Methyltriethoxysilane-derived sol-gel coatings doped with silver metal particles

Silica sol-gel films were prepared by dipping, starting from an acid catalyzed solution of methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS). Silver metal nanoparticles were produced in the silica layer by introducing in the sol-gel precursor solution AgNO₃ or AgClO₄·H₂O. The silver ions were thermally reduced in air at 800°C, giving an intense yellow coating film. The silver metal particles were observed by transmission electron microscopy and X-ray diffraction. The diameter of the silver particles was found to be about 10 nm. Absorption measurements in the UV-Vis were used to evaluate the volume fraction of silver colloids embedded in the silica layer.     

Epitaxial Growth of Sr x Ba1 − x Nb2O6 Thin Films Prepared from Sol-Gel Process

In this study, we prepared Sr _x Ba_{1 – x} Nb₂O₆ (x = 0.3, 0.5 and 0.7) thin film on 0.75 wt% La doped SrTiO₃ (100) and (110) single crystal substrates. A homogeneous coating solution was prepared with Sr and Ba acetates and Nb(OEt)₅ as raw materials, and acetic acid and diethlene glycol monomethyl ether as solvents. The substrates were coated with the solution by spin coating method. As-coated thin films were heated from 973 to 1273 K in air. The grains of the thin film on La doped SrTiO₃ (100) were pillar shaped and arranged in right angle to each other. On the other hand, the grains of these thin films on La doped SrTiO₃ were pillar shape and arranged in one direction. The crystallographic relationship of the thin film between Sr _x Ba_{1 – x} Nb₂O₆ and substrate that the 130 and 310 direction of the thin film on the substrate were oriented with c-axis in parallel to the substrate surface. On the other hand, (hk0) phase diffractions of Sr _x Ba_{1 – x} Nb₂O₆ thin film on the substrate (110) were investigated in the XRD theta-2theta measurement. It is expected that the Sr _x Ba_{1 – x} Nb₂O₆ (x = 0.3, 0.5 and 0.7) were highly oriented or epitaxial growing on La doped SrTiO₃ (110) single crystal substrate.     

Structural colors in nature: the role of regularity and irregularity in the structure.

Coloring in nature mostly comes from the inherent colors of materials, but it sometimes has a purely physical origin, such as diffraction or interference of light. The latter, called structural color or iridescence, has long been a problem of scientific interest. Recently, structural colors have attracted great interest because their applications have been rapidly progressing in many fields related to vision, such as the paint, automobile, cosmetics, and textile industries. As the research progresses, however, it has become clear that these colors are due to the presence of surprisingly minute microstructures, which are hardly attainable even by ultramodern nanotechnology. Fundamentally, most of the structural colors originate from basic optical processes represented by thin-film interference, multilayer interference, a diffraction grating effect, photonic crystals, light scattering, and so on. However, to enhance the perception of the eyes, natural creatures have produced various designs, in the course of evolution, to fulfill simultaneously high reflectivity in a specific wavelength range and the generation of diffusive light in a wide angular range. At a glance, these two characteristics seem to contradict each other in the usual optical sense, but these seemingly conflicting requirements are realized by combining appropriate amounts of regularity and irregularity of the structure. In this Review, we first explain the fundamental optical properties underlying the structural colors, and then survey these mysteries of nature from the viewpoint of regularity and irregularity of the structure. Finally, we propose a general principle of structural colors based on structural hierarchy and show their up-to-date applications.     

Surface structure of thin asymmetric PS-b-PMMA diblock copolymers investigated by atomic force microscopy

Asymmetric poly(styrene-b-methyl methacrylate) (PS-b-PMMA) diblock copolymers of molecular weight M_n = 29,700 g mol⁻¹ (M_PS = 9300 g mol⁻¹M_PMMA = 20,100 g mol⁻¹, PD = 1.15, χ_PS = 0.323, χ_PMMA = 0.677) and M_n = 63,900 g mol⁻¹ (M_PS = 50,500 g mol⁻¹, M_PMMA = 13,400 g mol⁻¹, PD = 1.18, χ_PS = 0.790, χ_PMMA = 0.210) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Atomic force microscopy (AFM) was used to investigate the surface structure of thin films, prepared by spin-coating the diblock copolymers on a silicon substrate. We show that the nanostructure of the diblock copolymer depends on the molecular weight and volume fraction of the diblock copolymers. We observed a perpendicular lamellar structure for the high molar mass sample and a hexagonal-packed cylindrical patterning for the lower molar mass one. Small-angle X-ray scattering investigation of these samples without annealing did not reveal any ordered structure. Annealing of PS-b-PMMA samples at 160 °C for 24 h led to a change in surface structure.     

