ISSN:
0360-6376
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
A structural study of furan-maleic anhydride copolymer (F-MAH) was undertaken to confirm its alternating nature and to determine its microstructure. The spectral properties of a model compound representing the alternating repeat unit, 2-(2-tetrahydrofuranyl)succinic anhydride, were compared with those of F-MAH. Their infrared (IR), 1H, and 13C nuclear magnetic resonance (NMR) spectra (after compensating for the absence of the olefinic double bond) were in good agreement with those of the copolymer. Furthermore, the observed splitting in the 1H- and 13C-NMR spectra of F-MAH were assigned to cis-trans linkages on both the F and MAH units, with cis linkage being favored on both units, especially the former. The structure of 2,5-dimethylfuran (DMeF)-MAH copolymer is similar to that of F-MAH copolymer, except that the preference of cis linkages is less pronounced. The structure of 2-methylfuran (MF)-MAH copolymer is a complex structure with numerous 2,3-furandiyl units. A mechanistic study was undertaken to elucidate the roles of F-MAH Diels-Alder adduct, and the charge-transfer (CT) complex in the radical initiated copolymerization. The adduct reverted substantially to monomers under the reaction conditions; but, the amount of adduct remaining at equilibrium was quite appreciable; therefore, its participation could be ruled out on this basis alone. However, on polymerizing the adduct in the presence of F-d4, the latter was incorporated into the copolymer to an extent indicative of free monomer exchange. Therefore, the adduct cannot be directly involved in the polymerization.
Zusätzliches Material:
16 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1981.170190514
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