Silicones moisture-cured

Moisture-Curing Silicones. The formulation of moisture-curing sHicones includes a sHicone polymer, filler, a moisture-reactive cross-linker, and sometimes a catalyst. The most common sHicone polymer used in sealant formulations is an alternating sHicon—oxygen backbone with methyl groups attached to the sHicon such as the sHicone polymer (1). 

Scheme 9. Crosslinking reaction of a two-part moisture cure silicone adhesive system.

Silicon oxychloride, in fiber optic fabrication, 11 138 Silicon-oxygen (Si-O) backbone, in moisture-curing silicones, 22 32... 

Silicones. Commercially available silicone sealants are typically one of three curing types moisture-reactive (curing) sealants, moisture-releasing (latex) sealants, and addition-curing sealants. Of these three types, moisture-curing silicones make up the vast majority of silicone sealants sold. 

Most moisture-curing silicones have good general adhesion to a variety of substrates. However, adhesion can be markedly improved with different combinations of silanes. The more common silane adhesion promoters are categorized as amine functional, eg, 3-aminopropyltrimethoxysilane [13822-56-5]y 3-aminopropyltriethoxysilane [919-30-2] y or IV-(2-aminoethyl)-3-aminopropyltrimethoxysilane [1760-24-3] as epoxy functional, eg, 3-glycidoxypropyltrimethoxysilane [2530-83-8] (2) and 2-3(3,4-epoxycyclohexyl)ethyltrimethoxysilane [3388-04-3] (3) as mercapto functional, eg, 3-mercaptopropyltrimethoxysilane [4420-74-0] or as methacrylate functional, eg, 3-methacryloxypropyltrimethoxysilane [2530-85-0] (4). 

Moisture-curing silicones contain polydimethylsiloxane (PDMS) with water-reactive end groups. The hydrolysis reactions with acetate, ethyl ether and butanone ketoxime end groups are as shown below. 

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