Synthesis and copolymerization study of new polyimide precursors with potential application in optical and photonic field

Article abstract of DOI:10.1080/15421400801917338

New polyimide precursors were synthesized by simple one step procedure. (Z)-3-(4-Nitro-phenylcarbamoyl)-acrylic acid (A2), (Z)-3-(4-Ciano- phenylcarbamoyl)-acrylic acid (A3), (Z)-3-(4-Diethyl-phenylcarbamoyl)-acrylic acid (A4) and (Z)-3-[N'-(2,4-Dinitro-phenyl)-hydrazinocarbonyl]-acrylic acid (A6) were characterized by FT-IR, FT-NMR and UV-VIS spectroscopy. Test copolymerization successfully yielded copolymers that were characterized by FT-IR and FT-NMR spectroscopy. Improved solubility of these copolymers make them candidates for potential NLO applications.

Full text of DOI:10.1080/15421400801917338

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Synthesis and
Copolymerization Study of
New Polyimide Precursors with
Potential Application in Optical
and Photonic Field
Adriana Florica Nicolescu a , Victor Valentin Jerca
a , Ana-Maria Albu a b , Dumitru Mircea Vuluga a
Constantin Draghici a
&
a Centre for Organic Chemistry Costin D. Nenitescu,
Romanian Academy , Bucharest, Romania
b University “POLITEHNICA” of Bucharest
Department of Polymer Science , Calea Victoriei,
Bucharest, Romania
Published online: 22 Sep 2010.
To cite this article: Adriana Florica Nicolescu , Victor Valentin Jerca , Ana-
Maria Albu , Dumitru Mircea Vuluga & Constantin Draghici (2008) Synthesis and
Copolymerization Study of New Polyimide Precursors with Potential Application
in Optical and Photonic Field, Molecular Crystals and Liquid Crystals, 486:1, 38/
[1080]-49/[1091], DOI: 10.1080/15421400801917338
To link to this article: http://dx.doi.org/10.1080/15421400801917338
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Mol. Cryst. Liq. Cryst., Vol. 486, pp. 38=[1080]–49=[1091], 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 1542-1406 print=1563-5287 online
DOI: 10.1080/15421400801917338
Synthesis and Copolymerization Study of New
Polyimide Precursors with Potential Application
in Optical and Photonic Field
Adriana Florica Nicolescu1, Victor Valentin Jerca1,
Ana-Maria Albu1,2, Dumitru Mircea Vuluga1,
and Constantin Draghici1
1Centre for Organic Chemistry Costin D. Nenitescu, Romanian
Academy, Bucharest, Romania
2University ‘‘POLITEHNICA’’ of Bucharest Department of Polymer
Science, Calea Victoriei, Bucharest, Romania
New polyimide precursors were synthesized by simple one step procedure. (Z)-3-
(4-Nitro-phenylcarbamoyl)-acrylic acid (A2), (Z)-3-(4-Ciano-phenylcarbamoyl)-
acrylic acid (A3), (Z)-3-(4-Diethyl-phenylcarbamoyl)-acrylic acid (A4) and (Z)-3-
[N0-(2,4-Dinitro-phenyl)-hydrazinocarbonyl]-acrylic acid (A6) were characterized
by FT-IR, FT-NMR and UV-VIS spectroscopy. Test copolymerization successfully
yielded copolymers that were characterized by FT-IR and FT-NMR spectroscopy.
Improved solubility of these copolymers make them candidates for potential
NLO applications.
Keywords: aniline derivatives; copolyimide; NLO potential; polyimide solubility
INTRODUCTION
Aromatic polyimides are known for their excellent thermooxidative
stability, electrical properties and chemical resistance. Due to these
characteristics such polymers are widely used in various applications
[1–4]. However, most of the aromatic polyimides have more than one
The financial support of the Romanian Ministry of Education and Research, by
means of projects Ceex MENER 703-HYPROD, CEEX CERES 19-ORGFOTON, CEEX
AMCSIT 56-ECOTEXIZ and CEEX AMCSIT 61-BICOP, for achieving this contribution
is gratefully acknowledged.
Address correspondence to Adriana Florica Nicolescu, Centre for Organic Chemistry
Costin D. Nenitescu, Romanian Academy, 202B. Spl. Independentei CP 35-108,
Bucharest 060023, Romania. E-mail: adinicolescu@cco.ro
38=[1080]

