Crown-ether and azobenzene-containing liquid crystalline polymers: An influence of macromolecular architecture on optical properties and photo-orientation processes

Article abstract of DOI:10.1002/pola.24472

A series of novel crown ether-containing photochromic comb-shaped liquid crystalline polyacrylates with different macromolecular structure of side groups were synthesized and investigated. Phase behavior, optical and photo-optical properties of thin spin-coated films of these polymers were studied. A special attention was paid to a comparative study of the photo-orientation phenomena occurring in the polymer films under a polarized light action. It was shown that complex formation with the potassium ions results in the decrease in degree of the photoinduced order that can be used for the creation of new materials for sensor devices.

Full text of DOI:10.1002/pola.24472

Crown-Ether and Azobenzene-Containing Liquid Crystalline Polymers:
An Influence of Macromolecular Architecture on Optical Properties and
Photo-Orientation Processes
ALEXANDER RYABCHUN, ALEXEY BOBROVSKY, ALEXEY MEDVEDEV, VALERY SHIBAEV
Faculty of Chemistry, Moscow State University, Lenin Hills, Moscow 119991 Russia
Received 30 August 2010; accepted 27 October 2010
DOI: 10.1002/pola.24472
Published online 8 December 2010 in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: A series of novel crown ether-containing photochro-
mic comb-shaped liquid crystalline polyacrylates with different
macromolecular structure of side groups were synthesized and
investigated. Phase behavior, optical and photo-optical proper-
ties of thin spin-coated films of these polymers were studied.
A special attention was paid to a comparative study of the
photo-orientation phenomena occurring in the polymer films
under a polarized light action. It was shown that complex
formation with the potassium ions results in the decrease
in degree of the photoinduced order that can be used for the
C
V
creation of new materials for sensor devices.
2010 Wiley
Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 625–633,
2011
KEYWORDS: azo polymers; azobenzene groups; complexation;
crown ether; liquid-crystalline polymers (LCP); metal-polymer
complexes; photochemistry; photochromism; photo-orientation
INTRODUCTION Starting from the discovery of crown ethers
in 1960s and until now an active development of materials
having features of these compounds takes place. Today
crown ethers have found applications for metal ion concen-
trations, separation and purification, for isotope separations,
as catalysts in reactions with participation of anions, for ion-
selective sensors and membrane creation.1–3 Sensor systems’
construction of crown ether compounds conjugated with
chromophores4 and fluorophores5 were described recently.
For such substances, changes in absorbance or fluorescence
spectra are observed under complexation. Up to now a large
number of low molar mass crown ether-containing substan-
ces capable of liquid crystalline (LC) phase formation have
been synthesized. Formation of complexes may lead to the
appearance or disruption of supramolecular structures, such
as columnar phases.6,7 Nevertheless, only a few examples of
LC polymers containing crown ether fragments are described
in the literature. Mainly these are polymers having mesogens
and crown ether groups incorporated in polymer back-
bone,8,9 and side-chain homopolymers of acrylic or siloxane
types.10,11 Such polymers combining mesomorphic properties
with metal complexation can be considered as ‘‘smart’’ mate-
rials. There are even fewer examples of photochromic LC
systems based on crown ethers, although properties of
amorphous photochromic derivatives, such as spiropyrans,
triphenylmethanes, diarylethenes, and azobenzene having
crown ether moieties are described quite well.4,12–14 For
example, a series of photochromic azobenzene–crown-con-
taining compounds forming crystalline and nematic phases
were presented.14 It was found that UV-irradiation of these
compound’s films leads to an increase of ionic conductivity,
but irradiation with the visible light has restored the initial
level of conductivity. Recently, we have elaborated and
described synthetic approaches for the synthesis of wide
range of photochromic crown ether-containing LC homopoly-
mers and copolymers based on azobenzenes.15,16 It was
shown that complexation of these compounds with metal
ions results in a decrease of clearing temperature, and in
some cases, formation of complexes leads to a transition into
the amorphous state. In these papers, the kinetic features of
photoisomerization of azobenzene moieties were studied in
detail.
In this article, we have continued our work launched
before15,16 and have performed synthesis of a series of novel
photochromic crown ether-containing polymers with differ-
ent macromolecular structures. One of the main goals of this
work is an investigation of a relation between molecular
architecture of the synthesized polymers and photo-optical
properties and phase behavior of these polymer materials.
