Hydrodynamics and conformation of poly(ethylene(tetramethyl)disilene)

Tverdokhlebova, I.I.; Sutkevich, O. I.; Ronova, I. A.; Polyakov, Yu. P.; Gusel'nikov, L.Ye.; Pavlova, S.-S.A.

doi:10.1016/0032-3950(88)90336-x

Cited by 4 publications

(5 citation statements)

References 6 publications

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“…We suggest that the deposit can be formed by a mechanism similar to that assumed for the decomposition of poly(dimethylsi1ane) (reaction steps [11]- [13] in Scheme 4). The w Me2SiMe2SiCH; radical, which can be also formed, can undergo rearrangement into the w M e , S i -CH,-Me2Si * radical, or experience36 cleavage of a methyl group to give +jrMe,Si-MeSi=CH,.…”

Section: Resultsmentioning

confidence: 71%

Laser evaporation of some solid organosilicon polymers

Pola

Vítek

Polyakov

et al. 1991

Applied Organom Chemis

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Continuous wave (cw) C 0 2 laser irradiation of some organosilicon polymers composed of -Me,Si-, -Me2SiMe,SiCH,-, RMeSi-and RMeSiMe,SiCH,CH,-units (where R =methyl, adamantyl, phenyl and hydrogen) leads to the evaporation of the polymer and is dominated by the formation of a solid deposit that has a continuous structure. It is assumed that chemical changes occur prior to the transfer of ejected material to the gas phase and that these consist mainly of the formation of high molecular biradicals or 1,t-disilacyclobutane monomer that both re-polymerize spontaneously upon their deposition onto a nearby cold surface. The mechanism of these specific decompositions of the polymers is assessed on the basis of the IR spectra of the deposits and, for the minor gaseous products, identification by GC MS techniques.

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Section: Resultsmentioning

confidence: 71%

Laser evaporation of some solid organosilicon polymers

Pola

Vítek

Polyakov

et al. 1991

Applied Organom Chemis

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“…In contrast to most of the other silacyclobutanes, which start to polymerize on heating to 210 °C, 1,2-TMDSCB − and its 1,1,2-Me-2-Et analogue ( 5 ) were reported by Gusel’nikov et al to undergo spontaneous exothermal polymerization at room temperature via Si–Si bond cleavage with formation of high-molecular-weight poly(ethylenedisilene). Herein this process was followed by Raman spectroscopy, and the results are presented in Figure .…”

Section: Resultsmentioning

confidence: 97%

“…As a possible mechanism of 1 polymerization, Gusel’nikov et al − , proposed thermal ring opening. However, this mechanism can now be excluded on the following grounds.…”

Section: Resultsmentioning

confidence: 99%

“…The interest in 1 is due not only to its structure (hitherto unknown!) but also to its reported capability for spontaneous polymerization on heating to room temperature with the formation of high-molecular-weight poly(ethylenetetramethyldisilene) ([−CH 2 Me 2 SiSiMe 2 CH 2 −] n ). − Before 1980, only a few differently Si- and C-substituted 1,2-disilacyclobutanes had been described. − …”

Section: Introductionmentioning

confidence: 99%

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Unstable 1,1,2,2-Tetramethyl-1,2-disilacyclobutane and Its Polymerization. Vibrational Spectroscopy and Quantum-Chemistry Study

et al. 2012

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The structure of 1,1,2,2-tetramethyl-1,2-disilacyclobutane (1) has been investigated by experimental means, by Raman and IR spectra, and by quantum-chemical calculations at various levels of theory. All the data obtained show that the four-membered ring of 1 is puckered, the ring puckering mode being 80 cm–1 and the barrier to planarity 1.76 kcal/mol (617 cm–1). Temperature investigations of the Raman spectrum have shown that the liquid 1 solidifies into a plastic mesophase at ∼210 K and crystallizes below ∼110 K. Strain energies (SEs) for 1, the parent molecule 1,2-disilacyclobutane (2), and, for comparison, their 1,3-isomers (3 and 4) were estimated as enthalpies of corresponding homodesmic reactions taken with a reversed sign. These values (in kcal/mol) for 1 (8.6) and 2 (12.4) appeared lower than those for 3 (18.3) and 4 (19.6). To rationalize these results, a QTAIM topological analysis of electron density distribution was carried out for 1–4. Examination of the molecular graphs has demonstrated that the Si–Si bond paths (BPs) in 1 and 2 are significantly bent (“banana” bonds), thus decreasing the SE of these molecules. The corresponding Si–Si BP lengths are increased by Δ ≈ 0.03 Å in comparison to the corresponding endocyclic Si–Si interatomic distances, while the Si–C BPs in all four molecules are nearly straight lines (Δ ≈ 0.002 Å). Monitoring of the process of 1 polymerization on heating to room temperature has revealed that this process is not spontaneous, as was supposed previously, but is initiated by minor radical impurities. Indeed, the value of the ring-opening enthalpy for 1 was calculated as 70 kcal/mol, too high for spontaneous thermal polymerization to occur.

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“…-39.19, -39.48 -41.35, -41.84 -14.38 --3c´-39.36, -39.64 -41.05, -41.44 -13.92 -48.30 -3d´-39.51, -39.62 -41.07, -41.15 -13.61 -44.21 -3e´-39.27, -39.46 -41.38, -41.50 -13.49 -42.70 -40.02 3f´-39.44, -39.53 -41.17, -41.43 -13.14 -41.92 -39.81Δm (wt.TG curves of polycarbosilanes 3a-f (1-6) and 3a´-f(7)(8)(9)(10)(11)(12) in air (a) and in argon (b); Δm -weght of the residue. , in the series of both types of polymers the thermooxidative stability of polycarbosilanes decreases with the increase in the number of SiMe 2 units in the linear fragment.…”

mentioning

confidence: 99%

Synthesis of cyclolinear permethylpolycarbosilanes with oligosilane fragments in the backbone and study of their properties

2009

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Cyclolinear permethylpolycarbosilanes were synthesized for the first time by the reaction of 1,3 and 1,4 dihydrodecamethylcyclohexasilanes H 2 Si 6 Me 10 with α,ω diallylpermethyloligo silanes All(SiMe 2 ) n All (n = 1⎯6) in the presence of Karstedt´s catalyst. The molecular weight characteristics, thermal and thermooxidative stability, and the spectral properties of the syn thesized polymers were studied. The dependence of the yield and the molecular weight of the synthesized polymers on the number of the SiMe 2 units in the linear oligosilane fragment of the main chain was established.

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Hydrodynamics and conformation of poly(ethylene(tetramethyl)disilene)

Cited by 4 publications

References 6 publications

Laser evaporation of some solid organosilicon polymers

Laser evaporation of some solid organosilicon polymers

Unstable 1,1,2,2-Tetramethyl-1,2-disilacyclobutane and Its Polymerization. Vibrational Spectroscopy and Quantum-Chemistry Study

Synthesis of cyclolinear permethylpolycarbosilanes with oligosilane fragments in the backbone and study of their properties

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