Phase Deposition

Liquid-phase deposition (LPD) of Si02 is a relatively new process.  

According to this reaction, Si02 may be formed if the concentration of H2SiFe or water is increased, or the concentration of HF is reduced. Experimentally, three processes have been developed based on the above reaction to form Si02 deposit simply by adding either boric acid (H3BO3) or Al, or water to the solution. The deposition rate, 0.01-0.07 A/s depending on solution composition, is very low relative to that of thermal oxide. 

An alternative to solvent-phase synthesis of CEPs is vapor-phase polymerization (VPP). This route was first used for PAn s in 1998 for the deposition of conducting PAn films on cotton fibers, by impregnating the thread with (NH SjOg oxidant and then exposing the surface to aniline vapor.94 Polyacrylamide films coated with conducting PAn (conductivity ca. 10-5 S cm-1) have been similarly prepared.95 

More recently, using the chiral Fe(III) salt Fe(III)(R)-(+)-camphorsulfonate [Fe(III)(R)-HCSA] as chemical oxidant, the direct vapor-phase deposition of optically active PAn/(+)-HCSA films has been achieved on nonconductive substrates such as glass and polyethylene terephthalate). Postpolymerization cyclic voltam-metric and Raman spectral studies showed that these chiral ES films possessed stable electrochemical activity in acidic environments.96 

Many silane coupling agents can be applied to substrates by volatilization in an enclosed chamber under heat or vacuum. In this approach, the substrate is placed within the chamber in a fashion to allow for vapor phase molecules to access all areas that are to be derivatized. This method is commonly used for silanizing glass slides or substrates that are difficult to suspend in a silane solution. Slides are often placed in racks within the chamber and all surfaces get modified 

In an enclosed chamber made of glass or acrylic, such as a vacuum chamber, place the substrate to be modified in such a manner as to expose the surfaces to the vapor phase. 

React for 4-24 hours within the chamber to result in a uniform coating of the substrate surface with organosilane. Often surfaces are coated overnight to complete the reaction. 

The following sections discuss the organosilane compounds commonly used for conjugation to inorganic surfaces. These reagents and many other silane derivatives are available from a number of commercial sources, which include Dow Corning, Gelest, Aldrich, and others. 

Benters et al. (2002) used two approaches to modify APTS surfaces. In one instance, the amine groups were acylated using glutaric anhydride to create carboxylate functionalities, which were then activated with NHS/DCC to form the NHS ester. This derivative could be 

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Preparation of films for sufficiently volatile molecules can also be perfonned by evaporating tire molecules in vacuum (gas-phase deposition) or by tire use of a desiccator which contains tire substrate and tire dilute solution in a vessel separately and which is evacuated to 0.1 mbar and kept under vacuum for several hours ( 24 h). This also results in a vapour-phase-like deposition of tire molecules onto tire substrates. 

J. B. MacChesney, P. B. O Connor, P. V. DiMarceUo, J. R. Simpson, and P. D. La2ay, "Preparation of Low-Loss Optical Pibers Using Simultaneous Vapor-Phase Deposition and Pusion," in Proceedings of t/je Tent/j Internationa/ Congress on G/ass, Ffoto, Japan, Vol. 6 Ceramics Society, Japan, 1974, pp. 50—54. 

Fig. 21. Schematic illustration of the four primary vapor-phase deposition processes used in optical-fiber fabrication outside vapor deposition (OVD), modified chemical vapor deposition (MCVD), plasma vapor deposition (PVD), and vapor axial deposition (VAD) (115).

Another important function of metallic coatings is to provide wear resistance. Hard chromium, electroless nickel, composites of nickel and diamond, or diffusion or vapor-phase deposits of sUicon carbide [409-21-2], SiC , SiC tungsten carbide [56780-56-4], WC and boron carbide [12069-32-8], B4C, are examples. Chemical resistance at high temperatures is provided by aUoys of aluminum and platinum [7440-06-4] or other precious metals (10—14). 

Fabrication methods that are generaby used to make these junctions are diffusion, ion implantation, chemical vapor deposition (CVD), vacuum deposition, and bquid-phase deposition for homojunctions CVD, vacuum deposition, and bquid-phase deposition for heterojunctions and vacuum deposition for Schottky and MIS junctions. 