We have synthesized three types of polymers with com-
pletely different position of the crown ether fragment with
Additional Supporting Information may be found in the online version of this article. Correspondence to: A. Bobrovsky (E-mail: bbrvsky@yahoo.
com)
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Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 49, 625–633 (2011) 2010 Wiley Periodicals, Inc.
CROWN ETHER- AND AZOBENZENE-CONTAINING LCP, RYABCHUN ET AL.
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
FIGURE 1 Schematic representa-
tion of photochromic crown
ether-containing LC polymers.
respect to the azobenzene photochromic groups (Fig. 1). All
synthesized polymers combine an ability of mesogenic
groups to self-assemble (i.e., LC phase formation), an ability
of photochromic groups to undergo an isomerization under
the light irradiation changing their optical properties, and an
ability of crown ether groups for complex formation.
tion of azobenzene groups in side-chain LC polymers allows
one to obtain light-controllable polymer films and coatings,
which can be used for optical data recording due to the pho-
toinduced E–Z isomerization followed by co-operative photo-
orientation of all mesogenic side groups under the polarized
light action.17
Chemical structures of synthesized polymers are presented
below:
The crown ether fragment was selected as an ionophoric
group because of several reasons. First of all, the crown
ether-containing side group has a capability to form co-ordi-
nation bonds with metal ions that opens the interesting pos-
sibilities for obtaining metal-containing LC polymers. Sec-
ondly,
a complexation can influence the photo-optical
properties of multifunctional materials. A combination of
these three functions in one and the same macromolecule
allows one to obtain a novel type of photoswitchable mate-
rial sensitive to the nonpolarized or polarized light and capa-
ble of complexation with metal ions that present a certain in-
terest for a possible application of such systems as sensor
materials.
Thus, the synthesized samples under investigation con-
sisted of two groups of polymers including homopolymers
P1 and P2 as well as ternary copolymers Cop5 and
Cop15 consisting of the individual monomer units contain-
ing mesogenic nonphotochromic phenylmethoxybenzoate
(I), photochromic azobenzene (II), and ionophoric crown
ether groups (III).
Elucidation of the correlation between the molecular archi-
tecture of these polymers and their mesomorphic, optical
and photo-optical properties is the main goal of this work.
Homopolymer P1 contains the crown ether fragment, which
is directly connected with the photochromic group, whereas
in homopolymer P2, the crown ether moieties and photo-
chromes are linked through the short oxymethylene spacers.
Copolymers Cop5 and Cop15 are ternary copolymers con-
taining 5 and 15 mol % of nonphotochromic crown ether-
containing side groups, respectively; photochromic and
mesogenic side groups in copolymers were taken in equal
proportions.
EXPERIMENTAL
Monomers’ Synthesis
Monomer M1 was synthesized for the first time in this work.
Monomers M2–M5 were synthesized using methods
described before (Supporting Information).15,18,19 Table 1
shows the chemical structures of all synthesized monomers
and their melting temperatures.
Azobenzene moieties were used as photochromic fragments
in all synthesized polymers. It is well known that introduc-
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TABLE 1 Chemical Structures and Melting Temperatures of Crown Ether-Containing, Nematogenic and Photochromic Monomers
Chemical Structure
Tm (ꢀC)
Reference
This paper
M1
55
M2
M3
58
52
13
13
M4
M5
82
88
16
17
Synthesis of Monomer M1
aminopyridine. To the solution, 0.35 g (1.7 mmol) of N,N0-
dicyclohexylcarbodiimide cooled by ice with water was
added during 1.5 h. The reaction was completed after mixing
at room temperature for 24 h. The precipitate of bicyclohex-
ylurea was filtered, and THF was evaporated. The product
was purified using column chromatography (silica gel,
eluent—chlorophorm/methanol, 15:1). The yield was 0.46 g
(55% from theory). The oꢀbtained monomer was a dark-or-
ange powder with m.p. 55 C.
1H NMR (400 MHz, CDCl3, TMS, d): 1.26–1.87 (m, 8H, CH2),
3.55–3.85 (m, 12H, CH2O), 3.97 (m, 4H, CH2CH2O), 4.25 (m,
4H, CH2CH2O), 4.05 (t, 2H, CH2O), 4.17 (t, 2H, CH2O), 5.81
(dd, 1H, CH2¼¼CH-trans), 6.4 (dd, 1H, CH2¼¼CH-cis), 6.12 (dd,
1H, CH2¼¼CHA), 6.98 (d, 3H, Ar), 7.33 (d, 2H, Ar), 7.6 (d, 2H,
Ar, ortho to AOOCA), 7.97 (d, 2H, Ar), 8.15 (d, 2H, Ar, ortho
to ACOOA). 13C NMR and MS are presented in Supporting
Information.
