Layered composite films

Ingersoll, D., Kulesza, P.J., and Faulkner, L.R. 1994. Polyoxometallate-based layered composite films on electrodes. Preparation through alternate immersions in modification solutions. Journal of the Electrochemical Society 141, 140-147. 

Layered composite films can be directly prepared by alternate deposition or vacuum filtration of the mixed dispersions of both components. For instance, PANl/Prussian blue composite films have been fabricated using layer-by-layer assembly of the polycation PANI and a negatively ionized Prussian blue nanoparticle dispersion (DeLongchamp and Hammond, 2004). The resultant organic/inorganic nanocomposites exhibited good smoothness and a classical linear increase in film thickness with assembly steps. In... 

However, EVAL as a monolithic film is quite unsatisfactoiy what is required, idealfy, is a multi-layer, composite film. One excellent composite, for example, is a five-layer fihn ABCBA in which A is branched potyethy-lene (35 /tm), B is a binding pofymer (5 /ttm), and C is EVAL (8 to 12 fim). Another barrier component widely used is rylon for example, for a wide range of food packaging a typical combination is ABCBD, in which A is branched polyet lene, B is bonding pofymer, C is nylon 6, and D is... 

Han, G.Y., and G.Q. Shi. 2004. Gonducting polymer electrochemical actuator made of high-strength three-layered composite films of polythiophene and polypyrrole. Sensor Actuator B-Chem 99 525. 

Alloy films may he deposited using multiple sources with individual deposition rate controllers. In this case the vapor flux distribution from each source must he taken into account. The multiple source technique can also be used to deposit layered composite films. Multiple sources with overlapping flux distributions can be used to form films having a range of compositions over the substrate surface. 

Another interesting method, first reported by Mamedov " and later refined by others, is the LBL assembly method. This involves building up a layered composite film by alternate dipping of a substrate into dispersions of SWNTs and polyelectrolyte... 

In multiple-layer thin films, it is possible that some of the elements may be present simultaneously in two or more layers. XRF analysis of this type of film can be complicated and cannot be made solely from their observed intensities. Additional information, such as the compositions or thickness of some of the layers is needed. The amount of addidonal non-XRF information required depends on the complexity of the film. For example, in the analysis of a FeMn/NiFe double-layer film, the additional information needed can be the composition or thickness of either the FeMn or NiFe layer. Using the composition or thickness of one of the film predetermined from a single-layer film deposited under identical condidons, XRF analysis of the FeMn/NiFe film was successfiil. ... 

Narrow composition distribution Absence of high comonomer fraction ease processesing and comonomer effective in reducing m.p. sharp m.p. Heat seal layers in composites films... 

Colour formers such as compounds 243 and 245 are not inherently thermochromic. For example, they melt without any change in colour. However, they may be used to generate colour thermally, either irreversibly or reversibly, as composite materials. In thermally sensitive paper, the colour former and an acidic developer, usually a phenol, are dispersed as insoluble particles in a layer of film-forming material. When brought into contact with a thermal head at around 80-120 °C, the composite... 

Films and sheets are defined as planar flat materials that are self-supporting and flexible. Generally films have a thickness of less than 250 pm, above this thickness they are referred to as sheets. They may consist of one or more layers, usually of different compositions. Films or sheets can be used alone or co-extruded with paper, foil or fabrics. 

Another possible solution to the problem of analyzing multiple-layered membrane composites is a newly developed method using NMR spin-lattice relaxation measurements (Glaves 1989). In this method, which allows a wide range of pore sizes to be studied (from less than 1 nm to greater than 10 microns), the moisture content of the composite membrane is controlled so that the fine pores in the membrane film of a two-layered composite are saturated with water, but only a small quantity of adsorbed water is present in the large pores of the support. It has been found that the spin-lattice relaxation decay time of a fluid (such as water) in a pore is shorter than that for the same fluid in the bulk. From the relaxation data the pore volume distribution can be calculated. Thus, the NMR spin-lattice relaxation data of a properly prepared membrane composite sample can be used to derive the pore size distribution that conventional pore structure analysis techniques... 

Owing to these characteristics, PG has been extensively used for the adsorption of DNA and its derivatives. DNA was successfully adsorbed on PG by dry-adsorption at 100 °C [67]. The electrodes were stored in TriS buffer at 4 °C without loss of DNA, showing that DNA was firmly adsorbed on PG. It was demonstrated that the adsorbed ODN was also able to be hybridized with its complementary strand, suggesting that although DNA bases are compromised in the adsorption, they are still available for hybridization [67]. A composite film of DNA and the polyanionic perfluorosulfonated ionomer Nation was cast on PG by the layer-by-layer procedure performed by dry-adsorption [68]. In another approach, the PG surface was electrochemically pretreated at - 1.7 V for 60 s. DNA was then wet-adsorbed at the pretreated electrode surface from solutions containing 0.2 M NaCl, 10 mM Tris- HCl, pH 7.4, for 1 min followed by rinsing the electrode with distilled water [69,70]. 

