Handbook of Solvents - George Wypych - ChemTech - Ventech!

13.4 Effect of polymerization solvent 843
Figure 13.4.1 IR spectra of PAAA-1, PAI-1, and PAI-3
[Data from reference 7]
signed to benzene nuclei that is stable to heat treatment.
IR spectra of PAAA-1 show absorptions
at 1530 and 1660 cm -1 , which are characteristic
of amide bond, 1510 and 1590
cm -1 which are characteristic of benzene nuclei,
and 1230 cm -1 , which is characteristic
of ether bond, but the absorption at 1380
and 1780 cm -l , which are characteristic of
imide bond, are hardly observed. On the
other hand, IR spectra of PAI-1 and PAI-3,
obtained by heating of PAAA-1 and
PAAA-3, respectively, show new absorptions
at 1380 and 1780 cm -1 .
Among the adsorptions of imide bond,
the absorption at 1380 cm -1 is assigned to
C-N stretching vibrations of all imide bond
(cyclic and acyclic imide bond as shown in
Eq. [ 13.4.3 ] and 1780 cm -1 is assigned to
C=O stretching vibrations of five-member
imide rings (cyclic imide bond). The absorption
at 1530 cm -1 is assigned to N-H
stretching vibrations of amide bond. Furthermore,
the absorption at 1510 cm -1 is as-
Therefore, the content of cyclic imide, amide and all imide bond of PAI was estimated
by the absorbance ratio, D 1380/D 1510 (the absorbance ratio of absorbance at 1380 cm -1 to that
of benzene nuclei), D 1780/D 1510, and D 1530/D 1510, respectively.
Table 13.4.2 shows the absorbance ratio of cyclic imide, amide, and all imide bond before
and after heat treatment of PAAAs. The considerable increase of cyclic and all imide
bond content of PAAAs and the decrease of amide bond were observed by heating. But the
effect of solvent on the imidation of PAAAs was hardly observed.