Photosensitivity of polymers based on epoxy-substituted vinylphenylcyclopropanes

Article abstract of DOI:10.1134/S1070427206030323

The capability of polymers synthesized from new monomers, 2-glycidyloxymethyl- and 2-glycidyloxycarbonyl-1-(p-vinylphenyl)cyclopropane, to photochemical cross-linking was evaluated from variation of their solubility after UV irradiation. The dependence of

Full text of DOI:10.1134/S1070427206030323

ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 488 491. Pleiades Publishing, Inc., 2006.
Original Russian Text K.G. Guliev, G.Z. Ponomareva, A.M. Guliev, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3, pp. 497 500.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Photosensitivity of Polymers Based on Epoxy-Substituted
Vinylphenylcyclopropanes
K. G. Guliev, G. Z. Ponomareva, and A. M. Guliev
Institute of Polymer Materials, National Academy of Sciences of Azerbaijan, Sumgaiyt, Azerbaijan
Received August 9, 2005; in final form, November 2005
Abstract The capability of polymers synthesized from new monomers, 2-glycidyloxymethyl- and 2-glycidyl-
oxycarbonyl-1-(p-vinylphenyl)cyclopropane, to photochemical cross-linking was evaluated from variation
of their solubility after UV irradiation. The dependence of the photosensitivity of the polymers on the structure
of substituents was studied.
DOI: 10.1134/S1070427206030323
The prospects for practical use of functional poly-
mers, in particular, in negative photoresists, cause
an interest in their study. The presence of functional
groups and also their chemical nature affect appreci-
ably such important photolithographic parameters
of a resist as photosensitivity and resolution [1 7].
following pathway:
CH2
CH2
CH
CH
ECG
X
R
,
The practice of using some resists in photoli-
thographic processes revealed a number of significant
drawbacks, one of which is low photosensitivity.
Hence, to improve the photosensitivity and other
lithographic characteristics of negative photoresists
based on functional polymers, radically new ap-
proaches to the synthesis of new monomers and poly-
mers based on these are required.
=
where X
CH2 OH, COOH
;
O
R = CH2 OCH2
CH2
C
OCH2
CH
.
CH2
CH
,
O
O
I
II
Chromatographic analysis and spectral data showed
that the synthesized monomers I and II were mixtures
of two individual compounds. We found that these
compounds were geometric cis and trans isomers
(ratio cis : trans = 30 : 70). The purity of the mono-
mers synthesized was monitored by gas-liquid chro-
matography. In all cases it was 99.9%.
We studied previously [8] the photochemical char-
acteristics of polymers of functionally 2-substituted
cyclopropylstyrenes.
Here we studied how the structure of functional
groups affects the photosensitivity of polymers pre-
pared from 2-glycidyloxymethyl- and 2-glycidyloxy-
carbonyl-1-(p-vinylphenyl)cyclopropanes.
In the IR spectra of I and II, there are absorption
bands at 830 850, 990 1000, 1640 1645, 1035
1045, and 1105 1110 cm , characteristic of epoxy
1
ring, vinyl group, three-membered carbon ring, and
The monomer for preparing the polymer was syn-
thesized as follows. First, 2-ethoxycarbonyl-1-(p-vin-
ylphenyl)cyclopropane was prepared by the reaction
of ethyl diazoacetate with p-divinylbenzene in the
ether bond, respectively. In addition, in monomer II
1
there is an absorption band at 1720 cm characteristic
of the carbonyl group. The absorption bands at 1500
1
and 1605 cm characteristic of the benzene ring are
presence of a catalytic amount of anhydrous CuSO .
4
preserved.
Then, 2-ethoxycarbonyl-1-(p-vinylphenyl)cycloprop-
ane was saponified to obtain 2-carboxy-1-(p-vinyl-
phenyl)cyclopropane and reduced to obtain 2-hy-
droxymethyl-1-(p-vinylphenyl)cyclopropane [9].
1
The H NMR spectra of I and II contain signals
characteristic of protons of aromatic ring ( = 6.60
7.30 ppm), cyclopropane ring (0.65 1.66 ppm), and
vinyl group (5.10 6.65 ppm). The epoxy ring protons
To prepare 2-glycidyloxymethyl- and 2-glycidyl-
oxycarbonyl-substituted cyclopropanes, we chose the
give signals at 2.30 2.60 ppm (CH ), and 2.96 ppm
2
488