Title Copolymer, Organic Insulating Layer Composition, and Organic Insulating Layer and Organic Thin-Film Transistor Manufactured Using the Same... 

This so-called "active" layer has characteristics similar to those of cellulose acetate films but with a thickness of the order of 0.1 micrometer (jjm) or less, whereas the total membrane thickness may range from approximately 75 to 125 ym (see Figure 1). The major portion of the membrane is an open-pore sponge-like support structure through which the gases flow without restriction. The permeability and selectivity characteristics of these asymmetric membranes are functions of casting solution composition, film casting conditions and post-treatment, and are relatively independent of total membrane thickness. 

This chapter concerns composite films prepared by physical vapor deposition (PVD) method. These films consist of dielectric matrix containing metal or semiconductor (M/SC) nanoparticles. The structure of films is considered depending on their formation by deposition of M/SC onto dielectric substrates as well as by layer-by-layer or simultaneous deposition of M/SC and dielectric vapor. Data on mean size, size distribution, and arrangement of M/SC nanoparticles in so obtained different composite films are given and discussed in relation to M/SC nature and matrix properties. Some models of nucleation and growth of M/SC nanoparticles by the diffusion of M/SC atoms/molecules over a surface or in volume of dielectric matrix are proposed and analyzed in connection with experimental data. 

This chapter concerns two types of nanocomposite films M/SC dielectric (a) composite films produced by the vapor deposition of M/SC onto a surface of dielectric substrate or by layer-by-layer deposition of M/SC and dielectric on a substrate, (b) composite films formed as a result of simultaneous deposition of M/SC and dielectric. 

For synthesis of composite films with M/SC nanoparticles distributed in the volume of a dielectric matrix, method PVD is used as co-deposition of M/ SC and dielectric material vapors. A comparison of films produced by codeposition and layer-by-layer deposition PVD methods has been made on the example of BN-Fe nanocomposite films [57]. Unlike the above considered film from alternating layers of Fe and BN, which has ordered structure, co-deposited BN-Fe nanocomposite films consist of amorphous completely disorder matrix BN containing a chaotic system of immobilized Fe nanoparticles. At the same time, these particles in contrast to those of layered film have much smaller size (d — 2.3 nm) since in this case the metal atoms are inside a matrix which slowdowns the diffusion process of atoms aggregation. 

Additional improvements can be achieved through the use of multilayers (based on different overlaid films). Such combination of the properties of different films has been documented with bilayers of Nation/CA (14) and Nafion/collagen (29). The former allows selective measurements of the neurotransmitter dopamine in the presence of the slightly larger epinephrine and the anionic ascorbic acid (Figure 5). In addition to bilayers, mixed (composite) films, such as PVP/CA (75) or polypyrrole/Eastman Kodak AQ (30) layers can offer additional permselectivity advantages, such composites exhibit properties superior to those of their individual components. Also promising are sensor arrays, based on electrodes coated with... 

When a fluid is present in contact with each solid wall, there will be an additional resistance to heat transfer in each fluid boundary layer or film . The combined mechanism of heat transfer from a hot fluid through a dividing wall to a cold fluid has many similarities to conduction through a composite slab reviewed earlier. 

The analysis of several pure metals and binary alloys yields generally at least a duplex and in some cases a multilayer structure of the passive film, as depicted schematically in Fig. 19. These systems have been examined with surface analytical methods, mainly XPS, but also ISS in some cases. The systematic variation of the electrochemical preparation parameters gives insight to the related changes of layer composition and layer development, and support a reliable interpretation of the results. Usually the lower valent species are found in the inner part and the higher valent species in the outer part of the passive layer. It is a consequence of the applied potential which of the species is dominating. Higher valent species are formed at sufficiently positive potentials only and may suppress the contribution of the lower... 

A detailed insight into the layer composition is obtained with ISS (Fig. 28 a) [69, 70], The excellent depth resolution of the method yields a sharp distribution with a maximum in the centre of the film. Up to 70 at. % Cr(III) are obtained at the maximum for Fel5Cr alloy. A layer of only some few 0.1 nm directly at the surface is still Fe-rich, however, the Fe ions are lost with passivation time [69], There is still ob-... 

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