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  • Organic Chemistry  (2)
  • Polysilanes  (2)
  • Addiction  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Ethynylene-disilanylene copolymers (1991)
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 545-565 
    Details
    ISSN: 1572-8870
    Keywords: Polysilanes ; sigma-pi conjugation ; mesophases ; polymer crystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683516
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  • 2
    Electronic Resource
    Electronic Resource
    Nicotine addiction: a re-analysis of the arguments (1992)
    Springer
    Psychopharmacology 108 (1992), S. 408-410 
    Details
    ISSN: 1432-2072
    Keywords: Smoking ; Nicotine ; Dependence ; Addiction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper evaluates the arguments put forward by Robinson and Pritchard (R&P, this volume) that the conclusions of the US Surgeon General (USDHHS 1988) that nicotine is addictive were ill founded. R&P state that nicotine does not cause intoxication, that many smokers do not exhibit compulsive use, that nicotine is not a euphoriant, that nicotine is a weak reinforcer in other species, that non-pharmacological aspects of smoking are important and that negative affect control accounts for more of the variance in questionnaire measures of smoking motives than does habit. This paper points out that intoxication and a euphoriant effect are not normally considered to be central to dependence potential, that no addictive drug results in compulsive use in all users in all situations, that animals do reliably self-administer nicotine, that evidence concerning the apparent importance of non-pharmacological components of smoking do not diminish the importance of pharmacological aspects and that “variance accounted for” of self-report measures of smoking motivation do not bear on the issue of the importance of those motives. The paper concludes with a summary of the essence of the argument that cigarettes are addictive and that nicotine is the primary focus of that addiction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247413
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Photoinitiation of vinyl polymerization by polysilanes (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 1 (1987), S. 7-14 
    Details
    ISSN: 0268-2605
    Keywords: Polysilanes ; photoinitiation ; polymerisation ; vinyl monomers ; thin films ; photolysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polysilanes were found to photoinitiate the polymerization of a variety of vinyl monomers including methyl methacrylate, styrene, ethyl acrylate and acrylic acid. Polymerization initiated by polysilane photolysis is rather insensitive to oxygen inhibition, which may make it especially suitable for polymerization of thin films. The initiation efficiency of poly(phenylmethylsilylene) in styrene was determined from dilatometry data to be 1 × 10-3. This rather low efficiency is counterbalanced by the very high extinction coefficient of polysilane polymers, ca. 4-8 × 103 per silicon atom. Possible reasons for the low initiation efficiency and reduced oxygen inhibition of polysilane photoinitiators are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590010103
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  • 4
    Electronic Resource
    Electronic Resource
    Organosilicon polymers with alternating σ- and π-conjugated systems (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 423-430 
    Details
    ISSN: 0268-2605
    Keywords: organosilicon ; polymers ; semiconducting ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of organosilicon polymers containing polysilane and diethynylaryl units along the polymer backbone were synthesized and examined with respect to their optical absorptions. The results indicate that delocalization takes place through the σ-π conjugated system. Lengthening of π-conjugation leads to lower excitation energies while nearly identical UV-vis spectra are observed with increased Si-Si chain length. Introducing a thiophene unit into the π-system instead of a benzene unit leads to a bathochromic shift reflecting greater σ-π delocalization. The polymers undergo photodegradation, probably via cleavage of the Si-Si bonds, and thermal crosslinking by reaction at the C≡C triple bonds. When doped with iodine, these polymers become semiconducting with conductivity of the order of 10-4 S cm-1.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590080417
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    Paper (German National Licenses)
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