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CT Fluorescence And Molecular Aggregation Of A Polyimide As Function Of Imidization Condition.

Published online by Cambridge University Press:  15 February 2011

M. Hasegawa ,
H. Arai ,
K. Horie ,
R. Yokota  and
I. Mita
M. Hasegawa
Affiliation:
Toho University
H. Arai
Affiliation:
Toho University
K. Horie
Affiliation:
The University of Tokyo
R. Yokota
Affiliation:
Institute of Space and Astronautical Science
I. Mita
Affiliation:
Dow Corning Japan, Ltd.
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Abstract

The emission mechanisms of solid PI(BPDA/PDA) derived from biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA) were examined with the absorption and fluorescence. spectra of model compounds (denoted by M). M(BPDA/CHA) (CHA: cyclohexyl amine) fluoresces at ca. 430 nm in hexafluoro-2-propanol(HFP) solution, while M(BPDA/AN) (AN: aniline) does not. PI(BPDA/PDA) film does not show the monomer fluorescence of biphenyldiimide unit, but shows only intermolecular CT fluorescence peaking at 530–540 nm. This suggests that for PI(BPDA/PDA) film and PI(BPDA/AN) in solution the local excited state of biphenyldiimide units is deactivated owing to intramolecular charge-transfer(CT).

The intermolecular CT fluorescence reflecting sensitively molecular packing of PI chains was used to monitor isothermal imidization process of poly(amic acid)(PAA) of BPDA/PDA. The fluorescence of PAA(BPDA/PDA) peaking at 490 nm decreases rapidly and disappears at 30–40% conversion, then the fluorescence of PI(BPDA/PDA) peaking at 540 nm increases gradually during isothermal imidization. The fluorescence intensity at 540 nm increases rapidly as imidization proceeds when imidized at higher temperature. A kinetic study on isothermal imidization shows that the vitrification is strongly related to the reorientation of polymer chains and the final PI structures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 227: Symposium J – Materials Science of High Temperature Polymers for Microelectronics , 1991 , 125
Copyright
Copyright © Materials Research Society 1991

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References

REFERENCES

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