Fluoroall l-SubstitutedTitanates. Tetraliexafluoroisopropyl titanate [21416-30-8] can be prepared by the reaction of TiCl and hexafluoroisopropyl alcohol [920-66-17, in a process similar to that used for TYZOR TPT (7). Alternatively, it can be prepared by the reaction of sodium hexafluoroisopropoxide and TiCl ia excess hexafluoroisopropyl alcohol (8). The fluoroalkyl material is much more volatile than its hydrocarbon counterpart, TYZOR TPT, and is used to deposit titanium on surfaces by chemical vapor-phase deposition (CVD). 

Gas-phase deposition In this process, a halide of the solute metal is passed in vapour form over the surface of the metal to be coated, which is heated to a temperature at which diffusion can take place. Temperatures of 500-1 300°C or more can be used, depending on the particular system considered. Generally, filler atmospheres are provided to carry the halide vapour these atmospheres are usually reducing gases such as hydrogen, cracked ammonia, etc. or inert gases (helium, argon). 

In fact, the 4- or 3-aminophthalic anhydride (4-APA and 3-APA) gives only intractable oligomers as pointed out later.154 Interesting are the attempts of vapor-phase deposition of 4-APA, 3-APA, and 4-amino naphtlialic anhydride (4-ANA). The sublimation of 3-APA gives only a low yield of polyimide. With both 4-APA and 4-AN A no sublimation took place and oligomeric products were formed before melting.154... 

Polylactides, 18 Poly lactones, 18, 43 Poly(L-lactic acid) (PLLA), 22, 41, 42 preparation of, 99-100 Polymer age, 1 Polymer architecture, 6-9 Polymer chains, nonmesogenic units in, 52 Polymer Chemistry (Stevens), 5 Polymeric chiral catalysts, 473-474 Polymeric materials, history of, 1-2 Polymeric MDI (PMDI), 201, 210, 238 Polymerizations. See also Copolymerization Depolymerization Polyesterification Polymers Prepolymerization Repolymerization Ring-opening polymerization Solid-state polymerization Solution polymerization Solvent-free polymerization Step-grown polymerization processes Vapor-phase deposition polymerization acid chloride, 155-157 ADMET, 4, 10, 431-461 anionic, 149, 174, 177-178 batch, 167 bulk, 166, 331 chain-growth, 4 continuous, 167, 548 coupling, 467 Friedel-Crafts, 332-334 Hoechst, 548 hydrolytic, 150-153 influence of water content on, 151-152, 154... 

Vapor-phase deposition polymerization polyimide synthesis by, 303 PQ and PPQ synthesis by, 312... 

Deposition of adamantane from petroleum streams is associated with phase transitions resulting from changes in temperature, pressure, and/or composition of reservoir fluid. Generally, these phase transitions result in a solid phase from a gas or a liquid petroleum fluid. Deposition problems are particularly cumbersome when the fluid stream is dry (i.e., low LPG content in the stream). Phase segregation of solids takes place when the fluid is cooled and/or depressurized. In a wet reservoir fluid (i.e., high LPG content in the stream) the diamondoids partition into the LPG-rich phase and the gas phase. Deposition of diamondoids from a wet reservoir fluid is not as problematic as in the case of dry streams [74, 75]. 

Figure 16.3 Vapor phase deposition of molecules and gradients of coverage of molecules formed on a surface.

It is therefore unnecessary to alter the chemical properties of the bulk material, e.g. by using vapor phase deposition of sensitizer and monomer. This can be seen by comparison of ATR-IR and ESCA spectra of grafted PP surfaces (Figure 3). 

Thin Films from Vapor-phase Deposition Techniques 1008... 

Milliron, D. I Raoux, S. Shelby, R. M. Jordan-Sweet, J. 2007. Solution-phase deposition and nanopatterning of GeSbSe phase-change materials. Nature Mater. 6 352-356. 

Successive Ionic Layer Adsorption and Reaction (SILAR) and Related Sequential Solution-Phase Deposition Techniques... 

SILAR AND RELATED SEQUENTIAL SOLUTION-PHASE DEPOSITION TECHNIQUES... 

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