Silicone sol-gel film

Figure 9.4 DTA plots of silicone sol-gel films with or without incorporated microcapsules [1 ]. Curve 1 traditional silicone sol-gel coating. Curve 2 silicone sol-gel composite coating containing organosilicone and ZrOj...

The most common sol—gel system that has been electrochemically deposited is based on silane, although electrochemical deposition of non-silicon sol-gel films from metal alkoxides has also been reported [3-6]. Early studies mainly dealt with the electrochemical deposition behavior of different silanes and their mixtures. The silanes include tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), and organofunctional silanes such as 3-aminopropyltriethoxysilane (APTES) and 3-mercaptopropyltrimethoxysilane (MPTMS). The electrochemically deposited silane films find applications in electroanalysis, corrosion... 

The electrochemical deposition approach is versatile and applicable to various sol-gel systems, including silanes and metal alkoxides. Most of the research has focused on the electrodeposition of silane-based sol-gel films. The latter are typically electrodeposited from aqueous solutions of the monomers in the presence of ethanol or methanol as a cosolvent The deposition is usually carried out at cathodic potentials, although a few groups [11,14,15] also reported the anodic electrodeposition process. Electrodeposition of non-silicon sol-gel films from... 

The mechanism described above is generally accepted, and it is also applicable for the cathodic electrodeposition of non-silicon sol-gel films from their alkox-ide precursors. Mandler and coworkers [2] added phenolphthalein into the silane solution and observed purple color upon applying -1.3V versus Ag/AgCl on the cathode surface. This indicated that the surface pH exceeded 8.2, which could... 

Even cationic species such as the (hydrated) hydrogen ion (H ) can be lured into the hydrophobic silicone films from water medium as long as they contain appropriate additives to allow penetration of the analyte. For instance, Nivens et al. [140,141] have reported fabrication of silicone/ sol-gel films using a hydroxy-terminated poly(dimethyl siloxane (PDMS-OH), tetraethoxysilane (TEOS) and 3-ami-nopropyltriethoxysilane (APTES) mixture in ethanol-water. Tetramethylammonium hydroxide (TMAOH) is added to the mixture to entrap the fluorescent pH indicator dye 8-hydroxypyrene-l,3,6-trisulfonic acid trisodium salt (HPTS) [102], after base-catalyzed polycondensation of the silanes and the PDMS-OH. Silica optical fibers are stripped from their jacket at the distal end and dip-coated with the indicator gel before the end of gelation (24 h). The optical fluorosensor is able to measure between pH 6.0 and 8.5 for 6 months if stored in buffer medium. 

Figure 11-3. AFM image of a GeSx sol-gel film on a silicon wafer, prepared via route D.

Figure 11-4. X-ray diffraction patterns of GeS sol-gel films on silicon wafers.

Almeida R.M. Sol-gel silica films on silicon substrates. Int. J. Optoelectron. 1994 9 135-142 Almeida R.M., Vasconcelos H.C., Ilharco L.M. Relationship between infrared absorption and porosity in silica-based sol-gel films. SPIE Sol-Gel Opt. HI 1994 2288 678-687 Almeida R.M. Spectroscopy and structure of sol-gel systems. J. Sol-Gel Sci. Technol. 1998 13 51-59... 

The infrared (IR) spectrum reveals vibrations of atoms, ions, and molecular groups. The beauty of the spectrum is the close and accessible relationship between the IR bands and the molecular structure. Certain groups of atoms have characteristic vibrational frequencies that persist in different materials. Therefore, IR spectroscopy is an indispensable tool, widely employed to study sol-gel inorganic and organosilicon materials. FTIR spectroscopy is a common, sensitive, and nondestructive tool to record the IR absorption spectra of sol-gel films on transparent substrates such as silicon wafers, normally in the mid-IR range of 4000-400 cm , with a typical resolution of 4cm . Normal incidence IR absorption spectroscopy is often employed for the characterization of sol-gel materials. Gallardo et al. [18], however, used oblique incidence IR absorption for sol-gel films, which revealed some new structural features. 

A recent competitor to CVD in the planarization of silicon dioxide is the sol-gel process, where tetraethylorthosilicate is used to form spin-on-glass (SOG) films (see Appendix). This technique produces films with good dielectric properties and resistance to cracking. Gas-phase precipitation, which sometimes is a problem with CVD, is eliminated. 

Polycondensation, 10 189-190, 191 as an aging mechanism, 23 64 of polyamide plastics, 19 781-782 polyester formation by, 20 390-391 silicone polymerization via, 22 556-558 in the sol-gel process, 23 61-62 Polycrystalline alloys, 13 523 Polycrystalline diamond films, deposition of, 24 744-745... 

In the sol-gel process, ceramic polymer precursors are formed in solution at ambient temperature shaped by casting, film formation, or fiber drawing and then consolidated to furnish dense glasses or polycrystalline ceramics. The most common sol-gel procedures involve alkoxides of silicon, boron, titanium, and aluminum. In alcohol water solution, the alkoxide groups are removed stepwise by hydrolysis under acidic or basic catalysis and... 

Sol-gel technology - [ALUMINUMCOMPOUNDS - ALUMINIUMOXIDE(ALUMINA) - ACTIVATED] (Vol 2) - [SOL-GEL TECHNOLOGY] (Vol 22) -hydrolysis of tetraalkoxysilanes [SILICON COMPOUNDS - SILICONESTERS] (Vol 22) -for thin films [IHIN FILMS - FILM FORMATION TECHNIQUES] (Vol 23) -htanates for [TITANIUM COMPOUNDS - ORGANIC] (Vol 24) -for vitreous silica [SILICA - VITREOUS SILICA] (Vol 21)... 

Coated abrasives consist of a flexible backing on which films of adhesive hold a coating of abrasive grains. The backing may be paper, cloth, open-mesh cloth, vulcanized fiber (a specially treated cotton rag base paper), or any combination of these materials. The abrasives most generally used are fused aluminum oxide, sol-gel alumina, alnmina-zirconia. silicon carbide, garnet, emeiy, and flint. 

To reduce expense, efforts are made to exploit integrated thin film technologies. For example, arrays have been produced via thin film deposition of the pyroelectric onto a sacrificial layer, e.g. a suitable metal or polysilicon, which is then selectively etched away. Thermal isolation of the pyroelectric element is achieved through engineering a gap between it and the ROIC silicon wafer. Yias in the supporting layer permit electrical connections to be made between the detector and the wafer via solder bonds. Imaging arrays have been produced in this way incorporating sputtered PST and sol-gel formed PZT films. 

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