Synthetic
Metals
71 (1995) 2097-2098
Stability and transferability of monolayers of polyamic acid salts
Giyoong Tae, Sung-Mog Kim , Young-MO Koo, Jong-Duk Kim and Kyu-Jong Lee*
Department
of Chemical Engineering,
373-l) Kusong-dong,Yusong-gu,
KAIST,
Taejon, 305-70 1, Korea
*Samsung Electronic Devices Co.
575, Shin-Ri, Taean-Eub,
Abstract
The stabilities
The stability
and transferabilities
ofmonolayer increases
as a Y-type on various substrates,
of monolayers
Hwasung-Kun,
Kyungki-Do,
for the two kinds of polyamic acid alkylamine
as the chain length of salts increases. At well-balanced
chain
length
pressure,
ln spite of the advantages
the inherent
layered
films.
assemblies
of the Langmuir-Blodgett
thermal
limitation
this problem
range of the side-chain
of the polymers[‘l.
for producing
and fragility
the applicability
to resolve
from the melting
(long alkyl chains)
conditions
instability
have restricted
The use of polymers
Here,
(LB)
the Langmuir film is transferred
of the
of dimethyl
alkylamines.
the area changes
At
of monolayers
Figure 2, and it reveals clear difference
18 and DMC 13. The rapid decrease
of the LB
of the unstable
also has a
There might be a slight dissolution
state of the monolayer
constant
were
between
surface
measured
in
DMC 16, DMC
of the area is the evidence
at the air-water
into subphase.
interface.
From Figure 2,
it can be concluded that DMC 18 makes a more stable monolayer
segments
we report
stable and homogeneous
polyamic acid salts, precursors
salts (PAAS) were investigated.
condition,
and the thickness of one layer of PAAS was found to be about 16.7 A..
1. INTRODUCTION
method,
Korea, 445-970
the
LB tihns of
than DMC
stabilities
16.
For the PAAS
of the monolayers
formed
from
SE-l 50,
the
showed similar behaviors.
for fonning polyimide LB films.
2. EXPERIMENTAL
ln order to form monolayers
of polyamic acid(PAA) which is
not an amphiphilic, it is treated with alkylamines and obtained
the polyamic acid salts (PAAS). Two kinds of PM
were
primarily used in this experiment.
Pyromettalic
oxydianilline
SE- 150 (Nissan Co.) and three
(PMDA-3,3’-ODA),
kinds of commercial
alkylamine
to PAA : N,N-dimethyl
dianhydride
wes used in stoichiometric
tridecylamine
(DMC
-3,3ratios
13), N,N-dimethyl
hexadecylamine
(DMC 16), and N,N-dimethyl
octadecylamine
(DMC 18). PM was prepared as a solution of 2 mmol/L, diluted
with a mixed
solvent
of benzene
for PMDA-3,3’-ODA
The PAA solution
and N,N-dimethyl
and N,N-dimethylacetamide
was treated
with alkylamine
formamide
Figure 1. K-A isotherms
of PAAS of PMDA-3,3’-ODA
for SE-l 50.
to produce
1
mmol/L solution of PAAS, and the stability of the monolayer
at
air-water interface were determined. After transfer, the thickness
of the LB tihns on the substrate is identified by the ellipsometry
and XRD.
The prevailing
tendency
of transfer
started like Y-type deposition,
3. RESULTS
Figure I shows the T-A isotherms of PAAS of PMDA-3,3’ODA. The collapse pressure increases by increasiue the alkyl
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of PAAS of PMDA-3,3’-
ODA onto the ITO-glass is the Z-type(Figure 3). So, the first
deposition was carried out in the upward direction for all cases.
With DMC 13, the film was transferred as the Z-type up to 8
layers, but no further transfer was observed.
With DMC 16, it
but soon changed
into a Z-type
deposition.
But, when DMC 18 was used, a Y-type deposition
was maintained, although the transferred area at the downward
stroke is smaller than that at the upward stroke
2098
G. Tae et al. / Synthetic MetaLr 71 (1995) 2097-2098
01”’
12
0
,000
2000
3000 4000
The (UC)
5000
6000
7000
at constant surface pressure
3,3’-ODA) according to the length of alkylamine
increased,
characteristic
the transferability
onto the ITO-glass
As the surface
was also improved,
above 2.5 mN/m, there were little differences
but
in transferabilities.
Very high surface pressure often yields
unstable transferred
films, so 25 mN/m was chosen for the following experiments.
Generally,
PAAS of SE-150 was well transferred
while a Z-type deposition
Such change be inherited
of DMC
was observed
as a Y-type,
for using DMC 161*1.
from the chain length, DMC 18, instead
16, is more effective
in adjusting
balance, as well as the characteristics
the amphiphilic
of the given polyamic acid.
To examine the regularity of the LB film ellipsometry
measurement
ellipsometric
was
carried
thickness
out.
Figure
of LB films
6
7
.9
9
Cigar
of PAAS( SE- 150) LB
4. CONCLUSION
of PAAS of SE-150 for various surface pressures.
pressure
5
Figure 5. Thickness measurement
films by ellipsopmety
area of PAAS(PMDA-
(dipping speed = 10 mm/min)
Figure 4 shows the transfer
4
Figure 4. Transfered area PAAS(SE-150) with DMC 18
for various surface pressure onto ITO-glass
Figure 2. Area changes of PAAS of PMDA-3,3’-ODA
Figure 3. The change of transfered
3
No. of Dapo&im
,I
5
increases
shows
and XRD
that
the
with the given
number of layers, and such a regularity was confirmed by XRD
measurement. The thickness of a single layer is 16.7 A.
Monolayers
of PAAS from SE-150,
PMDA-3,3’-ODA
The PAAS of PMDA-3,3’-ODA
characteristic,
as well as PAAS from
were most stable when DMC
so the upward-first
was transferred
deposition
18 was added.
with a Z-type
was more effective.
But, the transfer could be improved by lengthening
the alky chain
length of alkylamine
At low surface pressure, the transfer of
PAAS of SE-150 increases as the surface pressure increased, but
above 25 mN/m,
there was no significant
transferred
as a Y-type
onto various
thickness
of the PAAS
of SE-150
ellipsometry
effect.
substrates.
was
about
It was well
One
layer
16.7 A.
and XRD measurement.
REFERENCES
1. Gerhard Wegner, Thin Solid Films, 2 16 ( 1992), 105
2. MKakimoto, M.Suzuki, T.Konishi, Y.lmai, M.Iwamoto,and
T.Hino, Chemisty Letters, 823 (1986).
by