Chemistry Reference
In-Depth Information
Scheme 1. Poly(amic acid) structures: PAA2 from methylenedianthranilic acid and isophthaloyl-
chloride; PAA from PMDA and ODA.
2.3. Measurements
Metal (M) content was determined as follows: M/PAA2 film was burned at 500-
600°C and the residue was dissolved in HCl solution. The resulting solution of
metal was photocolorimetrically analyzed to determine the amount of metal. Con-
tent of potassium during KOH treatment of PAA2 film was determined by the re-
verse titration method.
IR spectra were recorded on Jasco 810 spectrometer.
Surface electrical resistivity was measured by the two-probe technique with
electrodes in contact with the metalized surface of PI film.
Reflectivity spectra were recorded on IR-65V spectrometer. Scanning elec-
tronic microscopy (SEM) and X-ray fine diffraction (XRFD) analyses were carried
out on an “SEM-Cambridge 5.360 Instruments” microscope. X-ray diffractometry
was recorded with a diffractometer “Zeifert analysis”.
3. RESULTS AND DISCUSSION
3.1. Heterogeneous chelation of PAA2 films
Surface modification of PI films is widely used to enhance incorporation of metal
atoms into the films [19, 20]. One of the main chemical modification routes is hy-
drolysis of polyimide followed by exchange of K
+
ions by Pd
2+
cations. This step
of metallization process is the most important because it determines the quality
and adhesion properties of final metal coating. It is well known that sodium or po-
tassium polyamate dissolves in alkali solutions and fmal hydrolysis represents it-
self as an equilibrium process of polyimide → polyamate chemical conversion
and “washing away” of modified layer. Moreover, PI surface is characterized by
well developed system of mesoporous structure formed during the second step of
PI formation (transformation of poly(amic acid) film into polyimide with elimina-
tion of water and solvent). The diameter of the porous channels achieved is 15-
20 nm which increases during hydrolysis in 3M KOH aqueous solution up to 20-
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