15 毫秒
1.
Pratima Parashar 《Journal of Materials Science: Materials in Electronics》2012,23(6):1169-1173
Results of the structural studies of silver particulate films deposited at a rate of 0.4 nm/s on polymeric blends of polystyrene/poly
(2-vinyl pyridine), PS/P2VP held at a temperature 457 K by evaporation in a vacuum of 8 × 10−6 Torr are reported here. The morphology of silver particulate films, characterized by their size, size distribution, shape
and inter-particle separation, was observed to modify due to blending of PS with P2VP and amount of silver deposited. The
red shift in the plasmon resonance indicates the effect of blending P2VP with PS. Scanning electron microscopy was used to
study the change in morphology of the silver nanoparticles in correlation with the optical properties of silver particulate
films on PS/P2VP blends. The silver nanoparticles on the thin layers of polymer blends exhibited much smaller, narrower dispersion
and wide size distribution due to blending of PS with P2VP. 相似文献
2.
A facile synthesis of silver nanoparticles (with a diameter of 5 nm)/polymer hybrid films was studied through auto-reduction of silver nitrate (AgNO3) in poly(1H,1H-dihydroperfluorooctyl methacrylate-b-ethylene oxide) (poly(FOMA(10k)-b-EO(10k micellar thin films at ambient temperature. Silver nanoparticles well dispersed in the block copolymeric micellar films were prepared by rendering the silver precursor AgNO3 to interact favorably with PEO blocks. With annealing of the micellar film containing AgNO3 in supercritical CO2, the domains and continuous phase of the micellar film morphology were inverted and silver nanoparticles with a diameter of 10 nm were produced in PEO domains. The synthesis of silver nanoparticles in the copolymeric films was confirmed by transmission electron microscope and UV-visible spectrophotometric analysis. 相似文献
3.
Choi JH Jung CH Hwang IT An MY Lee BM Kim DK Lee JS Nho YC Huh KM Hong SK 《Journal of nanoscience and nanotechnology》2010,10(10):6879-6882
A convenient and effective method to pattern polymer-embedded metal nanoparticles by ion irradiation has been developed. The thin Pluronic films containing silver nitrate as a precursor of silver nanoparticles were irradiated through a pattern mask with accelerated proton (H+) ions. It was found from the UV-Vis measurement that the formation of silver nanoparticles in the Pluronic matrix was dependant on the amount of silver nitrate. The 50 microm line (pitch 150 microm) patterns of the Pluronic containing silver nanoparticles were obtained with the thin film irradiated to 1 x 10(16) ions/cm2. The heat treatment effect on the morphology of the patterns was investigated by using a scanning electron microscope with an energy dispersive X-ray spectrometer. The results confirmed that the silver nanoparticles were successfully embedded in the Pluronic patterns and the patterns were changed into large silver particles by a heat treatment above 350 degrees C. 相似文献
4.
5.
A photocatalytic thin film of TiO? nanoparticles and polyaniline-grafted-chitosan (CPANI) was fabricated by layer-by-layer (LbL) approach. The growth of the self-assembly of polymer nanocomposite was monitored by UV-vis spectroscopy and the thin film morphology was analyzed from scanning electron microscopy (SEM). Poly(styrene sulfonate) (PSS) was used as a bridging layer between TiO? nanoparticles and CPANI. Incorporation of CPANI within the LbL self-assembly of polymer nanocomposites enhanced the dye degradation ability of the thin film. These results indicate that the presence of CPANI improves the adsorption of dye in the self-assembly. The effect of surface area and the amount of catalyst was also examined. The reusability of the thin films for dye degradation study ensures the stability of the self-assembly. 相似文献
6.
Murali Sastry 《Bulletin of Materials Science》2000,23(3):159-163
Ellipsometry is currently one of the most important techniques for characterization of the deposition and growth mode of ultra
thin organic films. However, it is well known that for thicknesses normally encountered in organic monolayer films, as would
occur for example in self-assembled monolayers, ellipsometry cannot be used to simultaneously determine the thickness and
refractive index of the monolayer film. Current practice is to assume a reasonable value for the film refractive index and
calculate an effective ‘ellipsometric thickness’. This communication seeks to show that the alternative approach of assuming
a thickness for the monolayer (determined by the length of the molecule) and calculating the effective film refractive index
lends itself to easier and more meaningful physical interpretation. The Lorentz-Lorenz formula is then used to transform the
effective refractive index into a surface coverage and hence to an effective mass coverage. The methodology advanced is applied
to the kinetics of formation of a self-assembled monolayer of a well-studied molecule, octadecanethiol on Au. 相似文献
7.
