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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 16 (1983), S. 839-843 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A series of polyamic acids were prepared in N,N-dimethylactamide (DMAc) containing large amount of water, some of which contain the amount of water up to 25%. Their inherent viscosities decreased with the increase of water in DMAc, depending on the electronic properties of dianhydride and reaction condition. The molecular weights and mechanical properties of the polyimides thermally imidized from the polyamic acids were almost independent on the water content in solvent. The decomposition-resynthesis of polyamic acids during the curing was also investigated.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 26 (1991), S. 557-563 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Three pairs of polyimide/polyimide blends (50/50 wt%) with different molecular structures were prepared by two ways, i.e. mixing of the polyamic acid precursors with subsequent imidization, and direct solution mixing of the polyimides. The blends were studied with DMA technique. The results obtained show that all the blends prepared with these two different ways are miscible, as there existed only one glass transition temperature (Tg) for all the blends. It is suggested that the miscibility of these polyimide/polyimide blends is a result of the strong inter-molecular charge-transfer interaction between the chains of their components.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3287-3297 
    ISSN: 0887-624X
    Keywords: optical activity ; dianhydride ; polyimide ; 1,1′-bi-2-naphthol ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new optically active aromatic polyimides containing axially dissymmetric 1,1′-binaphthalene-2,2-diyl units were prepared from optically pure (R)-(+)- or(S)-(-)-2,2′-bis(3,4-dicarboxyphenoxy)-1,1′-binaphthalene dianhydrides and various aromatic diamines via a conventional two-step procedure that included ring-opening polycondensation and chemical cyclodehydration. The optically pure isomer of dianhydride was prepared by a nucleophilic substitution of optically pure (R)-(+)- or(S)-(-)-1,1′-bi-2-naphthol with 4-nitrophthalonitrile in aprotic polar solvent and subsequent hydrolysis of the resultant tetranitrile derivatives, followed by the dehydration of the corresponding tetracarboxylic acids to obtain the dianhydrides. These polymers were readily soluble in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol, etc., and have glass transition temperatures of 251-296°C, and 5% weight loss occurs not lower than 480°C. The specific rotations of the optically active polyimides ranged from +196° to +263°, and the optical stability and chiroptical properties of them were also studied. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3287-3297, 1997
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2681-2685 
    ISSN: 0887-624X
    Keywords: poly(diphenyl-o-tolylmethyl methacrylate) ; one-handed helical conformation ; propeller-propeller transition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diphenyl-o-tolymethyl methacrylate (DPTMA) was synthesized and polymerized using initiators of organolithium complexes with (+)-(2S,3S)-dimethoxy-1,4-bis(dimethylamino) butane (DDB) and (-)-sparteine (Sp) as the chiral ligands. DDB was suitable for its complex effective to prepare optically active poly(diphenyl-o-tolylmethyl methacrylate) (PDPTMA) with one-handed helical conformation, whereas only low-molecular weight polymer was formed when Sp was used as ligand due to the repulsive hindrance between the triarylmethyl group and the ligand. A new mutarotation propeller-propeller transition, was observed for PDPTMA from the optical rotation curves and CD spectra in THF solution. The equivalent period of PDPTMA was estimated to be 14 Å based on the x-ray diffraction. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 143-151 
    ISSN: 0887-624X
    Keywords: polyimide ; poly(amic ester) ; imidazation ; thermogravimetric analysis ; dynamic mechanic analysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of a series of poly(amic methyl ester)s from five aromatic dianhydrides and a diamine, 4,4′-oxydianiline (ODA), are described. These poly(amic ester)s are obtained by the low-temperature polycondensation from dianhydrides derived diesterdiacyl chlorides and ODA in DMAc solution with the inherent viscosities in the 0.5-0.9 dL/g range. These precursors are readily soluble in aprotic solvents. A detailed thermal study of the imidization process is presented, based on dynamic and isothermal TGA measurements, FTIR spectroscopy, and dynamic mechanical analysis. © 1997 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1925-1931 
    ISSN: 0887-624X
    Keywords: helix-selective polymerization ; one-handed screw sense ; optically active polymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mixture of triphenylmethyl methacrylate (TrMA) and methyl methacrylate (MMA) was polymerized with chiral anionic initiator, such as fluorenyl lithium(-)-sparteine [FlLi-(-)-Sp] and fluorenyl lithium-(+)-2S,3S-dimethoxy-1,4-bis(dimethylamino)butane [FlLi-(+)-DDB] in toluene at -78°C. The results show that after the stable helix formed, when FlLi-(+)-DDB was used as the initiator, TrMA and MMA could be copolymerized, whereas when FlLi-(-)-Sp was used, the two monomers tended to be selectively polymerized into two polymers. This phenomenon has been explained by the existence of helix-selective polymerization. © John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1925-1931, 1997
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 27 (1989), S. 475-479 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 40 (1996), S. 57-62 
    ISSN: 0959-8103
    Keywords: polyetherimide ; membrane ; permeability ; permselectivity ; gas separation ; Chemistry ; Polymer and Materials Science
    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: Gas permeability coefficients of a series of aromatic polyetherimides, which were prepared from 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA) and various aromatic diamines, to H2, CO2, O2, N2 and CH4 have been measured under 7 atm pressure and over the temperature range 30-150°C. A significant change in permeability and permselectivity, which resulted from a systematic variation in chemical structure of the polyetherimides, was found. Generally, increases in permeability of the polyetherimides are accompanied by decreases in permselectivity. The order of decrease of the permeability coefficients is as follows: HQDPA-IPDA 〉 HQDPA-DDS 〉 HQDPA-MDA 〉 HQDPA-ODA 〉 HQDPA-DABP 〉 HQDPA-BZD. However, HQDPA-DMoBZD and HQDPA-DMoMDA, with bulky methoxy side-groups on the aromatic rings of the diamine residue, display both high permeability coefficients and high permselectivity. The favourable gas separation property, excellent thermal and chemical stability, and high mechanical strength make HQDPA-DMoBZD and HQDPA-DMoMDA promising candidates for membrane-based gas separation applications.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 485-489 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Photosensitive polyimide BTDA-3MPDA was modified by UV irradiation. The structure of UV-irradiated polyimides was investigated by FTIR and gel fraction measurements. The results showed that longer UV exposure time resulted in a higher extent of crosslinking. The gas permeabilities of hydrogen, oxygen and nitrogen through UV-irradiated polyimides were characterized in a temperature range from 30°C to 90°C. Photocrosslinking resulted in a sharp decline in gas permeability for hydrogen, oxygen, and nitrogen through polyimide in the initial stage of photocrosslinking. Then, as the crosslinked benzophenone percentage amounted to 28-38% for hydrogen, 17-31% for oxygen and 3-28% for nitrogen, the gas permeabilities showed another sharp decline. Gas permselectivity increased significantly with the progress of photocrosslinking, and it can be adjusted in a wide range by controlling the extent of crosslinking. Arrhenius plots of gas permeability for hydrogen and oxygen through UV-irradiated polyimides are straight lines; for nitrogen, however, change in the slope of the straight line is observed and activation energies for hydrogen and oxygen permeation show abrupt increases when crosslinked benzophenone percentage amounts to about 30%. UV-irradiated polyimides with simultaneous high gas permeability and permselectivity make them ideal candidate materials for gas separation. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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