Polymers’ Synthesis
Monomer M1 was synthesized using a two-step synthetic
route. In the first step, an azobenzene dye was synthesized
using standard azo-coupling with phenol in alkaline media
(more detailed procedure is presented in Supporting Infor-
mation).20 In the second step, 0.35 g (1.2 mmol) of previ-
ously obtained 4-{[6-(acryloyloxy)hexyl]oxy}benzoic acid
(A6) synthesized according to ref. 21 was mixed with 0.63 g
(1.5 mmol) of azobenzene dye in nonaqueous Tetrahydrofuran
(THF) in the presence of 0.03 g (0.25 mmol) of 4-dimethyl-
Homopolymers and copolymers were synthesized by radical
polymerization of the corresponding monomers in dry ben-
zene. The reaction was performed in the sealed ampoules in
argon atmosphere during 100 h at 60 ꢀC in the presence of
AIBN (1–2% to monomers mass). For the purification from
the low-molar mass admixture, the polymers were washed
with boiling methanol for a long time. Polymers were dried
in vacuum at 100 ꢀC. Molecular masses of the synthesized
polymers were determined by GPC using
a
‘‘Knauer’’
CROWN ETHER- AND AZOBENZENE-CONTAINING LCP, RYABCHUN ET AL.
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
TABLE 2 Yields, Molecular Mass Characteristics, and Phase
Dichroism values D were calculated by the following Equa-
Transition Temperatures of the Synthesized Polymers
tion (1):
Polymer
Yield (%)
Mw (kDa)
Mw/Mn
Phase Transitions
D ¼ ðA ꢂ A Þ=ðA þ A Þ
?
?
jj
jj
P1
28
58
65
53
51
10.3
5.6
7.9
9.8
8.4
1.7
1.5
1.5
1.7
1.6
g 24 N 103 I
g 11 N 74 I
g 24 N 120 I
g 21 N 111 I
g 17 N 63 I
in which A and A are absorbances along and perpendicular
of chromophore orientations, respectively.
k
?
P2
Cop0a
Cop5
Cop15
a
RESULTS AND DISCUSSION
Synthesis and Phase Behavior of Polymers
All synthesized polymers display a nematic LC phase that is
confirmed by the formation of schlieren and marbled tex-
tures and low enthalpies of isotropization (0.7–1.1 J/g).
Double copolymer without crown ether side groups.
chromatograph (UV-detector; columns ‘‘LC-100’’ with the sor-
bent 1000 Å; solvent—THF (1 mL/min, 25 C, PS-standard).
Polymers’ yields, their molecular mass characteristics, and
phase transition temperatures are presented in Table 2.
ꢀ
Molecular masses of homopolymers and copolymers (Mw)
were between ꢁ6000 and ꢁ10,000. Such low values of
molecular masses can be explained by the chain transfer
reaction to N¼¼N bond, as was shown in a number of
papers19,22,23 for the diverse polymers based on azobenzene-
containing monomers.
As was shown before, the copolymer containing only azoben-
zene and phenylbenzoate groups (1:1) obtained by copoly-
merization of monomers M4 and M5 is characterized by a
nematic phase with clearing temperature of about 120 ꢀC.24
Introduction of crown ether groups as side chains causes a
decrease in clearing temperatures due to their low
anisometry.
1H NMR spectra were measured on ‘‘Bruker Avance-400’’
with frequency of 400 MHz; 13C NMR spectra were mea-
sured on ‘‘Bruker AC200’’ with frequency of 200 MHz; chemi-
cal shifts were determined using TMS as standard. MS were
measured on ‘‘Finnigan LCQ’’ with electrospray ionization of
MeOH solution.
Spectral Properties of Polymer Films and Influence
of Complexation on Absorbance Spectra
Fig. 2 shows the absorbance spectra of thin films of homo-
polymers and copolymers. As is seen from the figure, homo-
polymer P1 and both copolymers are characterized by an
absorbance peak with maximum around 360–370 nm corre-
sponding to a p–p* electronic transition, whereas this peak
for homopolymer P2 is shifted to the short wavelength spec-
tral region with respect to the other polymers due to the
presence of the electron-withdrawing carboxylic group. Ab-
sorbance peaks of copolymers are practically coinciding
because they have an identical photochromic fragment. Poly-
mer P1 absorbs light at longer wavelength due to the strong
Textural observations and phase transition temperature
determinations were performed using ‘‘Polam-R112’’ polariz-
ing optical microscope equipped with ‘‘Mettler FP-86’’ hot
stage. Temperatures and enthalpies of phase transitions
were measured using a ‘‘Mettler TA-4000’’ differential scan-
ning calorimeter with heating (cooling) rates of 10 K/min;
sample weights were 5–10 mg.
