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Divinyltetramethyldisiloxane, commercially designated as IOTA 1002, is a vital organosilicon compound with the systematic name 1,3-Diethenyl-1,1,3,3-tetramethyldisiloxane. Its well-defined structure features a central disiloxane backbone (Si-O-Si) flanked by two methyl groups and terminated by highly reactive vinyl (ethenyl, -CH=CH₂) groups on each silicon atom. This symmetrical molecule is characterized by its CAS No. 2627-95-4 and EINECS 220-099-6, with a molecular formula of C₈H₁₈OSi₂ and a molecular weight of 186.40 g/mol.
Key Physical Properties:
IOTA 1002 presents as a colorless transparent liquid under standard conditions. It boasts a boiling point range of 133-139°C and a relatively low density of 0.818 g/cm³. Its refractive index falls between 1.4118 and 1.4123. A hallmark of IOTA 1002 is its high purity, typically guaranteed at ≥99.5%, ensuring consistent performance. This high purity corresponds to a vinyl group content of approximately 29.0% by weight, a critical metric for its reactivity. The compound is insoluble in water.
Primary Function: Vinyl Dual-End Additive/Intermediate
The defining feature of IOTA 1002 is the presence of reactive vinyl groups at both ends of its molecule. This bifunctionality makes it an exceptionally versatile building block and additive within silicone chemistry:
Silicone Polymer Modification & Synthesis: It serves as a fundamental chain extender and crosslinker in various silicone systems:
Silicone Rubber & Gel: Incorporated into high-consistency rubber (HCR), liquid silicone rubber (LSR), and silicone gels to introduce vinyl sites for platinum-catalyzed addition curing (hydrosilylation). This enhances crosslink density, modulus, and tear strength.
Vinyl Silicone Resins: Acts as a key monomer or co-monomer in synthesizing resins where pendant or terminal vinyl groups are required for subsequent curing or functionalization.
Vinyl Silicone Oils: Used as a starting material or endblocker to produce linear or branched vinyl-functional polydimethylsiloxane (PDMS) oils. These oils are crucial intermediates for making surfactants, modifiers, or crosslinkable fluids.
Platinum Complex Production: IOTA 1002 is a critical intermediate in synthesizing certain platinum-based catalysts (platinum complexes) used extensively in hydrosilylation cure systems. Its vinyl groups coordinate with platinum during complex formation.
Significance in Silicone Technology:
The symmetrical structure and high purity of IOTA 1002 ensure predictable reactivity and minimal side reactions. Its dual terminal vinyl functionality allows it to act as a molecular bridge, efficiently incorporating into polymer chains or creating crosslinks between hydride-functional (Si-H) species during curing. This controllably modifies the mechanical properties (elasticity, strength, hardness) and processing characteristics of the final silicone product. Its role in platinum catalyst synthesis further underpins the efficiency of the ubiquitous addition cure process.
In essence, Divinyltetramethyldisiloxane (IOTA 1002) is an indispensable, high-purity workhorse chemical. Its unique structure enables the tailored design and production of a vast array of high-performance silicone materials, from flexible rubbers and gels to specialized resins, oils, and the catalysts that cure them.