Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films
The derivatives of phenylazobenzoic, phenylazosalicylic acids and azobenzeneazonaphthalene were synthesized and employed to prepare polarizing films based on polyvinyl alcohol (PVA). The single-piece transmittance (T0), polarizing efficiency (PE), dichroic ratio (Rd) of films and order parameter...
Збережено в:
| Дата: | 2013 |
|---|---|
| Автори: | , , , , , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2013
|
| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/117697 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films / .N. Filippovich, N.G. Ariko, H.A. Almodarresiyeh, S.N. Shahab, P.M. Malashko, V.E. Agabekov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2013. — Т. 16, № 2. — С. 220-23. — Бібліогр.: 7 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-117697 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-1176972017-05-27T03:03:40Z Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films Filippovich, L.N. Ariko, N.G. Almodarresiyeh, H.A. Shahab, S.N. Malashko, P.M. Agabekov, V.E. The derivatives of phenylazobenzoic, phenylazosalicylic acids and azobenzeneazonaphthalene were synthesized and employed to prepare polarizing films based on polyvinyl alcohol (PVA). The single-piece transmittance (T0), polarizing efficiency (PE), dichroic ratio (Rd) of films and order parameter of dyes (Sdye) were calculated. It was found that parameters Rd and Sdye increased as electron-donating of substituents in molecules of phenylazobenzoic and phenylazosalicylic acids derivatives was grown, and the polarizing efficiency of film increased with increasing the order parameter of dye. Development of PVA films dyed with the derivatives of phenylazosalicylic acid and azobenzeneazonaphthalene allowed to obtain polarizers for near UV and visible range of spectrum, respectively. It was also developed a broadband polarizer for 300-610 nm. 2013 Article Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films / .N. Filippovich, N.G. Ariko, H.A. Almodarresiyeh, S.N. Shahab, P.M. Malashko, V.E. Agabekov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2013. — Т. 16, № 2. — С. 220-23. — Бібліогр.: 7 назв. — англ. 1560-8034 PACS 42.79.Ci http://dspace.nbuv.gov.ua/handle/123456789/117697 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| description |
The derivatives of phenylazobenzoic, phenylazosalicylic acids and
azobenzeneazonaphthalene were synthesized and employed to prepare polarizing films
based on polyvinyl alcohol (PVA). The single-piece transmittance (T0), polarizing
efficiency (PE), dichroic ratio (Rd) of films and order parameter of dyes (Sdye) were
calculated. It was found that parameters Rd and Sdye increased as electron-donating of
substituents in molecules of phenylazobenzoic and phenylazosalicylic acids derivatives
was grown, and the polarizing efficiency of film increased with increasing the order
parameter of dye. Development of PVA films dyed with the derivatives of
phenylazosalicylic acid and azobenzeneazonaphthalene allowed to obtain polarizers for
near UV and visible range of spectrum, respectively. It was also developed a broadband
polarizer for 300-610 nm. |
| format |
Article |
| author |
Filippovich, L.N. Ariko, N.G. Almodarresiyeh, H.A. Shahab, S.N. Malashko, P.M. Agabekov, V.E. |
| spellingShingle |
Filippovich, L.N. Ariko, N.G. Almodarresiyeh, H.A. Shahab, S.N. Malashko, P.M. Agabekov, V.E. Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Filippovich, L.N. Ariko, N.G. Almodarresiyeh, H.A. Shahab, S.N. Malashko, P.M. Agabekov, V.E. |
| author_sort |
Filippovich, L.N. |
| title |
Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films |
| title_short |
Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films |
| title_full |
Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films |
| title_fullStr |
Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films |
| title_full_unstemmed |
Structure effect and orientation distribution of azo dyes on optical anisotropy of dyed PVA-films |
| title_sort |
structure effect and orientation distribution of azo dyes on optical anisotropy of dyed pva-films |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2013 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/117697 |
| citation_txt |
Structure effect and orientation distribution of azo dyes