Polymers films for photo-optical investigations were pre-
pared by spin coating method from chlorophorm solutions.
This method allows one to obtain thin homogeneous amor-
phous polymer films.
Complexes of polymers with potassium perchlorate were
prepared as follows. Solutions of polymers in dry THF were
added to solution of potassium perchlorate in dry acetoni-
trile. After slow evaporation of the solvents, the obtained
complexes were dried in vacuum at 100 ꢀC. In all cases, the
amount of potassium salt was equimolar to the crown ether
groups’ content.
Electronic absorbance spectra of the spin-coated polymer
films and dilute solutions were recorded on a UNICAM UV-
500 spectrometer. Photo-optical investigations were per-
formed using a specially designed setup including a diode
laser KLM-473/h-150 with wavelength 473 nm. Light inten-
sity as measured using a ‘‘LaserMate-Q’’ (coherent) intensity
meter is ꢁ2.0 W/cm2. Degree of chromophore orientation
was measured by a J&M (Tidas) spectrometer. For this pur-
pose, polarized absorbance was measured with an angle step
of 10ꢀ using Polarizer Control Unit (Owis).
FIGURE 2 Normalized absorbance spectra of photochromic
crown ether-containing homopolymers and copolymers. [Color
figure can be viewed in the online issue, which is available at
wileyonlinelibrary.com.]
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Now let us consider how complexation with metal ions influ-
ences the spectral features of thin polymers films (Fig. 3).
For all polymers, except P1, coordination with potassium
ions has no effect on either peak position or value of absorb-
ance. Complexation of P1 films with potassium perchlorate
results in a hypsochromic shift of about 8 nm [Fig. 3(a)].
The spectral shift is related to electron density displacement
in conjugated electron systems, including azobenzene chro-
mophores and oxygen atoms of crown ether ring, after coor-
dination with positively charged ions.
Introduction of a potassium cation in crown ether ‘‘cavity’’
draws off electron density from the oxygen atoms and, thus,
shifts the absorbance peak to the short-wavelength spectral
range. A similar effect was demonstrated for the low molar
mass crown ether-containing dyes.13,28
Photo-orientation Process in Thin Films of the
Homopolymers
Irradiation of thin polymer films by blue polarized laser light
(473 nm) causes the photoinduced orientation of the side
groups in a direction perpendicular to the polarization direc-
tion. This process is accompanied by the growth of linear
dichroism (eq 1 and Fig. 4). Light action on the previously
annealed film induces lower values of dichroism. It can be
explained by the formation of a multidomain LC structure.
Each separated domain has a definite orientation of side
groups, but domains are randomly oriented and the film has
no preferred optical axis (dichroism value before irradiation
is equal to zero). On the other hand, the ordered LC struc-
ture prohibits photo-orientation of the side groups. It should
be noted that independently of the thermal prehistory, the
dichroism values and orientation degree remain unchanged
under a prolonged annealing at temperatures higher than
the glass transition temperature.
FIGURE 3 Absorbance spectra of the homopolymers P1 (a),
and P2 films (b) before and after complexation with KClO4.
[Color figure can be viewed in the online issue, which is avail-
able at wileyonlinelibrary.com.]
influence of electron donor oxymethylene groups of the
crown ether fragment directly connected with the chromo-
phore. It is well known that the position of the absorbance
maximum of azobenzene derivatives depends on types of
substituents connected with chromophores.25
It is noteworthy that spectra of polymers (for fresh and
annealed films) and spectra of dilute polymer solutions are
very similar. On the other hand, it is well known that the
films of azobenzene with low molar mass and polymer sub-
stances are characterized by the formation of J- and H-aggre-
gates, which usually appear after annealing.26,27 Aggregation
processes are always accompanied by significant spectral
changes. However, for crown ether-containing homopolymers
synthesized in this work, we did not find any spectral
changes after annealing at temperatures above their glass
transitions. This probably can be explained by the absence of
any aggregation processes due to the presence of the bulky
crown ether fragments sterically preventing an interaction of
the chromophoric moieties in the homopolymers.
FIGURE 4 Dichroism growth kinetics during the polarized light
irradiation of fresh and annealed films of the homopolymer P1.
