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Characterization and Some Insights into the Reaction Chemistry of Polymethylsilsesquioxane or Methyl Silicone Resins. INT J POLYM SCI 2012. [DOI: 10.1155/2012/526795] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Structural characterization of a polymethylsilsesquioxane (PMSQ) and a DT-type methyl silicone resin (MeDT) has been carried out by various instrumental analyses including GPC, NMR, gas chromatography, and gas chromatography-mass spectrometry. Although the PMSQ had aMwaround 5000, the resin contained a significant amount of low molecular weight species consisting of T2[MeSi(OH)O2/2] and T3[MeSiO3/2] units, ranging from to including many isomers. One isomer of was isolated of which structure was determined as a cage structure. The species are supposed to consist mainly of cyclotetra- and cyclopentasiloxanes, but presence of strained rings such as cyclotrisiloxane rings also was suggested. In MeDT, species in which the T2units in the molecules from PMSQ is replaced with D2[Me2SiO2/2] were found, for example, , suggesting that general silicone resins consist of similar structures as silsesquioxanes. The Mark-Houwink exponent for these methyl resins was~0.3, indicating the molecular shape to be compact. Investigation on the formation chemistry of the cubic octamers indicates that siloxane bond rearrangement is an important mechanism in the molecule build-up process.
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Polyhedral Oligomeric Silsesquioxanes with Controlled Structure: Formation and Application in New Si-Based Polymer Systems. ADVANCES IN POLYMER SCIENCE 2010. [DOI: 10.1007/12_2010_55] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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Syntheses, Structures, and Properties of Ladder Oligosilanes. PHOSPHORUS SULFUR 2001. [DOI: 10.1080/10426500108546535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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