Mechanical behaviour of biodegradable agricultural films under real field conditions

The mechanical behaviour of various types of biodegradable materials depends on their chemical composition and additives, the processing characteristics and the application conditions. The environmental conditions during storage and usage of these materials strongly influence their mechanical properties and behaviour. Ageing and degradation during the useful lifetime of biodegradable agricultural films causes losses in the mechanical performance of the material, as measured by monitoring the evolution of some of the critical mechanical properties. Such losses may be comparable to the corresponding losses of the conventional polyethylene agricultural films due to ageing, or they may be more drastic. In the present paper, the overall mechanical and ageing/degradation behaviour of experimental specially designed and manufactured low-tunnel and mulching biodegradable films, exposed to full-scale field conditions is analysed. Selected critical mechanical properties of these films manufactured with different grades of Mater-Bi material and additives, different thickness and processing schemes and exposed to real cultivation conditions in four different locations in Europe are investigated in the laboratory and compared against the corresponding behaviour of conventional agricultural films at various stages of their exposure time.     

BARRIER PROPERTIES OF VINYLIDENE CHLORIDE/METHYL ACRYLATE COPOLYMER

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) ascomonomer (3--12wt%), was prepared by free-radical suspension copolymerization. Thepermeability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor were measured at 30℃ and 100% relativehumidity All the VDC/MA copolymers studied are semicrystalline. As the MA contentincreases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, andwater vapor are progressively increased, caused by decrease in crystalline fraction andincrease in free volume of VDC/MA copolymers.     

Thermoanalytical methods in the study of inorganic thin films

Thermoanalytical (TA) methods are relatively seldom applied for assessing the physical and chemical proeprties of thin films, but they can be used in studies of composition, phase transitions and film—substrate interactions. In the present paper the possibilities of TA methods in thin film studies are reviewed. The thermoanalytical methods considered are the classical TG and DTA/DSC methods but some complementary methods will also be briefly mentioned. The main emphasis is given to true thin films. Details of sample preparation are also given. An important application of TA methods is characterization of precursors for the CVD growth of thin films, and this is also discussed.     

DC-plasma polymerization of pyrrole

DC-plasma-polymerized pyrrole (PP-Py) films deposited on metals were extensively characterized by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), Reflection-Absorption IR Spectroscopy (RAIR), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM), Glow Discharge Optical Spectroscopy (GDOS), electrical conductivity (ASTM Franklin test), and contact angle measurements. TOF-SIMS and RAIR showed no spectroscopic evidence of the presence of the pyrrole ring structure in any of the plasmadeposited films. The major parameter that affected their composition was found to be the pressure. Films deposited at low pressure were less hydrogenated than those polymerized at high pressure or in remote plasma conditions. Although all deposits oxidized slowly in air, their surface energy remained low over an extended period of time. The electrical conductivity of the PP-Py films was in the range of 10⁻³–10⁻⁴ S/cm, i.e., higher than that of amorphous carbon films.     

Fluorinated compounds for advanced IC interconnect applications: a survey of chemistries and processes

The semiconductor industry is now in the early stages of an unprecedented change in materials set for the integrated circuit (IC) interconnect structure. The traditional layers of aluminum conductors and silicon dioxide dielectrics are being replaced by copper thin films and a variety of low k candidates, respectively. In many cases, fluorine confers desirable properties on either the precursors or the final films. At the same time, fluorine presents some potentially adverse effects, which have led to a so-called “fear-of-fluorine” in interconnect applications. This paper will review the proposed uses of fluorinated compounds in the interconnect structures, covering both precursors and the resulting thin films. Both the status of technical studies, and the prospects for commercial implementation, will be addressed.