Hydrogen-containing siloxane

Organohydrogensilanes are formed as byproducts in the direct synthesis of dimethyldichlorosilane (see Section 4.2.1) and are important in the manufacture of hydrogen-containing siloxanes and organofunctional silanes (see... 

Special methods of incorporation alkyl peroxide bridging to vinyl containing siloxane polymers used for conductive applications improved curing characteristics decreased by the presence of carbon black crosslinking based on platinum catalyzed polyvinylmethyl siloxane and polymethyl hydrogen siloxane is not inhibited by carbon black in situ silica formation in fonnation of PDMS nanocomposite, montmorillonite was delaminated in polymer prior to crosslinking ... 

Fig. 7.18 Calibration plots for hydrogen peroxide oxidation obtained using Pt coated with a ferrocene-containing siloxane-based copolymer at three different potentials, as indicated in the figure. The surface concentration of the copolymer was 1.7 x 10 molcm . Solution deaerated 0.1 mol dm pH 7 phosphate buffer. (Reproduced from [171 ] with the permission of Elsevier Ltd.)...

Siloxane so- lak- san n [silicon -I- oxygen -i- methane] (1917) (1)A chemical group with the structure shown in which the Rs are usually alkyl and can be alkyl radicals or even just hydrogen. (2) A compound containing siloxane links. A simple representative is hexamethyldi-siloxane, (CH3)3SiOSi(CH3)3. Siloxane links are common in silicone resins. See Silicone. 

Commercially available chlorosilanes can be used normally without further purification. Chlorosilanes stored in a laboratory for a long time may contain siloxanes by hydrolysis. They are purified by distillation before use. Hydrogen chloride contained in chlorosilanes sometimes prohibits reactions. In this case, chlorosilanes are treated with molecular sieves and potassium carbonate. 

Vulcanization. Generally this is carried out by the action of peroxides, which can cross-link the chains by abstracting hydrogen atoms from the methyl groups and allowing the resulting free radicals to couple into a cross-link. Some varieties of polysdoxanes contain some vinylmethyl siloxane units, which permit sulfur vulcanization at the double bonds. Some Hquid (short-chain) siHcones can form networks at room temperature by interaction between thek active end groups. 

An understanding of the surface chemistry of silica is required to interpret its chromatographic properties. The silica surface consists of a network of silanol groups, some of which may. be hydrogen bonded to water, and siloxane groups, as shown in Figure 4.2. A fully hydroxylat silica surface contains about 8... 

Fig. 10.2 (A) Cross-section SEM micrograph of the hybrid membrane containing the receptor 1, (B) membrane transport concentration profiles and (C) molecular recognition principles of acidic I and zwitterionic II L-phenylalanine in the heteropoly-siloxane material membrane (1-hydrogen bonding, 2-charge interaction, 3-Van der Waals forces) [29].

The amount of Pt(0) required by Eq. (6) precipitated from hexane after several days. All the MeCl2SiH was consumed, and products shown in Eq. (6) were the principal ones. Hydrogen chloride was carried from the system with hydrogen, so a complete material balance was not achieved. The siloxanes contained units such as MeHClSiOi/2. However, Eq. (6) approximately described the reduction of chloroplatinic acid by MeCl2SiH. 

Condensation of diethyl difluorosilane with 100% hydrogen peroxide in the presence of ammonia results in the formation of ethoxysilane, whereas an analogous condensation with diethyl dichlorosilane produces polymeric peroxides containing ethoxy and siloxane units. The initially formed straight chain or cyclic peroxides probably rearrange to products 3 or 4 containing alkoxy and siloxane moieties (equation 5) . 

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