[Color figure can be viewed in the online issue, which is avail-
able at wileyonlinelibrary.com.]
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
Polarized light irradiation of P2 films also results in the
photo-orientation phenomenon (Fig. 5). Maximum values of
dichroism for both homopolymers, P1 and P2, are almost
the same. But for the polymer P2 films, the rate of the
dichroism growth is about five times lower than for P1. The
calculated rate constants, assuming first-order kinetics, are
6.9 ꢃ 10ꢂ2 sꢂ1 (P1) and 1.3 ꢃ 10ꢂ2 sꢂ1 (P2). A difference in
the rates of dichroism growth is explained by the different
absorbance at 473 nm for homopolymers (Fig. 2).
In contrast to P1, annealing of irradiated P2 films com-
pletely disrupts the side groups’ orientation (Fig. 5). More-
over, no photo-orientation phenomenon was found in the
previously annealed films. During the annealing, a significant
decrease in absorbance was found [Fig. 6(a,b)], which can be
associated with thermally induced homeotropic alignment of
the chromophores. A similar effect was already observed for
smectogenic azobenzene-containing copolymers.29 To experi-
mentally confirm this assumption, we have performed polar-
ized light absorbance measurements of the samples placed
FIGURE 5 Dichroism growth kinetics during polarized light irra-
diation of the fresh and annealed films of homopolymer P2.
[Color figure can be viewed in the online issue, which is avail-
able at wileyonlinelibrary.com.]
FIGURE 6 (a) Spectral changes of P2 film under annealing; (b) kinetics of absorbance value changes at wavelength corresponding
to p–p* electron transition of azobenzene groups (333 nm) in P2 film; (c) polar diagrams of polarized light absorbance measured
with angle of 45ꢀ between film normal and detecting light; (d) schematic representation of homeotropic orientation formation in
P2 films under annealing. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
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ARTICLE
the side groups and, consequently, the degree of uniaxial
order.
An Influence of Complex Formation on Orientation
Degree of Irradiated Films of Polymers
We have supposed that all synthesized polymers can be used
as materials for the creation of sensor devices sensitive to
the metal ions. To verify this assumption, a thin amorphous
film of the homopolymer P1 was irradiated by the polarized
light (473 nm) during 10 min [steady state; maximum
dichroism D1 ¼ 0.6, curve 1 in Fig. 8(a)]. Then, the irradiated
FIGURE 7 Dichroism growth kinetics during the polarized light
irradiation in the amorphous films of copolymer Cop15 and
‘‘model’’ copolymer Cop0 without crown ether groups and hav-
ing the same nematogenic and azobenzene side groups.22
[Color figure can be viewed in the online issue, which is avail-
able at wileyonlinelibrary.com.]
at 45ꢀ with respect to light axis. Such geometry allows one
to estimate the degree of chromophore orientation in the
direction along the normal to the film. Figure 6c shows the
polar diagram of the P2 film before and after annealing at
ꢀ
50 C during 30 min. In the fresh films no anisotropy of ab-
sorbance was found, whereas annealing induces a noticeable
value of dichroism, indicating out-of-plane orientation of the
chromophores as schematically drawn in Figure 6d.
As was shown previously,29 a homeotropic alignment in
polyacrylates having similar chromophores is provoked by
smectic phase formation. Our preliminary X-ray investiga-
tions reveal the presence of small-angle reflections corre-
sponing to a distance of about 47 Å, that confirms formation
of smectic order fluctuations in homopolymer P2. More
detailed structural studies are currently in progress to distin-
guish the formation of a low-temperature smectic phase and
the presence of cybotactic smectic fluctuations. Careful polar-
izing optical microscopy observations did not show any
changes of the marble nematic texture to focal-conic or fan-
shaped textures typical of the smectic phase.
Photo-orientation Processes in Thin Films
of Ternary Copolymers
Let us consider photo-orientation processes in the films of
the ternary copolymers. It is interesting to note that the rate
of photo-orientation in the copolymer Cop15 films is higher
than that in double copolymer Cop0 without crown ether
groups and having the same nematogenic and azobenzene
side groups.26 This difference can be explained by the lower
glass transition temperature of the copolymer having crown
ether moieties (Fig. 7). However, it is noteworthy that the
maximum achievable value of dichroism for Cop15 is much
lower. Such a difference is associated with the presence of
the bulky crown ether fragments reducing the anisometry of
FIGURE 8 (a) Polar diagrams of the polarized light absorbace
of P1 film just after photo-orientation by light action (curve 1),
and after complexation with potassium perchlorate in water
(curve 2); (b) changes of crown ether-containing group anisom-
etry under complex formation. [Color figure can be viewed in
the online issue, which is available at wileyonlinelibrary.com.]