聚合物基底上纳米银颗粒薄膜的制备工艺相对简单,成本较低,且该薄膜具有成为高敏感性压阻应力/应变传感材料的潜力。本文采用银镜制备法在聚酰亚胺(PI)和聚乙烯(PE)上合成了纳米银颗粒薄膜,系统研究了该薄膜制备工艺、结构特性、材料性能之间的关系。实验考察了材料“浸泡”时间及聚合物材料前处理等因素对材料表面吸附纳米颗粒含量的影响,研究了 “浸泡”时间对纳米银颗粒粒径大小、颗粒含量及分布的影响,并探讨了不同聚合物基体的颗粒特性对薄膜二维导电渗滤,压阻特性及拉伸性能的影响。研究表明,增加“浸泡”时间能够增加纳米银颗粒粒径大小,提高银颗粒的含量及分布均匀性;在相同的制备条件下,PI基底较PE基底对纳米银颗粒具有更加优异的吸附效果;在PI 和PE基底上的纳米银颗粒薄膜均表现出显著的压阻性能,且电阻对应变的敏感性随应变的增大及银颗粒含量的减少而显著提高。 相似文献
8.
Martin Drábik Josef Pe?i?ka Hynek Biederman Dirk Hegemann 《Science and Technology of Advanced Materials》2015,16(2)
Nanocomposite coatings of silver particles embedded in a plasma polymer matrix possess interesting properties depending on their microstructure. The film microstructure is affected among others also by the RF power supplied during the deposition, as shown by transmission electron microscopy. The optical properties are characterized by UV–vis–NIR spectroscopy. An anomalous optical absorption peak from the Ag nanoparticles is observed and related to the microstructure of the nanocomposite films. Furthermore, a long-term aging of the coatings is studied in-depth in ambient air and in aqueous environments. It is shown that the studied films are not entirely stable. The deposition conditions and the microstructure of the films affect the processes taking place during their aging in both environments. 相似文献
9.
Porel S Venkatram N Rao DN Radhakrishnan TP 《Journal of nanoscience and nanotechnology》2007,7(6):1887-1892
We present an overview of the simple and environmentally benign protocol we have developed recently, for the in situ generation of metal nanoparticles inside polymer films by mild thermal annealing, leading to free-standing as well as supported thin films of nanoparticle-embedded polymer. The fabrication chemistry is discussed and spectroscopic/microscopic characterizations of silver and gold nanoparticles in poly(vinyl alcohol) film are presented. Optical limiting characteristics of the silver-polymer system are investigated in detail and preliminary results for the gold-polymer system are reported. 相似文献
10.
AbstractNanocomposite coatings of silver particles embedded in a plasma polymer matrix possess interesting properties depending on their microstructure. The film microstructure is affected among others also by the RF power supplied during the deposition, as shown by transmission electron microscopy. The optical properties are characterized by UV–vis–NIR spectroscopy. An anomalous optical absorption peak from the Ag nanoparticles is observed and related to the microstructure of the nanocomposite films. Furthermore, a long-term aging of the coatings is studied in-depth in ambient air and in aqueous environments. It is shown that the studied films are not entirely stable. The deposition conditions and the microstructure of the films affect the processes taking place during their aging in both environments. 相似文献
11.
Microstructure and optical properties of plasmapolymer thin films with embedded silver nanoparticles
A. Heilmann J. Werner D. Schwarzenberg S. Henkel P. Grosse W. Thei 《Thin solid films》1995,270(1-2):103-108
Plasmapolymer thin films with embedded silver nanoparticles were deposited by simultaneous plasma polymerization and metal evaporation. The particle size and shape were determined by transmission electron microscopy (TEM) and analysed by optical image processing. The optical properties in the UV/ VIS/NIR spectral region were determined by the plasma resonance absorption of the silver particles. Transmittance spectra were calculated with the Bergman effective medium theory and compared with experimental spectra. 相似文献
12.
Transmission electron microscopy was used to determine the structure of molecular films of self-assembled monolayers of pentathiophene derivatives supported on various electron transparent substrates. Despite the extreme beam sensitivity of the monolayers, structural crystallographic maps were obtained that revealed the nanoscale structure of the film. The image resolution is determined by the minimum beam diameter that the radiation hardness of the monolayer can support, which in our case is about 90 nm for a beam current of 5 × 10(6) e(-)/s. Electron diffraction patterns were collected while scanning a parallel electron beam over the film. These maps contain uncompromised information of the size, symmetry and orientation of the unit cell, orientation and structure of the domains, degree of crystallinity, and their variation on the micrometer scale, which are crucial to understand the electrical transport properties of the organic films. This information allowed us to track small changes in the unit cell size driven by the chemical modification of the support film. 相似文献
13.
Diamond-like carbon (DLC) film as a solid lubricant coating represents an important area of investigation related to space devices. The environment for such devices involves high vacuum and high concentration of atomic oxygen. The purpose of this paper is to study the behavior of silver-incorporated DLC thin films against oxygen plasma etching. Silver nanoparticles were produced through an electrochemical process and incorporated into DLC bulk during the deposition process using plasma enhanced chemical vapor deposition technique. The presence of silver does not affect significantly DLC quality and reduces by more than 50% the oxygen plasma etching. Our results demonstrated that silver nanoparticles protect DLC films against etching process, which may increase their lifetime in low earth orbit environment. 相似文献
14.