on optical anisotropy of dyed PVA-films / .N. Filippovich, N.G. Ariko, H.A. Almodarresiyeh, S.N. Shahab, P.M. Malashko, V.E. Agabekov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2013. — Т. 16, № 2. — С. 220-23. — Бібліогр.: 7 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT filippovichln structureeffectandorientationdistributionofazodyesonopticalanisotropyofdyedpvafilms AT arikong structureeffectandorientationdistributionofazodyesonopticalanisotropyofdyedpvafilms AT almodarresiyehha structureeffectandorientationdistributionofazodyesonopticalanisotropyofdyedpvafilms AT shahabsn structureeffectandorientationdistributionofazodyesonopticalanisotropyofdyedpvafilms AT malashkopm structureeffectandorientationdistributionofazodyesonopticalanisotropyofdyedpvafilms AT agabekovve structureeffectandorientationdistributionofazodyesonopticalanisotropyofdyedpvafilms |
| first_indexed |
2025-07-08T12:39:08Z |
| last_indexed |
2025-07-08T12:39:08Z |
| _version_ |
1837082454338306048 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 220-223.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
220
PACS 42.79.Ci
Structure effect and orientation distribution of azo dyes
on optical anisotropy of dyed PVA-films
L.N. Filippovich1, N.G. Ariko1, H.A. Almodarresiyeh1, S.N. Shahab1, P.M. Malashko2, V.E. Agabekov2
1Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus
13, Surganova str., 220072 Minsk, Belarus;
2Institute of New Materials Chemistry, National Academy of Sciences of Belarus
36, F. Skaryny str., 220141 Minsk, Belarus; e-mail: luda1977@list.ru
Abstract. The derivatives of phenylazobenzoic, phenylazosalicylic acids and
azobenzeneazonaphthalene were synthesized and employed to prepare polarizing films
based on polyvinyl alcohol (PVA). The single-piece transmittance (T0), polarizing
efficiency (PE), dichroic ratio (Rd) of films and order parameter of dyes (Sdye) were
calculated. It was found that parameters Rd and Sdye increased as electron-donating of
substituents in molecules of phenylazobenzoic and phenylazosalicylic acids derivatives
was grown, and the polarizing efficiency of film increased with increasing the order
parameter of dye. Development of PVA films dyed with the derivatives of
phenylazosalicylic acid and azobenzeneazonaphthalene allowed to obtain polarizers for
near UV and visible range of spectrum, respectively. It was also developed a broadband
polarizer for 300-610 nm.
Keywords: dichroic polarizers, polyvinyl alcohol, mono- and disazodyes, spectral-
polarizing properties.
Manuscript received 21.12.12; revised version received 12.02.13; accepted for
publication 19.03.13; published online 25.06.13.
1. Introduction
Dichroic film polarizers are polymer uniaxially oriented
films colored with molecular iodine or organic dyes.
Polarizers based on polyvinyl alcohol (PVA) have the
most practical application. The study of spectral
properties of PVA films colored by different classes of
dyes showed that the azocompounds can get film
material with a high polarizing ability. However, the
optical properties of these polarizers are dependent on
many factors: the structure and the orientation
distribution of the dye molecules in the polymer matrix,
phase state and supramolecular structure of PVA,
intermolecular interactions between dye molecules and
macromolecules of the polymer [1 – 3].
In this work, the derivatives of phenylazobenzoic,
phenylazosalicylic acids and azobenzeneazonaphthalene
were synthesized, and then they were used for dyeing the
PVA-films polarizing in near UV and visible regions of
the spectrum. The purpose of this study is to determine the
influence of the molecular structure (type and location of
auxochrome group) of the synthesized compounds and the
orientation distribution of dyes molecules in the polymer
matrix on dichroism of PVA-films.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 220-223.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
221
2. Experiment
Disazodyes:
N=N N=NNaO3S
NH2
OH
NaO3S
OCH3
М1
N=N N=N
SO3Na
NH2
HO
М2
N=N N=N
NH2
OH
NaO3S
М3
N=N N=N
OCH3
NaO3S SO3Na
NH2 OH
IV
N=NN=N
NaO3S SO3Na
NH2 OH
V
N=N
NaO3S
SO3Na
NH2
N
N
VI
and monoazodyes (Table 2) of the general formula:
N=N R1
R2
R3
were synthesized in the form of free acids or their
sodium salts by the diazotization of aromatic amines or
diamines followed by azocoupling with salicylic,
aminonaftolsulfo and acetoacetic acid in acidic or
alkaline medium [4]. Preparation of polarizing films is
described in [5].
