Chemistry Reference
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aqueous solution - leads mainly to formation of black precipitate, most likely as
thin dispersed metal phase with particle size 1-2 nm [16]. Heterogeneous chemi-
cal reduction of a metal in the bulk of a polymer matrix can result in electrocon-
ductive or reflective films and this is what makes this type of metallization very
promising.
A combination of these two approaches is presented in reference [17]. Modi-
fied films obtained by homogeneous doping of poly(amide imide)s solution in
amide solvent by transition metal salts were reduced in an aqueous solution of so-
dium borohydride. Thus metallized poly(amide imide) films exhibited low resis-
tivity, around 1-10 Ω/sq and surface morphology was not uniform.
In this work we present formation of a metal phase by carrying out in situ
chemical reactions in modified polyimide films, as well as results of investigation
of their structure and physical properties.
2. EXPERIMENTAL
2.1. Materials
Isophthaloylchloride was prepared according to reference [18] with M.p. 43°C.
Neutralization equivalent was determined by saponification followed by potenti-
ometric titration of excess alkali by acid solution and was found to be 101.2
(calculated 101.5).
Methylenedianthranilic acid was prepared from o-aminobenzoic acid and for-
maldehyde according to reference [18]. Neutralization equivalent determined by
reverse titration was found to be 143.5 (calculated - 143.5).
Metal salts AgNO
3
, AgAc, CuAc
2
, CuCl
2
, Cu(NO
3
)
2
, CoAc
2
, CoCl
2
, Co(NO
3
)
2
,
NiAc
2
NiCl
2
, Ni(NO
3
)
2
and reducing agent NaBH
4
were used as received from
Aldrich.
Polyimide films Kapton® HN & JP (from DuPont de Nemours) and Upilex S®
(from Ube) were used after washing with aqueous detergent solution and ther-
mally treated at 200°C for 1 hour.
Synthesis of poly(amic acid) based on isophthaloylchloride and methylenedian-
thranilic acid (PAA-2) was carried out by the reaction of equimolar amounts of
methylenedianthranilic acid and isophthaloylchloride in N-methyl-2-pyrrolidone
in an inert atmosphere for 2 hours. Films were cast from PAA2 - see Scheme 1
below, solution and dried at room temperature under vacuum. Neutralization
equivalent was determined to be 208.1 (calculated 208.1).
2.2. Modification of polyimide films
Hydrolysis of polyimide films was carried out in aqueous, alcohol and alcohol-
aqueous solutions of KOH or NaOH. Chelation was carried out by immersion of
hydrolyzed films into an aqueous solution of metal salt. Reduction of the chelated
films was carried out in an aqueous solution of NaBH
4
.
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