The surface morphology in thin films of immiscible polyetherimide and polycaprolactone blends was studied using scanning electron and atomic force microscopy. The thin films were obtained by spin-coating from dichloromethane solution. A self-assembled periodic pattern of phase separated domains was observed, which was induced by capillary effects along with the solution radial flow and the unsteady air flow field above the film during the initial stages of spin-coating. A secondary phase separation was observed during the solvent evaporation stage of spin-coating. The differences in surface topographies of the two distinct phases are attributed to different solvent evaporation rates within each phase. In addition, a great variety of domain structures and surface morphologies were observed as a function of polymer blend composition. 相似文献
15.
采用自组装单层膜技术在玻璃基板上成功制备了钛酸锶薄膜,利用接触角仪对前期处理后的基片润湿角进行表征,利用X射线衍射(XRD),扫描电镜(SEM)等手段表征了薄膜的物相和微观结构。实验结果表明:采用自组装单层膜技术制备的钛酸锶薄膜结晶良好,样品表面均匀,颗粒尺寸大约在300nm~500nm之间。 相似文献
16.
在室温条件下采用射频磁控溅射在丙纶(PP)、聚乳酸(PLA)熔喷非织造布表面生长纳米银(Ag)薄膜,并且用等离子体预处理样品进行对比。采用扫描电子显微镜(SEM)对其形貌进行表征,采用四探针测试仪对所制备的纳米薄膜的导电性能进行表征。研究溅射时间、孔隙率及孔径分布和等离子处理对非织造基纳米银薄膜的导电性能的影响。实验表明:随着反应溅射时间的增加,薄膜的方块电阻值下降,导电性能增加;孔径大小也影响薄膜的导电性能,随着孔径的增大,薄膜的导电性能降低;等离子体处理对织物表面进行刻蚀,增加了纤维的比表面积,提高了纤维的润湿性能,改善了织物的导电性能。 相似文献
17.
Composite films containing heparin and hydroxyapatite in a polypyrrole (PPY) matrix were electrochemically deposited as monolayers or bi-layers on conductive substrates. The deposition on stainless steel substrates was achieved using a thin prime layer of PPY deposited by anodic electropolymerization in the presence of salicylate anions, which passivated the substrate surface. The deposition mechanism, film composition and morphology were investigated. The films containing heparin may have improved anticoagulant activity as suggested by their ability to bind antithrombin from plasma. 相似文献
18.
19.
When a drop of a colloidal solution of nanoparticles dries on a surface, it leaves behind coffee-stain-like rings of material with lace-like patterns or clumps of particles in the interior. These non-uniform mass distributions are manifestations of far-from-equilibrium effects, such as fluid flows and solvent fluctuations during late-stage drying. However, recently a strikingly different drying regime promising highly uniform, long-range-ordered nanocrystal monolayers has been found. Here we make direct, real-time and real-space observations of nanocrystal self-assembly to reveal the mechanism. We show how the morphology of drop-deposited nanoparticle films is controlled by evaporation kinetics and particle interactions with the liquid-air interface. In the presence of an attractive particle-interface interaction, rapid early-stage evaporation dynamically produces a two-dimensional solution of nanoparticles at the liquid-air interface, from which nanoparticle islands nucleate and grow. This self-assembly mechanism produces monolayers with exceptional long-range ordering that are compact over macroscopic areas, despite the far-from-equilibrium evaporation process. This new drop-drying regime is simple, robust and scalable, is insensitive to the substrate material and topography, and has a strong preference for forming monolayer films. As such, it stands out as an excellent candidate for the fabrication of technologically important ultra thin film materials for sensors, optical devices and magnetic storage media. 相似文献
20.
S. G. Pawar S. L. Patil M. A. Chougule B. T. Raut S. A. Pawar R. N. Mulik V. B. Patil 《Journal of Materials Science: Materials in Electronics》2012,23(1):273-279
Nanocrystalline titanium oxide thin films have been deposited by spin coating technique and then have been analyzed to test
their application in NH3 gas-sensing technology. In particular, spectrophotometric and conductivity measurements have been performed in order to determine
the optical and electrical properties of titanium oxide thin films. The structure and the morphology of such material have
been investigated by X ray diffraction, Scanning microscopy, high resolution electron microscopy and selected area electron
diffraction. The X-ray diffraction measurements confirmed that the films grown by this technique have good crystalline tetragonal
mixed anatase and rutile phase structure. The HRTEM image of TiO2 thin film showed grains of about 50–60 nm in size with aggregation of 10–15 nm crystallites. Selected area electron diffraction
pattern shows that the TiO2 films exhibited tetragonal structure. The surface morphology (SEM) of the TiO2 film showed that the nanoparticles are fine with an average grain size of about 50–60 nm. The optical band gap of TiO2 film is 3.26 eV. Gas sensing properties showed that TiO2 films were sensitive as well as fast in responding to NH3. A high sensitivity for ammonia indicates that the TiO2 films are selective for this gas. 相似文献