Absorption and transmission spectra of films were
measured using a UV-NIR Spectrometer HR4000CG
(Ocean Optics, USA) equipped with wire-grid polarizer
UBB01A (Moxtek, USA).
Optical properties of the polarizers were expressed
in terms of such optical characteristics as the single-
piece transmittance (T0), polarizing efficiency (PE) and
dichroic ratio (Rd) of dyed PVA-films. The order
parameter (Sdye) characterized the degree of aligning dye
molecules toward the orientation film axis. These
parameters were calculated by means of the
equations [6]:
Т0 = (Т|| + Т)/2, PE = {(Т Т||) / (Т|| + Т)}∙100%,
Rd = D|| / D, Sdye = (Rd 1)/(Rd + 2),
where D||, D absorption and Т||, Т film
transmittance of linearly polarized light in parallel (||)
and perpendicular () orientation of the electric vector
of linearly polarized light towards the orientation axis of
the film.
3. Results and discussion
Investigated PVA-films colored with mono- and
disazodyes have a positive dichroism, which proves that
the long-wave absorption dye oscillator is directed along
its main molecular axis. The latter, in its turn, is oriented
in the direction of the film orientation axis. Polarization
efficiency of a film is determined primarily by the
structure of dye molecules embedded in polymer. So, the
samples obtained under identical conditions and
polarized in the visible range of spectrum have the
values of PE from 33 up to 98% (Table 1). Besides, the
similar change of the order parameter Sdye can be seen.
Ab initio SCF MO LCAO RHF/MINI (3d) method
was used in order to model the spatial structure of the
dyes. It was found that the highest value of PE is
inherent to the films colored with molecules that have a
flat “extension” frame of two benzene and single
naphthalene rings without volume substitutes causing
steric hindrance for the alignment of dye molecules
along the polymer chains and towards the drawing
direction (compounds M1, M2 and M3).
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 220-223.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
222
Table 1. Sdye and PE for films dyed with disazodyes. The dye concentration is 0.2-0.4 mas.%. The film thickness is 60 μm.
Dye max, nm D D Rd Sdye PE, %
М1 595 1.52 0.15 10.1 0.75 92
М2 585 2.22 0.50 4.4 0.53 96
М3 580 2.19 0.26 8.4 0.71 98
IV 495 1.57 0.40 3.9 0.49 87
V 570 0.80 0.46 1.7 0.19 61
VI 507 0.62 0.33 1.9 0.23 33
Table 2. Order parameter and spectral-polarization characteristics of the films dyed by monoazodyes. The dye
concentration is 0.2 to 0.3 mas.%. The film thickness is close to 50…60 µm.
Т Т
Substituent Cipher
of dye
max,
nm %
D D Т0,
%
Rd Sdye PE,
%
R1= COONa, R2 = Н,
R3= COONa VII 351 75.6 2.8 0.122 1.553 39.2 12.7 0.80 93
R1= COOH, R2 = Н,
R3= COOH VIII 351 91.4 11.5 0.039 0.939 51.4 24.0 0.89 78
R1= OH, R2 = COONa,
R3= CH3-C(O) IX 381 43.0 1.4 0.367 1.854 22.2 5.1 0.58 94
R1= OH, R2 = COOH,
R3= CH3-C(O) X 381 42.5 0.5 0.372 2.301 21.5 6.2 0.63 98
R1= OH, R2 = COONa,
R3= CH3-C(O)-NH XI 376 28.6 0.01 0.544 4.000 14.3 7.4 0.68 99
R1= OH, R2 = COONa,
R3= NaOOC XII 380 78.1 4.2 0.107 1.377 41.1 12.9 0.80 90
R1= OH, R2 = COONa,
R3= NH2 XIII 399 64.7 0.5 0.189 2.301 32.6 12.2 0.79 99
R1= OH, R2 = COONa,
R3= CH3O-C6H4-C2H2-C(O) XIV 386 51.4 1.3 0.289 1.886 26.4 6.5 0.65 95
R1= OH, R2 = COOH,
R3= CH3O-C6H4-C2H2-C(O) XV 382 41.7 0.6 0.380 2.222 21.2 5.8 0.61 97
Sulfo-groups do not violate flatness of molecules
M1 and M3. Violation of coplanarity of the dye
molecules IV and V reduces the intensity of the long-
wave absorption bands and decrease values of Sdye and
PE. Molecules of dye VI, the length of which is
comparable with their width, are oriented in polymer
matrix with different angles of deviation of its main
absorption axis along the drawing axis, which is the
reason for the low polarizing ability of dyed PVA-film.