New Polyimide Precursors with NLO Potential
39=[1081]
drawback, like their intractability in fully imidized form [5] or their
insolubility in usual solvents, sources of major difficulties in proces-
sing. Therefore, the preparation of new monomers and redesigned sol-
uble, thermoplastic copolyimides recently attracted great interest.
Using copolymerization as a method for improving the polymer
properties represents an alternative way to overcome processing dis-
advantages and meet specific requirements.
Polymers with high nonlinear optical (NLO) properties are of major
interest in developing electro-optic and photonic devices. In order to be
useful in optical device applications, the synthesized materials should
have a stable response at elevated temperatures and good chemical
and physical stability as well [6].
In this article, four novel maleiamic monomers, (Z)-3-(4-Nitro-
phenylcarbamoyl)-acrylic acid (A2), (Z)-3-(4-Ciano-phenylcarbamoyl)-
acrylic acid (A3), (Z)-3-(4-Diethyl-phenylcarbamoyl)-acrylic acid (A4)
and (Z)-3-[N0-(2,4-Dinitro-phenyl)-hydrazinocarbonyl]-acrylic acid
(A6), were prepared from maleic anhydride with p-nitro-aniline,
p-amino-bezonitrile, N,N-diethyl-p-amino-aniline and 2,4-dinitro-
phenylhydrazine, respectively.
The article presents the synthesis and characterization of four new
maleiamic monomers, the reactivity in radical copolymerization of (Z)-
3-[N0-(2,4-Dinitro-phenyl)-hydrazinocarbonyl]-acrylic acid (A6) with
styrene (St) and chloromethylstyrene (CMS) as well as the character-
ization of the obtained copolymers.
EXPERIMENTAL
Materials
Maleic anhydride (Aldrich) was recrystallized from chloroform.
p-Amino-bezonitrile (Fluka, 97% pure), p-nitroaniline (Merck, for syn-
thesis), N,N-diethyl p-aminoaniline (Fluka, purum), p-aminobenzoic
acid (Merck, for synthesis) and 2,4-dinitrophenylhydrazine (Merck,
for synthesis) were used as received. CMS (Aldrich) was used as sup-
plied. St was purified by distillation under reduced pressure before
using. AIBN (2,20-azo-bis-isobutyronitrile, Aldrich) was recrystallized
from methanol and benzoyl peroxide (PB, Aldrich) was used as sup-
plied. Dimethyl formamide (DMF), dioxane, methanol (Merck, analyti-
cal grade) were dried according to standard procedure [7].
Measurements
The UV-VIS spectra for the monomers were taken in THF (thetrahy-
drofuran) with a Varian Carry 100 Spectrometer. 1H-FT-NMR spectra

40=[1082]
Adriana Florica Nicolescu et al.
of monomers and copolymers samples were taken at 400 MHz and
13C-FT-NMR spectra were recorded at 100 MHz in DMSO-d6 (dimethyl
sulfoxide) on a Varian Unity 400 Spectrometer. FT-IR spectra of mono-
mers and copolymers samples were recorded on a Bruker Vertex 70
Spectrometer fitted with Harrick MVP 2 diamond ATR device.
Preparation of (Z)-3-(4-Carboxy-phenylcarbamoyl)-acrylic
Acid (A1)
The A1 monomer was synthesized in a one step reaction from maleic
anhydride and p-amino-benzoic acid (Scheme 1a) [8].
The solution of maleic anhydride (2.46 g, 0.025 mole) in DMF was
gradually added while stirring, over a period of 10 min, to a solution
of p-nitro-aniline (3.4 g, 0.025 mole) in DMF. The solution was stirred
for 2 h at room temperature. The resulting solution was poured into
crushed ice to precipitate crude A1. The crude A1 was filtered, dried
and then recrystallized from methanol.
The FT-IR spectrum showed absorptions at 3500–2500 (carboxylic
acid OꢀH), 3313, 1575, 1504 (amide NꢀH), 1682 (carboxylic acid
=
and amide), 1289 (carboxylic acid CꢀO), 844 (CH CH), 673 (CꢀH
bending), all in cmꢀ1.
SCHEME 1 Synthetic route for the new monomers.