PHOTOSENSITIVITY OF POLYMERS
489
(CH). These results suggest that the reactions in all
steps proceed smoothly and with quantitative yields of
the target products, leaving the vinyl group and three-
membered ring intact.
Table 1. Data on UV irradiation of polymers based on
monomers I and II
Amount of polymer, %, after irradiation
for indicated time, min
Monomer
Polymerization of I and II was performed in the
bulk and in benzene solution at 70 C in the presence
of azobis(isobutylonitrile) (AIBN).
1
2
6
10
12
I
II
17
23
45
50
65
70
88
91
93
97
It was shown that, under the conditions studied,
polymerization proceeds via scission of the double
bond of the vinyl group to form macromolecules with
reactive cyclopropane and epoxy side groups. This
fact is confirmed by examination of the structure of
the resulting polymers.
radiation. The results of UV irradiation are presented
in Table 1.
Table 1 shows that the maximal degree of photo-
chemical conversion (the maximal amount of in-
soluble fractions) is observed with the polymer ob-
tained from monomer II. This fact is undoubtedly
associated with the structure of the macromolecule:
along with cyclopropane and epoxy groups, it contains
strongly absorbing carbonyl group, which significant-
ly enhances the uptake of the UV energy.
A comparison of the IR spectra of the initial mono-
mers and polymers synthesized from them shows that
the absorption bands at 990 and 1640 cm observed
1
in the spectra of the initial monomers and assigned to
the bending and stretching modes of the vinyl bond,
respectively, disappear after polymerization. The ab-
1
sorption bands at 1500 and 1605 cm and in the
1
range 1035 1045 cm characteristic of the benzene
The spectral analysis of the polymers showed that
after UV irradiation the absorption bands character-
ring and cyclopropane group, respectively, are re-
tained during polymerization.
1
istic of cyclopropane ring (1030 1040 cm ) and
1
The absorption bands in the spectra of polymers at
epoxy fragment (840 850, 917, 1250 1260 cm ) de-
1
1720 and in the ranges 840 850, 1105 1110 cm ,
crease or disappear. It was shown that the intensities
of the absorption bands characteristic of cyclopropane
and epoxy fragments decrease to a similar extent
during UV irradiation in the initial stages. The clearest
results were obtained at irradiation duration of 30 min,
when the absorption bands of the above fragments
virtually completely disappeared. Since the spectrum
of the polymer after irradiation contained no absorp-
tion bands corresponding to cyclopropane and epoxy
rings, it is evident that these groups participate in the
subsequent photochemical reactions and these reac-
tions are apparently resposible for the high capability
of the polymer for photochemical cross-linking.
assigned to vibrations of the C O, epoxy, and ether
groups, are completely retained after the polymeriza-
tion.
The IR data and elemental analysis suggest that the
polymers synthesized have the following structure:
(
)
CH2
CH
CH2
CH
n
AIBN
n
R
R
.
First of all, we should note some features of the
structure of the resulting polymers containing two
reactive groups, cyclopropane and epoxy, in the side
chains of macromolecule. Due to easy rupture of
the C C and C O bonds under irradiation [10 12],
these functional groups impart to the resulting poly-
mers high sensitivity to UV irradiation: under UV ir-
radiation, these polymers easily transform into the
insoluble form.
As seen from Table 2, the polymers synthesized
have high lithographic characteristics, which allows
these polymers to be used as a photosensitive base of
photoresists. Thus, our studies demonstrated the pos-
sibility of developing a new class of photosensitive
materials having high film-forming ability, elasticity,
achromatism, and good adhesion characteristics appro-
priate for formation of photoresist films.
To elucidate the mechanism of photochemical
cross-linking, we performed a spectroscopic study.
For this purpose, we studied cross-linking of the
resulting epoxy and cyclopropane-containing poly-
mers by IR spectroscopy in various stages of UV ir-
EXPERIMENTAL
2-Glycidyloxymethyl-1-(p-vinylphenyl)cycloprop-
ane was prepared in a three-necked flask charged with
14.4 g (0.1 mol) of 2-hydroxymethyl-1-(p-vinylphen-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 3 2006

