SOME ASPECTS OF PREPARATION OF FLUORINE-CONTAINING POLYIMIDES

Polyimides based on 4,4'-(hexafluoroisopropylidene)diphthalic anhydrid e and 4,4'-(hexafluoroisopropylidene)dianiline with controlled and unc ontrolled molecular weight were prepared. The products with controlled molecular weight were terminated with 4-tert-butylaniline. The synthe sized poly(amic acid)s were transformed into polyimides using both the rmal solid state and solution imidization. Molecular parameters of the prepared polymers were evaluated by viscometry, size exclusion chroma tography and n.m.r. spectroscopy. The properties of polyimides prepare d by both methods were compared. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.