Monoazoderivatives of benzoic and salicylic acid
are effective dichroic components of films polarizing in
the near UV range of the spectrum (Table 2).
The nature of substituents in the dye molecule
affects not only on the position and intensity of the long-
wave absorption band of the film, but also on its
dichroism. “Delete” from the conjugation one of the
NaO(O)C-group in the dye VII and the introduction of
the e-supplying group OH on its place:
N=N COONaNaOOC
VII
N=N OH
COONa
NaOOC
XII
does not practically change the value of the order
parameter Rd, but replacing the second NaO(O)C-group
on e-withdrawing substituent R = СН3С(О) – (IX),
CH3C(O)NH- (XI), CH3(O)Ar-CH = CH – C(O) – (XIV)
N=NR OH
COONa
reduces Rd from 12.2…12.7 to ~5-7. With the e-
supplying group NH2:
N=N OHNH2
COONa
XIII
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 220-223.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
223
Rd returned to 12.2. In general, with increase of electron-
donating of substituents the value of dichroic ratio
increases:
R: NH2- > CH3C(O)NH- > СН3(O)Ar-CH=CH-C(O)- > СН3С(О)
Rd: 12.2 > 7.4 > 6.5 > 5.1
The value of Sdye (Table 2) also depends on the
structure of dye and for the compounds VII-XV is:
R: NaO(O)C-NH2-CH3C(O)NH-СН3(O)Ar-CH=CH-C(O)- СН3С(О)
Scr: 0.80 0.79 0.68 0.65 0.63
Since the orientation of the dye strongly depends
on the spatial structure of its molecules [7], introduction
of larger volume substituents -NHOCCH3 ,
-OC-CHCH-ArOCH3 and CH3C(O) compared
to groups NaO(O)C- and NH2- reduces Sdye.
The order parameter Sdye decreases with increasing
the dye concentration (C) in the film. For example, the
increase of C for dye IX from 0.15 up to 0.30 mas.%
reduces the value of Sdye from 0.63 to 0.58, and in the
case of dye XIII the growth of C from 0.2 up to
0.4 mas.% causes the decrease in Sdye from 0.88 down to
0.71. This dependence CSdye was predicted using the
mathematical model worked out to describe the spectral-
polarizing properties of dyed PVA films and was
experimentally proved with film samples containing azo
dye “direct blue”[6].
The orientation degree of the dye molecules
increases in films with a quasi-crystalline structure of
PVA that is formed after the heat treatment of the PVA-
film and the processing by “cross-linking” agent (boric
acid) [5]. This structure is characterized by a highly
ordered polymer chains with respect to the drawing axis
of the film, and as a result increase the degree of
orientation of the dye molecules in the polymer matrix.
For example, the parameter Sdye of the dye M1 in films
untreated and treated with boric acid is equal to 0.63 and
0.78, respectively [5].
Studying the optical properties of PVA-films dyed
by (M3H) obtained by treatment of dye M3 with
hydrochloric acid, we found that M3H is an effective
dichroic component of films polarizing in near UV and
visible ranges of spectrum (Fig. 1). The polarization
efficiency of this film is 92 to 99% (300…400 nm) and
96 to 99% (400…610 nm).
Fig. 1. Transmission spectra and polarizing ability of PVA-
film dyed by M3H. 1 – Т||, 2 – Т┴, 3 – PE; film thickness is
60 μm; dye concentration is 0.4 mas.%.
4. Conclusion
The structure of molecules of derivatives of
phenylazobenzoic and phenylazosalicylic acids as well
as azobenzeneazonaphtalene influences on optical
properties of polarizing PVA films and orientation
alignment of azodyes in polymeric matrix. With rising
electron-donating of the substituents conjugated with the
chain of double bonds in derivatives of
phenylazobenzoic and phenylazosalicylic acids, the
dichroic ratio of film and the order parameter of dye (a
degree of dye orientation in polymer matrix) increase.
The polarizing ability of films grows with rising the
order parameter of dye, the value of which depends on
the concentration of dye and the supramolecular
structure of polymer matrix. From PVA dyed by
synthesized mono- and disazodyes we obtained the
polarizers for UV and visible ranges of the spectrum as
well as the broadband polarizer for the range
300…610 nm.
