Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 0887-624X
    Keywords: aromatic nucleophilic substitution polymerization ; methyl-substituted bisphenols ; aromatic poly (ether sulfone)s ; aromatic poly (ether ketone)s ; thermal behavior ; photo-crosslinking ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel methyl-substituted aromatic poly (ether sulfone)s and poly (ether ketone)s were synthesized from combinations of 3,3′,5,5′-tetramethylbipheny-4,4′-diol and 2,2′,3,3′,5,5′-hexamethylbiphenyl-4,4′-diol, and 4,4′-dichlorodiphenyl sulfone and 4,4′-difluorobenzo-phenone by nucleophilic aromatic substitution polycondensation. The polycondensations proceeded quantitatively in a N-methyl-2-pyrrolidone-toluene solvent system in the presence of anhydrous potassium carbonate to afford the polymers with inherent viscosities between 0.86 and 1.55 dL/g. The methyl-substituted poly (ether sulfone)s and poly (ether ketone)s showed good solubility in common organic solvents such as chloroform, tetrahydrofuran, pyridine, m-cresol, and N,N-dimethylacetamide. The tetramethyl- and hexamethyl-substituted aromatic polyethers had higher glass transition temperatures than the corresponding unsubstituted polymers, and did not decompose below 350°C in both air and nitrogen atmospheres. The films of the methyl-substituted poly (ether ketone)s became insoluble in chloroform by the irradiation of ultraviolet light, indicating the occurrence of photochemical crosslinking reactions. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The microstructure of poly[polytetrahydrofuran-block-poly(sebacoyl chloride-alt-hexamethylenediamine)]s 1-4, containing polytetrahydrofuran (PTHF) blocks of various molecular weights, and their blood compatibility were studied. These multiblock copolymers were prepared by interfacial polycondensation. The characterization of these copolymers was carried out by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), dynamic mechanical measurements, wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and electron spectroscopy for chemical analysis (ESCA). The TEM observation revealed the formation of a spherulitic structure at the copolymer surfaces, which is closely related to the homopolymer, polyamide (PA) 610. The DSC and dynamic mechanical measurements indicate the presence of distinct phase separation between PTHF and PA 610 blocks, and of the PTHF block in the copolymer being partially crystallized. The WAXD and SAXS indicate the formation of microstructures composed of crystalline and amorphous phases in the copolymer. Moreover, ESCA measurements verify that the surface chemical composition of the copolymer is identical to their bulk composition. Blood compatibility of these copolymers was evaluated by estimating platelet adhesion on the copolymer surfaces. Platelet adhesion was found to be affected by the PA 610 crystallinity, including the size and distribution of the crystalline phase in the case of the copolymers in which the PTHF blocks are completely amorphous (M̄n = 980). On the contrary, platelet adhesion at the copolymers in which the PTHF blocks are partially crystallized (M̄n ≥ 1560) depends upon the crystallinity of both PA 610 and PTHF, including the balance of crystalline (PA 610 and PTHF) and amorphous (mainly PTHF) phases. This result suggests that the balance of the crystalline and amorphous phase distribution in the copolymer is the most determinative factor for suppressing platelet adhesion at the copolymer surface.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...