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  • Chemistry  (4)
  • Wiley-Blackwell  (4)
  • 1980-1984  (4)
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  • Wiley-Blackwell  (4)
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  • 1
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligosarcosines, which contain as azobenzene group at the center of the chain and amino groups at both ends [(Sar)n—Azo—(Sar)n], were prepared with the N-carboxyanhydride method. The oligomers were coupled with an equimolar amount of succinyl chloride in the presence of triethylamine. When the condensation was carried out under photo irradiation, the azobenzene group assumed the cis configuration and the intramolecular reaction (cyclization) was facilitated. Intermolecular polycondensation occurred preferentially in the dark, in which case the azo group was trans. Cyclic oligosarcosine, which contains one azo group, was isolated by gel chromatography, and its thermal cis → trans isomerization was examined in dimethylformamide. The isomerization rate depended strongly on the number of sarcosine units n in the oligomer; for very small rings (n 〈 5), the rate constants were less than those for open-chain analogs; for rings of medium size (n = 5 ∼ 10), they were larger than those for open-chain analogs; and for longer chains, no significant difference was observed. This specific chain-length dependence was explained by the conformational restrictions of the cyclic oligomers. The ring-restricted isomerization was evidenced by an isomerization-induced conformational change observed in 1H-nmr spectroscopy.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 1000-1003 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A mechanistic hypothesis is presented which explains the radiation chemistry of poly(methyl α-haloacrylate)s. In order to test the hypothesis poly(methyl α-trifluoromethylacrylate) PMTFMA was synthesized together with copolymers of methyl methacrylate (MMA), and the α-trifluoromethyl analog. The mechanistic hypothesis predicts that PMTFMA should have a higher G scission than PMMA and that it should have no crosslinking propensity. This prediction was verified by experiment. Imaging of PMTFMA as a positive e-beam resist is also presented. The new material is a more sensitive resist than PMMA.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 1012-1018 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new resist system is described which undergoes spontaneous relief image formation. The resist is formulated from end capped poly(phthaladehyde), PPA, and a cationic photoinitiator such as a diaryliodonium or triarylsulfonium metal halide. The extreme sensitivity of the resist is the result of designing for chemical amplification. The desired amplification results from the fact that photolysis of the sensitizer generates acid which catalyzes main chain cleavage of the polyaldehyde. The uncapped polymer is thermodynamically unstable with respect to reversion to monomer at room temperature so a single acid catalyzed scission results in complete depolymerization to volatile monomer. A single radiochemical event is thereby amplified in the sense that it produces an enormous number of subsequent chemical transformations. PPA/onium salt resist films are so sensitive that exposure to low doses of e-beam, X-ray or ultraviolet radiation results in complete self development without post-exposure processing of any kind. The exposed area simply vaporizes.
    Additional Material: 13 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 19 (1981), S. 43-47 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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