Acknowledgement
The authors are grateful to Dr. V. Zelenkovskii for
assistance in the work to optimize the geometry of dye
structure.
References
1. J.B. Cnang, J.H. Hwang, S. Jong, The effect of dye
structure on the dyeing and optical properties of
dichroic dyes for polarizing film // Dyes and
pigmentes, 88, р. 366-371 (2011).
2. D.H. Song, H.Y. Yoo, J.P. Kim, Synthesis of
stilbene-based azo dyes and application for dichroic
materials in poly(vinyl alcohol) polarizing films //
Dyes and pigments, 75, р. 727-731 (2007).
3. A. Altomare, F. Ciardelli, M. Marchini, R. Solaro,
Polymer dispersions of model azobenzele dyes //
Polymer, 46, р. 2086-2096 (2005).
4. B.А. Poraj-Koshitz, Аzodyes. Chemistry,
Leningrad, 1972 (in Russian).
5. V.Е. Аgabekov, N.G. Аriko, S.N. Shahab, L.N.
Filippovich, P.M. Malashko, The influence of dyes
nature and structure of polymer on optical and
thermal properties of film polarizers // Dokl.
BGYIR, 5, p. 109-118 (2008).
6. S.E. Han, I.S. Hwang, Modeling of the optical
anisotropy of a dye polarizer // J. Polymer Sci. Part
B. Polymer Physics, 40, р. 1363-1370 (2002).
7. B.T. Kobayashi, Y. Tanizaki, N. Ando, Absorption
spectra of dyes. VI. Steric effects in conjugated
systems of benzidine disazo dyes and their copper
derivatives // Bull. Chem. Soc. Japan, 33, р. 913-
917 (1960).
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 220-223.
PACS 42.79.Ci
Structure effect and orientation distribution of azo dyes
on optical anisotropy of dyed PVA-films
L.N. Filippovich1, N.G. Ariko1, H.A. Almodarresiyeh1, S.N. Shahab1, P.M. Malashko2, V.E. Agabekov2
1Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus
13, Surganova str., 220072 Minsk, Belarus;
2Institute of New Materials Chemistry, National Academy of Sciences of Belarus
36, F. Skaryny str., 220141 Minsk, Belarus; e-mail: luda1977@list.ru
Abstract. The derivatives of phenylazobenzoic, phenylazosalicylic acids and azobenzeneazonaphthalene were synthesized and employed to prepare polarizing films based on polyvinyl alcohol (PVA). The single-piece transmittance (T0), polarizing efficiency (PE), dichroic ratio (Rd) of films and order parameter of dyes (Sdye) were calculated. It was found that parameters Rd and Sdye increased as electron-donating of substituents in molecules of phenylazobenzoic and phenylazosalicylic acids derivatives was grown, and the polarizing efficiency of film increased with increasing the order parameter of dye. Development of PVA films dyed with the derivatives of phenylazosalicylic acid and azobenzeneazonaphthalene allowed to obtain polarizers for near UV and visible range of spectrum, respectively. It was also developed a broadband polarizer for 300-610 nm.
Keywords: dichroic polarizers, polyvinyl alcohol, mono- and disazodyes, spectral-polarizing properties.
Manuscript received 21.12.12; revised version received 12.02.13; accepted for publication 19.03.13; published online 25.06.13.
1. Introduction
Dichroic film polarizers are polymer uniaxially oriented films colored with molecular iodine or organic dyes. Polarizers based on polyvinyl alcohol (PVA) have the most practical application. The study of spectral properties of PVA films colored by different classes of dyes showed that the azocompounds can get film material with a high polarizing ability. However, the optical properties of these polarizers are dependent on many factors: the structure and the orientation distribution of the dye molecules in the polymer matrix, phase state and supramolecular structure of PVA, intermolecular interactions between dye molecules and macromolecules of the polymer [1 – 3].
In this work, the derivatives of phenylazobenzoic, phenylazosalicylic acids and azobenzeneazonaphthalene were synthesized, and then they were used for dyeing the PVA-films polarizing in near UV and visible regions of the spectrum. The purpose of this study is to determine the influence of the molecular structure (type and location of auxochrome group) of the synthesized compounds and the orientation distribution of dyes molecules in the polymer matrix on dichroism of PVA-films.
