+) Silane, also called Silicon Hydride, any of a series of covalently bonded compounds containing only the elements silicon and hydrogen, having the general formula SinH2n + 2, in which n equals 1, 2, 3, and so on. The silanes are structural analogues of the saturated hydrocarbons (alkanes) but are much less stable. The term silane is extended to include compounds in which any or all of the hydrogen atoms have been replaced by other atoms or groups of atoms, as in tetrachlorosilane, SiCl4.
- Silanes have been prepared by the reaction of magnesium silicide (Mg2Si) with acids or by the reduction of silicon chlorides with lithium aluminum hydride. All the silanes burn or explode upon contact with air, and they are decomposed by alkaline solutions with formation of hydrogen and hydrous silica. Upon heating, the silanes decompose into hydrogen and silicon; they react with the halogens or hydrogen halides to form halogenated silanes, and with olefins to form alkylsilanes.
- The simplest silane, monosilane (SiH4), is also the stablest; it is a colourless gas that liquefies at -112°C (-170°F) and freezes at -185° C (-301°F). It decomposes slowly at 250°C (482°F), rapidly at 500°C (932°F).
- The instability of the silanes results from the reactivity of the silicon-hydrogen bond; derivatives in which all the hydrogen atoms have been replaced by organic groups, such as tetramethylsilane, Si(CH3)4, resemble the saturated hydrocarbons. The compound dimethyldichlorosilane, (CH3)2SiCl2, is important as the starting material for the dimethylpolysiloxanes, members of the silicone family of polymers. Chlorotrimethylsilane and vinyltrichlorosilane are used to impart water repellency to numerous materials such as cloth, paper, and glass.
+) Các loại Silane chủ yếu hiện nay như sau:
- Silanes are a group of silicon compounds consisting of chlorosilane, alkoxysilane, and silazane. Silanes are used in a wide variety of fields, making use of the unique properties of silicon compounds.
Protection of the functional groups: Protection of the functional groups during synthesis of pharmaceuticals and agricultural chemicals.
Resin modification: Used in resin modification and paint modification, and in surface modification of inorganic materials.
2. Silane coupling agents:
- Silane coupling agents contain at least two different reactive groups within their molecules. One of these functional groups forms chemical bonds with inorganic materials, and the other forms chemical bonds with organic materials. This property enables silane coupling agents to function as intermediaries in bonding organic materials to inorganic materials, which normally tend not to bond with each other.
Higher-quality composite materials: Silane coupling agents improve dispersion during mixing of resins and fillers, and improve the mechanical strength, water and heat resistance, transparency, adhesion and other properties of the composite materials. Silane coupling agents are also highly effective in improving the chemical bonding of heat-cure resins and their compatibility with polymers.
Resin modification/Surface treatment: Reacting a resin with a silane coupling agent can improve its anchorage to inorganic materials, its room-temperature humidity curing properties, and improve its weatherability and resistance to heat, acids and solvents. Silane coupling agents can also be used to treat the surface of inorganic materials to improve the materials' surface characteristics.
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