Study on the structure and adhesion of copper thin films on chemically modified polyimide surfaces - Polyimides and Other High Temperature Polymers - page 333

N-phenylphthalimide, was employed as a model to react with EDA or hydrazine.
This is because the reflective IR spectroscopy does not have enough sensitivity to
detect the imide ring-opening products if their concentrations are far lower than
the polyimide background. The reaction took place very fast under the reaction
conditions (by mixing the imide with 55 vol% of hydrazine aqueous solution at
50 o C or 55 vol% of EDA aqueous solution at 80 o C for 1 minute). The FTIR spec-
tra of the products and N-phehylphthalimide are shown in Figure 2. The pristine
N-phenylphthalimide structure shows the following characteristic peaks: 1776 cm -1
(w) being the asymmetric stretching vibration of the two carbonyl groups in the
imide ring and 1418 cm -1 and 1175 cm -1 peaks belonging to the asymmetric vibra-
tion of the C-N-C bond in the imide ring. The peak at 1710 cm -1 (s) appearing in
all the three spectra is characteristic of the stretching vibration of carbonyl group.
In addition, new peaks appearing at 3260-3280 cm -1 , 1640 cm -1 and 1540 cm -1 in
both (b) and (c) spectra belong to the amide groups generated. On the other hand,
the fact that the intensities of the peaks at 3280, 1640 and 1540 cm -1 in spectrum
(b) are stronger than the corresponding ones in spectrum (c) suggests that hydra-
zine reacts more rapidly than EDA with N-phenylphthalimide even at lower reac-
tion temperature. The FTIR results support the reactions proposed in Figure 1.
Figure 2. FTIR spectra of (a) pristine N-phenylphthalimide (b) the product from the reaction with
hydrazine and (c) the product from the reaction with EDA.