2. Experiment
Disazodyes:N
=N
N
=N
N
a
O
3
S
N
H
2
O
H
N
a
O
3
S
O
C
H
3
N=N
N=N
NaO
3
S
NH
2
OH
NaO
3
S
OCH
3
М1
N
=N
N
=N
S
O
3
N
a
N
H
2
H
O
N=N
N=N
SO
3
Na
NH
2
HO
М2
N
=N
N
=N
N
H
2
O
H
N
a
O
3
S
N=N
N=N
NH
2
OH
NaO
3
S
М3
N
=N
N
=N
O
C
H
3
N
a
O
3
S
S
O
3
N
a
N
H
2
O
H
N=N
N=N
OCH
3
NaO
3
S
SO
3
Na
NH
2
OH
IV
N
=N
N
=N
N
a
O
3
S
S
O
3
N
a
N
H
2
O
H
N=N
N=N
NaO
3
S
SO
3
Na
NH
2
OH
V
N
=N
N
a
O
3
S
S
O
3
N
a
N
H
2
N
N
N=N
NaO
3
S
SO
3
Na
NH
2
N
N
VI
and monoazodyes (Table 2) of the general formula:
N
=
N
R
1
R
2
R
3
N=N
R
1
R
2
R
3
were synthesized in the form of free acids or their sodium salts by the diazotization of aromatic amines or diamines followed by azocoupling with salicylic, aminonaftolsulfo and acetoacetic acid in acidic or alkaline medium [4]. Preparation of polarizing films is described in [5].
Absorption and transmission spectra of films were measured using a UV-NIR Spectrometer HR4000CG (Ocean Optics, USA) equipped with wire-grid polarizer UBB01A (Moxtek, USA).
Optical properties of the polarizers were expressed in terms of such optical characteristics as the single-piece transmittance (T0), polarizing efficiency (PE) and dichroic ratio (Rd) of dyed PVA-films. The order parameter (Sdye) characterized the degree of aligning dye molecules toward the orientation film axis. These parameters were calculated by means of the equations [6]:
Т0 = (Т|| + Т()/2, PE = {(Т( ( Т||) / (Т|| + Т()}∙100%,
Rd = D|| / D(, Sdye = (Rd ( 1)/(Rd + 2),
where D||, D( ( absorption and Т||, Т( ( film transmittance of linearly polarized light in parallel (||) and perpendicular (() orientation of the electric vector of linearly polarized light towards the orientation axis of the film.
3. Results and discussion
Investigated PVA-films colored with mono- and disazodyes have a positive dichroism, which proves that the long-wave absorption dye oscillator is directed along its main molecular axis. The latter, in its turn, is oriented in the direction of the film orientation axis. Polarization efficiency of a film is determined primarily by the structure of dye molecules embedded in polymer. So, the samples obtained under identical conditions and polarized in the visible range of spectrum have the values of PE from 33 up to 98% (Table 1). Besides, the similar change of the order parameter Sdye can be seen.
Ab initio SCF MO LCAO RHF/MINI (3d) method was used in order to model the spatial structure of the dyes. It was found that the highest value of PE is inherent to the films colored with molecules that have a flat “extension” frame of two benzene and single naphthalene rings without volume substitutes causing steric hindrance for the alignment of dye molecules along the polymer chains and towards the drawing direction (compounds M1, M2 and M3).
Sulfo-groups do not violate flatness of molecules M1 and M3. Violation of coplanarity of the dye molecules IV and V reduces the intensity of the long-wave absorption bands and decrease values of Sdye and PE. Molecules of dye VI, the length of which is comparable with their width, are oriented in polymer matrix with different angles of deviation of its main absorption axis along the drawing axis, which is the reason for the low polarizing ability of dyed PVA-film.
Monoazoderivatives of benzoic and salicylic acid are effective dichroic components of films polarizing in the near UV range of the spectrum (Table 2).