New Polyimide Precursors with NLO Potential
41=[1083]
Preparation of (Z)-3-(4-Nitro-phenylcarbamoyl)-acrylic
Acid (A2)
The A2 monomer was synthesized in a one step reaction from maleic
anhydride and p-nitro-aniline (Scheme 1b). The procedure for sample
A2 remains the same as before, maintaining the same molar ratio of
1:1 between the two reagents.
FT-IR: 3500-2500 (carboxylic acid OꢀH), 3293, 1547, 1510 (amide
NꢀH), 1704 (carboxylic acid and amide), 1305 (carboxylic acid CꢀO),
ꢀ1
=
849 (CH CH), 685 (CꢀH bending), all in cm .
Preparation of (Z)-3-(4-Ciano-phenylcarbamoyl)-acrylic
Acid (A3)
The A3 monomer was synthesized in a one step reaction from maleic
anhydride and p-amino benzonitril (Scheme 1c). The synthesis for
monomer A3 was carried out under identical conditions as A1.
FT-IR: 3500-2500 (carboxylic acid OꢀH), 3330, 1492 (amide NꢀH),
1643 (carboxylic acid and amide), 1299 (carboxylic acid CꢀO), 855
ꢀ1
=
(CH CH), 617 (CꢀH bending), all in cm .
Preparation of (Z)-3-(4-Diethyl-phenylcarbamoyl)-acrylic
Acid (A4)
The A4 monomer was synthesized in a one step reaction from
maleic anhydride and p-amino-N,N-diethyl-aniline (Scheme 1d). The
procedure for sample A4 remains the same as before.
FT-IR: 3500-2500 (carboxylic acid OꢀH), 3275, 1514, 1464 (amide
NꢀH), 1690 (carboxylic acid and amide), 1257 (carboxylic acid CꢀO),
ꢀ1
=
844 (CH CH), 619 (CꢀH bending), all in cm .
Preparation of (Z)-3-[N0-(2,4-Dinitro-phenyl)-
hydrazinocarbonyl]-acrylic Acid (A6)
The A6 monomer was synthesized in a one step reaction from maleic
anhydride and 2,4-dinitrophenylhydrazine (Scheme 1e). The pro-
cedure for sample A6 is the same, only this time the reaction is
conducted at a temperature of 50ꢁC.
FT-IR: 3500-2500 (carboxylic acid OꢀH), 3293, 1547, 1510 (amide
NꢀH), 1704 (carboxylic acid and amide), 1305 (carboxylic acid CꢀO),
ꢀ1
=
849 (CH CH), 685 (CꢀH bending), all in cm .

42=[1084]
Adriana Florica Nicolescu et al.
Copolymerization
The copolymerization of CMS and A6 was carried out at 70ꢁC for 4 h in
a round bottom flask with a reflux condenser, employing calculated
amounts of comonomers in 50 ml dioxane with 0.0115 g AIBN
(Scheme 2b). The 2nd copolymerization of St with A6 was performed
in concentrated solution of DMF initiated with 0.0121 g of PB at
60ꢁC for 4 h also (Scheme 2a). The copolymers were precipitated in
methanol-petroleum ether mixture. After dissolving the crude copoly-
mers in dioxane they were precipitated again in an excess quantity of
methanol-water mixture. The purification process was repeated twice,
and then the copolymers were dried at 60ꢁC under vacuum for 48 h.
SCHEME 2 Synthetic route for the copolymers.

