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  • Polymer and Materials Science  (8)
  • mesophases  (2)
  • Bissilylamines  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Some recent developments in polysilane chemistry (1992)
    Springer
    Journal of inorganic and organometallic polymers and materials 2 (1992), S. 29-45 
    Details
    ISSN: 1572-8870
    Schlagwort(e): Polysilenes ; polysilanes ; liquid crystals ; mesophases ; birefringence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract (I) Ordered and disordered polysilane copolymers: Condensation of ClSiMe2Si(n-Hex)2SiMe2Cl with Na/K in toluene at 90°C produced a polymer with a strongly bimodal molecular weight distribution. The high-M w and low-M w portions were separated by fractional precipitation with 2-propanol, and the properties of the two fractions were investigated.29Si-NMR spectra show that the low-M w fraction is fully ordered but the high-M w fraction is randomized. (II) Liquid crystalline polysilanes: Condensation ofn-Bu(n-Hex)SiCl2 with Na in toluene led to a homopolymer which is a rubbery solid at 25°C. The polymer undergoes a second-order transition at −45°C and a first-order (melt) transition at −20°C. X-ray diffraction shows that the polymer has the same structure, a columnar hexagonal lattice, in all three phases; from −20 to 〉200°C, it exists in a columnar liquid crystalline mesophase. Similar hexagonal mesophases were observed at 25°C for the family of copolymers, (n-Hex2Si) n (Alk2Si) m , Alk =n-Pentyl,n-Bu,n-Pr, Et, Me.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00696534
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  • 2
    Digitale Medien
    Digitale Medien
    Ethynylene-disilanylene copolymers (1991)
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 545-565 
    Details
    ISSN: 1572-8870
    Schlagwort(e): Polysilanes ; sigma-pi conjugation ; mesophases ; polymer crystals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Polymers of structure (SiR2SiR2-C ≡ C-SiR2′SiR2′-C ≡ C) n , in which ethynylene units alternate with disilylene units, have been prepared by two routes: (a) condensation of dichlorodisilanes with dilithium derivatives of 1,2-diethynyldisilanes and (b) ring-opening polymerization of strained cyclic disilanylene-acetylnes, (SiR2SiR2C ≡ C)2. The polymers display UV absorption near 240 nm indicative of σ − π conjugation between the Si2 and the C ≡ C moieties. Polymers with R=R′=n-Bu or R=n-Bu, R′=Ph, undergo solid-state transitions to form liquid crystalline mesophases resembling those observed for many poly(silylenes). Single crystals were obtained for the polymer with R=R′=CH3, by precipitation from dilute cyclohexane solution. The solid-state properties and structures of this family of polymers are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00683516
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  • 3
    Digitale Medien
    Digitale Medien
    Synthetic and Structural Studies of 1-Sila-2,5-diaryltetrazenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1579-1583 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Silatetrazenes ; Nitrogen-silicon ring systems ; Bissilylamines ; Silicon-29 solid state NMR ; Aryl azides ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction between aryl azides and lithiated aryl amines leads to tetrazenes 3 and 9 which contain a chain of four nitrogen atoms. Reaction with different halosilanes gives the cyclic silatetrazenes 10, 12, and 15 where substitutents on the silicon vary form alkyl to hydrogen and chlorine atoms. The structures of 10, 12, and 15 in the solid state are reported. Variation of the solvent and the Lewis acidity of the halosilane influence the ratio of silatetrazene to side products, bissilyated amines. These effects are studied for different halosilanes.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19971301105
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  • 4
    Digitale Medien
    Digitale Medien
    29Si nuclear magnetic resonance of dimethyl and phenylmethyl containing polysilanes (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 701-712 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 29Si-NMR spectra are reported for poly(methylphenylsilylene), 1, poly(1,1,2-trimethyl-2-phenyldisilene) 2, two samples of poly(dimethylsilylene-co-phenylmethylsilylene), 3a and 3b, and poly(phenylmethylsilylene-co-n-hexylmethylsilylene), 4. The spectra of 3a, 3b, and 4 indicate that these polymers contain blocklike regions with considerable segregation of RMeSi and PhMeSi groups. The spectrum of 2 shows no evidence for stereospecific polymerization. The preparation of 2 from 1,1,2-trimethyl-2-phenyldichlorosilane is also described.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1988.080260303
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  • 5
    Digitale Medien
    Digitale Medien
    29Si nuclear magnetic resonance of dialkylpolysilanes (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 713-720 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The silicon-29 nuclear magnetic resonance spectra of a number of dialky- and alkylmethylpoly-silanes are reported. Polysilanes composed of asymmetrically substituted silylenes (i.e., alkylmethylsilylenes) exhibited very broad resonance lines attributed to diastereomeric chemical shifts of stereogenic silylenes alpha and beta to the observed nucles Symmetrically substituted polysilanes showed a single narrow peak. The 29Si chemical shifts for these polysilanes decrease with increasing steric bulk of the substituents, varying inversely with the electronic excitation energy.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1988.080260304
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  • 6
    Digitale Medien
    Digitale Medien
    Organosilane polymers: Formable copolymers that contain methyl(β-phenethyl)silylene or cyclohexyl(methyl)silylene units (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 225-238 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: High molecular weight polysilane copolymers which contain the units in the title were prepared in high yield by sodium coupling the corresponding organodichlorosilanes in toluene. These copolymers are highly soluble in common solvents and can be drawn into fibers or formed into films by molding or casting. They are also photoactive.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1984.170220121
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  • 7
    Digitale Medien
    Digitale Medien
    Organosilane polymers: Formable copolymers containing dimethylsilylene units (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 159-170 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Formable silane copolymers that contain dimethylsilylene units were synthesized and characterized. These polymers have high molecular weights and appreciable solubility in common solvents, can be molded or cast into films or drawn into fibers, and are photoactive.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1984.170220116
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  • 8
    Digitale Medien
    Digitale Medien
    Organosilane high polymers: Oxidation of polycyclohexylmethylsilylene (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 23 (1985), S. 469-473 
    Details
    ISSN: 0360-6384
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1985.130230904
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  • 9
    Digitale Medien
    Digitale Medien
    Organosilane high polymers: Synthesis of formable homopolymers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 21 (1983), S. 819-822 
    Details
    ISSN: 0360-6384
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1983.130211007
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  • 10
    Digitale Medien
    Digitale Medien
    Organosilane high polymers: Electronic spectra and photodegradation (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 21 (1983), S. 823-829 
    Details
    ISSN: 0360-6384
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1983.130211008
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