The nature of substituents in the dye molecule affects not only on the position and intensity of the long-wave absorption band of the film, but also on its dichroism. “Delete” from the conjugation one of the NaO(O)C-group in the dye VII and the introduction of the e-supplying group OH on its place:
N
=
N
C
O
O
N
a
N
a
O
O
C
N=N
COONa
NaOOC
VII
N
=
N
O
H
C
O
O
N
a
N
a
O
O
C
N=N
OH
COONa
NaOOC
XII
does not practically change the value of the order parameter Rd, but replacing the second NaO(O)C-group on e-withdrawing substituent R = СН3С(О) – (IX), CH3C(O)NH- (XI), CH3(O)Ar-CH = CH – C(O) – (XIV)
N
=
N
R
O
H
C
O
O
N
a
N=N
R
OH
COONa
reduces Rd from 12.2…12.7 to ~5-7. With the e-supplying group NH2:
N
=
N
O
H
N
H
2
C
O
O
N
a
N=N
OH
NH
2
COONa
XIII
Rd returned to 12.2. In general, with increase of electron-donating of substituents the value of dichroic ratio increases:
R: NH2- > CH3C(O)NH- > СН3(O)Ar-CH=CH-C(O)- > СН3С(О)
Rd: 12.2 > 7.4 > 6.5 > 5.1
The value of Sdye (Table 2) also depends on the structure of dye and for the compounds VII-XV is:
R: NaO(O)C-NH2-CH3C(O)NH-СН3(O)Ar-CH=CH-C(O)- СН3С(О)
Scr: 0.80 0.79 0.68 0.65 0.63
Since the orientation of the dye strongly depends on the spatial structure of its molecules [7], introduction of larger volume substituents
(
)
-
NH
O
C
CH
3
,
(
)
(
)
-
O
C
-
CH
CH
-
Ar
O
CH
3
=
and CH3C(O) compared to groups NaO(O)C- and NH2- reduces Sdye.
The order parameter Sdye decreases with increasing the dye concentration (C) in the film. For example, the increase of C for dye IX from 0.15 up to 0.30 mas.% reduces the value of Sdye from 0.63 to 0.58, and in the case of dye XIII the growth of C from 0.2 up to 0.4 mas.% causes the decrease in Sdye from 0.88 down to 0.71. This dependence
C
S
dye
-
was predicted using the mathematical model worked out to describe the spectral-polarizing properties of dyed PVA films and was experimentally proved with film samples containing azo dye “direct blue”[6].
The orientation degree of the dye molecules increases in films with a quasi-crystalline structure of PVA that is formed after the heat treatment of the PVA-film and the processing by “cross-linking” agent (boric acid) [5]. This structure is characterized by a highly ordered polymer chains with respect to the drawing axis of the film, and as a result increase the degree of orientation of the dye molecules in the polymer matrix. For example, the parameter Sdye of the dye M1 in films untreated and treated with boric acid is equal to 0.63 and 0.78, respectively [5].
Studying the optical properties of PVA-films dyed by (M3H) obtained by treatment of dye M3 with hydrochloric acid, we found that M3H is an effective dichroic component of films polarizing in near UV and visible ranges of spectrum (Fig. 1). The polarization efficiency of this film is 92 to 99% (300…400 nm) and 96 to 99% (400…610 nm).
Fig. 1. Transmission spectra and polarizing ability of PVA-film dyed by M3H. 1 – Т||, 2 – Т┴, 3 – PE; film thickness is 60 μm; dye concentration is 0.4 mas.%.
4. Conclusion
The structure of molecules of derivatives of phenylazobenzoic and phenylazosalicylic acids as well as azobenzeneazonaphtalene influences on optical properties of polarizing PVA films and orientation alignment of azodyes in polymeric matrix. With rising electron-donating of the substituents conjugated with the chain of double bonds in derivatives of phenylazobenzoic and phenylazosalicylic acids, the dichroic ratio of film and the order parameter of dye (a degree of dye orientation in polymer matrix) increase. The polarizing ability of films grows with rising the order parameter of dye, the value of which depends on the concentration of dye and the supramolecular structure of polymer matrix. From PVA dyed by synthesized mono- and disazodyes we obtained the polarizers for UV and visible ranges of the spectrum as well as the broadband polarizer for the range 300…610 nm.
Acknowledgement
The authors are grateful to Dr. V. Zelenkovskii for assistance in the work to optimize the geometry of dye structure.
References
1.
J.B. Cnang, J.H. Hwang, S. Jong, The effect of dye structure on the dyeing and optical properties of dichroic dyes for polarizing film // Dyes and pigmentes, 88, р. 366-371 (2011).