New Polyimide Precursors with NLO Potential
43=[1085]
RESULTS AND DISCUSSION
Solubility Behaviour
All the synthesized monomers are soluble in acetone, dioxane, THF,
DMF, DMSO; partially soluble in dichloromethane and chlorobenzene
and insoluble in chloroform, ethyl ether, petroleum ether, at room
temperature.
Spectral Characterization of Synthesized Monomers
All FT-IR and FT-NMR spectra (see Figs. 2–7) are supporting the
structures of the monomers that we proposed. All NMR signals
attributions are shown in Tables 2 and 3 for all the synthesized mono-
mers. From the UV-VIS spectra (see Fig. 1) of the four novel monomers
we calculate the molar extinction coefficients (e) listed in Table 1.
Spectral Characterization for the Copolymers
The FT-IR spectra reveal the presence of absorption bands at 1872 and
1722 cmꢀ1 due to stretching of C O (nCH; nCOOH) from the maleiamic
=
ring of A6 in St-A6 copolymer, which confirms the gradual insertion
of the maleiamic acid, (other characteristic vibrations are 694 cmꢀ1
FIGURE 1 The UV-VIS spectra for A3 monomer.

44=[1086]
Adriana Florica Nicolescu et al.
FIGURE 2 1H-FT-NMR spectra for A1 monomer.
FIGURE 3 1H-FT-NMR spectra for A2 monomer.
FIGURE 4 13C-FT-NMR spectra for A2 monomer.

New Polyimide Precursors with NLO Potential
45=[1087]
FIGURE 5 13C-FT-NMR spectra for A3 monomer.
(cCH), 2921 (nCH and nNH) and 2849 (nCH)) as shown in Figure 8. CMS-
A6 copolymer shows absorption bands at 1872 and 1722 cmꢀ1, and
other important stretching bands can be observed at 1264 cmꢀ1
(CH2Cl), 3128–3026 cmꢀ1 (nCH; nCOOH), 2921 (nCH and nNH), 2849
(nCH).
1
From the H-NMR spectra of the A6-CMS and A6-St copolymers,
the A6 comonomer insertion could be evaluated, the molar ratio
between the two comonomers depending on the reactive comonomer
as follows: CMS=A6 ¼ 1=0.45 and St=A6 ¼ 1=0.2.
FIGURE 6 13C-FT-NMR spectra for A4 monomer.

46=[1088]
Adriana Florica Nicolescu et al.
FIGURE 7 13C- FT-NMR spectra for A6 monomer
CONCLUSIONS
Four new monomers were synthesized and their structure was
confirmed by FT-IR and FT-NMR spectra. The monomers showed
excellent solubility in acetone, dioxane, THF, DMF and DMSO. Test
radical copolymerization of (Z)-3-[N0-(2,4-Dinitro-phenyl)-hydrazino-
carbonyl]-acrylic acid (A6) was successfully attempted with two
different reactive comonomers. The copolymers were characterized
TABLE 1 Spectral and Physical Characteristics of the
Synthesized Monomers
Monomer code
Yield (%)
Wave length (nm)
e (l=mol cm)
A1
A2
17
34
—
—
88853
8835
260
358
259
315
260
319
261
454
A3
A4
A6
52
28
85
8586
155031
25808
25882
54229
59171

47=[1089]

48=[1090]

New Polyimide Precursors with NLO Potential
49=[1091]
FIGURE 8 FT-IR spectra for the the synthesized copolymers.
1
by FT-IR and H-FT-NMR spectroscopy. The successful insertion of
synthesized compound in copolymer chain proves that these
monomers can be used for designing materials with potential NLO
applications.
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Blackie: Glasgow, U.K.
[4] Scroog, C. E. (1976). J. Polym. Sci. (Macromol. Rev.), 11(1), 161–208.
[5] Mittal, K. L. Ed. (1984). Synthesis, Characterization and Applications, Plenum
Press: New York, U.S.A., Vol. 1.
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Persoons, A. (2000). Polymer, 41, 6049–6054.
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