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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of star-shaped polydimethylsiloxanes containing SiO2 core units (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 1973-1983 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Star-shaped polysiloxanes consisting of SiO2 cores and polydimethylsiloxane (PDMS) branches were successfully prepared by three methods using functionalized solvent-soluble silicates as a starting material. The first method involved the lithiation of a Si—OH functional silicate with butyllithium, followed by reaction with hexamethylcyclotrisiloxane (D3) and termination with a chlorosilane to afford a star polymer. In this case, the chain ends were substituted with vinyl or Si—OH functional groups. In the second method, a Si—Cl functional silicate was used as the source of the SiO2 core. A PDMS chain with a lithium silanolate terminal group was reacted with the Si—Cl functional silicate to provide a star polymer. In the third method, a PDMS chain with a diethylamino group at one chain end was reacted with the Si—OH functional silicate to form a star polymer. The Mark-Houwink constant a of the star polymer was 0,74, which is very close to that of a linear PDMS.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950608
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  • 2
    Electronic Resource
    Electronic Resource
    Poly(silmethylene)-based polymer blends. I. In situ polymerization of 1,3-disilacyclobutanes in silicon-based polymers (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 399-405 
    Details
    ISSN: 0887-624X
    Keywords: poly(diphenylsilmethylene) ; in situ polymerization ; polymer blends ; ring-opening polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in situ polymerization of 1,1,3,3-tetraphenyl-1,3-disilacyclobutane with or without a catalyst in flexible organo-silicon polymers was demonstrated to provide poly(silmethylene)-based polymer blends. An alternative route, which implies preparation of blends via synthesis of a flexible polymer in the presence of a rigid polymer, was also promising. The resulting polymer blends were characterized by DSC, dynamic mechanical analysis, and solvent extraction. No chemical interaction is observed between component polymers of blends prepared by the in situ bulk polymerization method while formation of block or graft copolymers comprising poly(diphenylsilmethylene) and flexible polymers is suggested when in situ copper-catalyzed polymerization was employed. A morphological difference between samples synthesized by the different methods was suggested by microscopic observation. © 1997 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Poly(diarylsilmethylene)s, I. Synthesis and characterization (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2821-2831 
    Details
    ISSN: 0887-624X
    Keywords: poly(diarylsilmethylene)s ; ring-opening polymerization ; disilacyclobutanes ; melt viscosity ; crystalline polymer ; DSC ; x-ray diffraction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(diarylsilmethylene)s with phenyl or tolyl substituents on Si atoms were synthesized by ring-opening polymerization of corresponding 1,1,3,3-tetraaryl-1,3-disilacyclobutanes, and were characterized by means of DSC, x-ray diffraction and melt viscosity measurements. Three preparative routes including catalytic and noncatalytic polymerization methods were examined to see differences in properties of the resulting polymers. The polymers thus obtained were crystalline and soluble in limited solvents such as diphenyl sulfone at tem-peratures above 250°C. Poly(diphenylsilmethylene) exhibited a melting temperature of about 350°C, whereas those of polymers with tolyl groups were observed in a temperature range between 310 and 330°C. The melt viscosity of the poly(diarylsilmethylene)s was measured to obtain insight into the molecular weights of the polymers, and the results indicated that the molecular weights are modifiable by varying the monomer-to-catalyst ratio when solution polymerization is employed. The DSC and x-ray studies were also carried out with focusing on the melting and crystallization behavior of these polymers. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331616
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  • 4
    Electronic Resource
    Electronic Resource
    Poly(silmethylene)-based polymer blends. II. Synthesis and characterization of poly(diphenylsilmethylene)/poly(methylphenylsilmethylene) blends1 (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1431-1442 
    Details
    ISSN: 0887-624X
    Keywords: poly(silmethylene) ; in situ polymerization ; polymer blend ; thermal stability ; dynamic mechanical properties ; graft copolymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(diphenylsilmethylene) (PDPSM)/poly(methylphenylsilmethylene) (PMPSM) binary polymer blends were synthesized by in situ ring-opening polymerization of 1,1,3,3-tetraphenyl-1,3-disilacyclobutane in PMPSM. Three catalytic methods as well as a noncatalytic method were employed. Radical initiators such as an organic peroxide or azo-compound proved to be the effective catalysts in addition to copper compounds. Blend samples were characterized in detail by DSC, dynamic mechanical analysis, solvent extraction, and microscopic observation to clarify the relationship between the preparative method and the properties of these polymer blends. It is strongly suggested that a part of PMPSM is converted into an insoluble form via formation of PDPSM-PMPSM block or graft copolymers in the case of the in situ copper-catalyzed polymerization in xylene. The formation of block or graft copolymers is also suggested for samples prepared by the in situ bulk polymerization in the presence of a radical initiator. However, PMPSMs simultaneously underwent molecular weight decrease and insolubilization probably due to polymer chain scission and crosslinking, respectively, when the latter method was employed using PMPSM with very high molecular weight. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1431-1442, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Poly(diarylsilmethylene)s, II. Thermal and mechanical properties1 (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1317-1326 
    Details
    ISSN: 0887-6266
    Keywords: ply(diarylsilmethylene)s ; pyrolysis ; TG-DTA ; tolyl substituents ; thermostability ; mechanical properties ; Si-C ceramics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal and mechanical properties of poly(diarylsilmethylene)s (PDArSMs) with phenyl, m-tolyl or p-tolyl substituents on Si atoms were investigated. According to the TG-DTA, poly(diphenylsilmethylene) (PDPSM) remained almost unchanged in weight up to about 400°C, and showed two-step weight loss in the temperature range between ca. 400 and 700°C in an air atmosphere. The first decomposition step seems assignable to elimination of aryl groups while the second one is presumably due to oxidative decomposition which is evident from a large exothermic peak in the DTA trace. Thermostability of PDArSMs with tolyl groups were comparable to that of PDPSM when the measurement was conducted under nitrogen, whereas the polymers having tolyl substituents were highly thermally unstable in air compared with PDPSM. These polymers exhibited a gain in weight accompanied with a violent exothermic reaction in the early stage of thermal decomposition in air. This thermal instability of the tolyl-substituted polymers can be explained by high sensitivity of the tolyl groups toward oxidative decomposition. Analysis of pyrolyzed products of PDArSMs suggested that these polymers underwent radical cleavage of Si-aryl bonds to provide network materials which can be precursors for Si-containing ceramics. Mechanical properties of PDPSM are also discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of poly(silylenemethylene)s by positron annihilation lifetime spectroscopy. I. (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 755-761 
    Details
    ISSN: 0887-6266
    Keywords: positron annihilation lifetime spectroscopy ; free volume ; transition temperatures ; poly(silylenemethylene)s ; dynamic mechanical analysis ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Amorphous and crystalline poly(silylenemethylene)s with the repeating PhRSiCH2 (R : Me or Ph) units were characterized by positron annihilation lifetime spectroscopy (PALS) to gain insights into the molecular motions of these polymers. The temperature dependence of the ortho-positronium lifetime (τ3) and intensity (I3) was examined from 50 to 470 K for each sample. The glass transition temperature of each polymer was easily distinguished by a change in the slope of τ3 spectrum. Both polymers exhibited a steep drop of I3 at 130-140 K being probably assignable to the transition arising from the motions of phenyl groups, which was almost undetectable by means of differential scanning calorimetry or dynamic mechanical analysis. Several other transitions of these polymers detected by PALS are also discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 755-761, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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