2.
D.H. Song, H.Y. Yoo, J.P. Kim, Synthesis of stilbene-based azo dyes and application for dichroic materials in poly(vinyl alcohol) polarizing films // Dyes and pigments, 75, р. 727-731 (2007).
3.
A. Altomare, F. Ciardelli, M. Marchini, R. Solaro, Polymer dispersions of model azobenzele dyes // Polymer, 46, р. 2086-2096 (2005).
4.
B.А. Poraj-Koshitz, Аzodyes. Chemistry, Leningrad, 1972 (in Russian).
5.
V.Е. Аgabekov, N.G. Аriko, S.N. Shahab, L.N. Filippovich, P.M. Malashko, The influence of dyes nature and structure of polymer on optical and thermal properties of film polarizers // Dokl. BGYIR, 5, p. 109-118 (2008).
6.
S.E. Han, I.S. Hwang, Modeling of the optical anisotropy of a dye polarizer // J. Polymer Sci. Part B. Polymer Physics, 40, р. 1363-1370 (2002).
7.
B.T. Kobayashi, Y. Tanizaki, N. Ando, Absorption spectra of dyes. VI. Steric effects in conjugated systems of benzidine disazo dyes and their copper derivatives // Bull. Chem. Soc. Japan, 33, р. 913-917 (1960).
Table 1. Sdye and PE for films dyed with disazodyes. The dye concentration is 0.2-0.4 mas.%. The film thickness is 60 μm.
Dye�
(max, nm�
D((�
D(�
Rd�
Sdye�
PE, %�
�
М1�
595�
1.52�
0.15�
10.1�
0.75�
92�
�
М2�
585�
2.22�
0.50�
4.4�
0.53�
96�
�
М3�
580�
2.19�
0.26�
8.4�
0.71�
98�
�
IV�
495�
1.57�
0.40�
3.9�
0.49�
87�
�
V�
570�
0.80�
0.46�
1.7�
0.19�
61�
�
VI�
507�
0.62�
0.33�
1.9�
0.23�
33�
�
Table 2. Order parameter and spectral-polarization characteristics of the films dyed by monoazodyes. The dye concentration is 0.2 to 0.3 mas.%. The film thickness is close to 50…60 µm.
Substituent�
Cipher of dye�
(max,
nm�
Т(�
Т((�
D( �
D((�
Т0,
%�
Rd �
Sdye�
PE,
%�
�
�
�
�
%�
�
�
�
�
�
�
�
R1= COONa, R2 = Н,
R3= COONa�
VII�
351�
75.6�
2.8�
0.122�
1.553�
39.2�
12.7�
0.80�
93�
�
R1= COOH, R2 = Н,
R3= COOH�
VIII�
351�
91.4�
11.5�
0.039�
0.939�
51.4�
24.0�
0.89�
78�
�
R1= OH, R2 = COONa,
R3= CH3-C(O)�
IX�
381�
43.0�
1.4�
0.367�
1.854�
22.2�
5.1�
0.58�
94�
�
R1= OH, R2 = COOH,
R3= CH3-C(O)�
X�
381�
42.5�
0.5�
0.372�
2.301�
21.5�
6.2�
0.63�
98�
�
R1= OH, R2 = COONa,
R3= CH3-C(O)-NH�
XI�
376�
28.6�
0.01�
0.544�
4.000�
14.3�
7.4�
0.68�
99�
�
R1= OH, R2 = COONa,
R3= NaOOC�
XII�
380�
78.1�
4.2�
0.107�
1.377�
41.1�
12.9�
0.80�
90�
�
R1= OH, R2 = COONa,
R3= NH2�
XIII�
399�
64.7�
0.5�
0.189�
2.301�
32.6�
12.2�
0.79�
99�
�
R1= OH, R2 = COONa, R3= CH3O-C6H4-C2H2-C(O)�
XIV�
386�
51.4�
1.3�
0.289�
1.886�
26.4�
6.5�
0.65�
95�
�
R1= OH, R2 = COOH,
R3= CH3O-C6H4-C2H2-C(O)�
XV�
382�
41.7�
0.6�
0.380�
2.222�
21.2�
5.8�
0.61�
97�
�
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
220
_1433772489.unknown
_1442414437.unknown
_1433772487.unknown
|