18191-59-8Relevant articles and documents
Ohno et al.
, p. 2870,2873, 2875 (1977)
Alkenylsilane structure effects on mononuclear and binuclear organotitanium-mediated ethylene polymerization: Scope and mechanism of simultaneous polyolefin branch and functional group introduction
Amin, Smruti B.,Marks, Tobin J.
, p. 2938 - 2953 (2007/10/03)
Alkenylsilanes of varying chain lengths are investigated as simultaneous chain-transfer agents and comonomers in organotitanium-mediated olefin polymerization processes. Ethylene polymerizations were carried out with activated CGCTiMe2 and EBICGCTi2Me4 (CGC = Me2Si(Me4C5)(NtBu); EBICGC = (μ-CH2CH2-3,3′){(η5-indenyl)[1- Me2Si(tBuN)]}2) precatalysts in the presence of allylsilane, 3-butenylsilane, 5-hexenylsilane, and 7-octenylsilane. In the presence of these alkenylsilanes, high polymerization activities (up to 10 7 g of polymer/(mol of Ti-atm ethylene·h)), narrow product copolymer polydispersities, and substantial amounts of long-chain branching are observed. Regardless of Ti nuclearity, alkenylsilane incorporation levels follow the trend C8H15SiH3 6H 11SiH3 ≈ C4H7SiH3 3H5SiH3. Alkenylsilane comonomer incorporation levels are consistently higher for CGCTiMe2-mediated copolymerizations (up to 54%) in comparison with EBICGCTi2Me 4-mediated copolymerizations (up to 32%). The long-chain branching levels as compared to the total branch content follow the trend C 3H5SiH3 4H7SiH 3 ≈ C6H11SiH3 ≈ C 8H15SiH3, with gel permeation chromatography-multi-angle laser light scattering-derived branching ratios (gM) approaching 1.0 for C8H15SiH3. Time-dependent experiments indicate a linear increase of copolymer Mw with increasing polymerization reaction time. This process for producing long-chain branched polyolefins by coupling of an α-olefin with a chain-transfer agent in one comonomer is unprecedented. Under the conditions investigated, alkenylsilanes ranging from C3 to C8 are all efficient chain-transfer agents. Ti nuclearity significantly influences silanolytic chain-transfer processes, with the binuclear system exhibiting a sublinear relationship between Mn and [alkenylsilane]-1 for allylsilane and 3-butenylsilane, and a superlinear relationship between Mn and [alkenylsilane]-1 for 5-hexenylsilane and 7-octenylsilane. For the mononuclear Ti system, alkenylsilanes up to C 6 exhibit a linear relationship between Mn and [alkenylsilane]-1, consistent with a simple silanolytic chain termination mechanism.
Reaction of Hydrogen Peroxide with Organosilanes under Chemical Vapour Deposition Conditions
Moore, Darren L.,Taylor, Mark P.,Timms, Peter L.
, p. 2673 - 2678 (2007/10/03)
When a stream of vapour at low pressure which contained a mixture of H2O2 with an organosilane, RSiH3 (R = alkyl or alkenyl), impinged on a silicon wafer, deposition of oxide films of nominal composition RxSiO(2-0.5x), where x 3 or higher alkenyl groups. or higher alkenylgroups. Possible mechanism for the Si-C bond cleavage reaction are discussed, with energetic rearrangement of radical intermediates of type Si(H)(R)(OOH)' being favoured.
