Abstract
Ultraviolet/visible absorption spectra and fluorescence spectra of transparent polyimides derived from 2, 3, 5-tricarboxycyclopentylacetic acid dianhydride (TCAAH) with an aromatic diamine, 4, 4′-diaminodiphenylmethane (DPM), a fluorinated diamine, 2, 2 bis(4-diaminodiphenyl)hexaflu-oropropane (6FdA), and an alicyclic diamine, 4, 4′-diaminodicyclohexylmethane (DCHM) were investigated, as well as their thermal properties. All polyimide films derived from TCAAH showed high transparency in the visible region, i. e., no absorption tail was found above 330nm. The absorption shoulders at 248nm of PI(TCAAH/DPM) and PI(TCAAH/6FdA) are due to the absorption of phenyl groups in the diamine moieties. The fluorescence spectra of all polyimide films studied showed the existence of ground-state complexes. Their excitation wavelength dependence would be due to the existence of various conformation of packing structure. The glass transition temperature, Tg, of these polyimides based on TCAAH lies in the region of 251 to 336°C. These polyimides have main decomposition temperature in the region of 427 to 457°C under the deaerated condition.
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