490
GULIEV et al.
Table 2. Characteristics of polymers based on epoxy-substituted vinylphenylcyclopropanes
Copoly-
mer
Concentration of poly-
mer in benzene, %
Content of micro-
defects, def cm
Film thick-
ness,
Exposure
time, s
Photosensitivity,
2
1
m
cm2 J
I
2
5
6
10
2
5
0.20
0.20
0.20
0.25
0.15
0.15
0.20
0.20
0.15
20
20
20
20
20
20
20
20
55.8
56.7
52.3
50.5
56.4
58.4
53.2
51.7
0.15
0.15
0.20
0.15
0.15
0.15
0.15
II
6
10
yl)cyclopropane in 50 ml of dehydrated ethanol, 0.2 g
of hydroquinone, and 8 g (0.2 mol) of powdered sodi-
um hydroxide. Then, 14 g (0.15 mol) of epichlorohy-
drin (ECH) was added with vigorous stirring. The
reaction mixture was stirred for 4 h. The NaCl precipi-
tate was filtered off, and ethyl ether was removed.
Then the reaction mixture was distilled to isolate
the reaction product: bp 150 153 C at 1 mm Hg,
After purification, all the polymers obtained are
soluble in aromatic and chlorine-containing hydrocar-
bons and insoluble in alcohols.
The molecular weight was estimated from the
intrinsic viscosity determined in benzene in an Ub-
1
belohde viscometer: [ ] = 1.05 (I) and 1.1 dl g (II).
The IR spectra of the polymers were recorded
on a UR-20 spectrometer.
20
20
yield 18.86 g (82%), n = 1.5220, d = 1.04,
D
4
MR
/MR
= 67.07/67.45.
To study the photochemical cross-linking of poly-
mers, we prepared 2 10% solutions of polymers,
which were applied to a glass support (K-8) 60
90 mm in size by centrifugation at 2500 rpm. The
thickness of the resulting resist film was measured
with an MII-4 Linnik microinterferometer. It was
0.15 0.20 m.
Dcalc
Dfound
Found (%): C 78.30, H 7.80.
Calculated (%): C 78.26, H 7.83.
2-Glycidyloxycarbonyl-1-( p-vinylphenyl)cyclo-
propane was prepared in a three-necked flask equipped
with a stirrer, a reflux condenser, and a dropping
funnel. The flask was charged with 18.8 g (0.1 mol)
of 2-carboxy-1-(p-vinylphenyl)cyclopropane, 50 ml of
anhydrous ether, and 1.2 g of hydroquinone, and 2.3 g
(0.1 g-atom) of finely cut sodium metal was added
with stirring in a nitrogen atmosphere. After complete
dissolution of sodium, 14 g (1.15 mol) of ECH was
added dropwise. The mixture was heated to 40 C for
1 h; after reaction completion, NaCl was filtered off,
and the ether and unchanged EPC were removed. The
residue was distilled in a vacuum; bp 160 162 C at
The layer was dried for 10 min at room tempera-
ture and for 20 min at 40 45 C at a pressure of
10 mm Hg.
A DRT-220 mercury lamp (current strength 2.2 A)
was used as a UV source, the distance from the radia-
tion source was 15 cm, the velocity of moving the
1
exposure meter gate was 720 mm h , and the ex-
posure time was 5 20 s. The content of insoluble
polymer was determined from the ratio of the polymer
weight to the initial weight of the film.
20
20
1 mm Hg, yield 22.21 g (91%), n = 1.5310, d
=
D
4
1.12, MR
/MR
= 67.09/67.36.
Dcalc
Dfound
CONCLUSION
Found (%): C 78.30, H 7.80.
Calculated (%): C 78.26, H 7.83.
New monomers, 2-glycidyloxymethyl- and 2-gly-
cidyloxycarbonyl-1-(p-vinylphenyl)cyclopropane, and
polymers based on these were synthesized and charac-
terized. The photosensitivity of the resulting polymers
and its dependence on the substituent structure were
studied. Participation of cyclopropane and epoxy
groups in photochemical cross-linking was estab-
lished.
Polymerization was carried out both in the bulk and
in a benzene solution in the presence of 0.2 mol %
AIBN at 70 C. The resulting polymers were purified
by twofold precipitation from a benzene solution
with methanol and dried at 30 C in a vacuum (15
20 mm Hg).
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PHOTOSENSITIVITY OF POLYMERS
491
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