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
film was immersed for 1 h in ꢁ10ꢂ3 M aqueous potassium
perchlorate. After this procedure, the dichroism value
decreased by half (D2 ¼ 0.3, curve 2 in Fig. 8a). It should be
stressed that the absorbance spectrum was also changed
namely, the peak position has been shifted to the short-
wavelenth spectral region that is associated with complex
formation, as discussed above. As for low-molar mass crown
ether-containing liquid crystals,30 complexation reduces the
conformational mobility of the crown ether fragment, that is,
the latter becomes more rigid (Fig. 8b). Besides, the bulky
perchlorate counter ion coordinates with positively charged
potassium cation embedded in crown ether ring due to elec-
trostatic attraction. Both factors significantly decrease the
anisometry of the side group as a whole and reduce uniaxial
photoinduced order and the value of dichroism (Fig. 8b).
2009, 47, 6472–6495; (c) Xiong, X.; Chen, Y.; Feng, S.; Wang,
W. J Polym Sci, Polym Chem Ed. 2010, 48, 3515–3522; (d)
Hmadeh, M.; Fang, L.; Trabolsi, A.; Elhabiri, M.; Albrecht-Gary,
A.-M.; Stoddart, J. F. J Mater Chem 2010, 20, 3422–3430; (e) Li,
S.; Zheng, B.; Chen, J.; Dong, S.; Ma, Z.; Huang, F.; Gibson, H.
W. J Polym Sci, Polym Chem 2010, 48, 4067–4073; (f) Lee,
Y.-G.; Koyama, Y.; Yonekawa, M.; Takata, T. Macromolecules
2010, 43, 4070–4080.
4 Kimura, K.; Sakamoto, H.; Nakamura, M. Bull Chem Soc Jpn
2003, 76, 225–245.
5 Kwon, S.; Kim, H. S. Supramolecular Chem 2007, 19,
277–281.
6 Johansson, G.; Percec, V.; Ungar, G.; Abramic, D. J Chem
Soc Perkin Trans 1994, 447–459.
7 Suarez, S.; Imbert, D.; Gumy, F.; Piguet, C.; Bunzli, J. C.
Chem Mater 2004, 16, 3257–3266.
CONCLUSIONS
8 Percec, V.; Rodenhouse, R. Macromolecules 1989, 22, 2043–
A number of novel crown ether-containing photochromic LC
polymers having different macromolecular architecture was
synthesized. It was shown that the location of crown ether
fragments with respect to the photochromic fragments influ-
ences not only the phase behavior and spectral properties
but also the kinetics of photo-orientation processes in thin
polymer films. Introduction of crown ether fragments as sep-
arated nonphotochromic side groups decreases the degree of
the photoinduced orientational order. For the first time, the
possibility of using photo-optically oriented films of crown
ether-containing polymers as sensors for metal ions was
demonstrated. It was also shown that complexation of poly-
mers by immersion in water solution of salts results in
noticeable decrease in dichroism values of the films. This
effect is promising for the creation of polymer-based sensor
films and coatings.
2047.
9 Fischer, H. Mol Cryst Liq Cryst 1994, 238, 249–253.
10 Percec, V.; Johansson, G.; Rodenhouse, R. Macromolecules
1992, 25, 2563–2565.
11 Percec, V.; Rodenhouse, R. J Polym Sci Part A: Polym Chem
1991, 29, 15–28.
12 Alfimov, M.; Fedorova, O.; Gromov, S. J Photochem Photo-
biol Part A: Chem 2003, 158, 183–198.
13 Ushakov, E.; Alfimov, M.; Gromov, S. Russ Chem Rev 2008,
77, 39–58.
14 Tokuhisa, H.; Kimura, K.; Yokoyama, M.; Shinkai, S. J Chem
Soc Faraday Trans 1995, 91, 1237–1240.
15 Shibaev, V.; Bobrovsky, A.; Medvedev, A. Russ Chem Bull
2007, 12, 2332–2343.
This research was supported by the Russian Foundation of Fun-
damental Research (08-03-00481) and Program COST-D35.
16 Shibaev, V.; Medvedev, A.; Bobrovsky, A. J Polym Sci Part
A: Polym Chem 2008, 46, 6532–6541.
17 (a) Smart Light Responsive Materials. Azobenzene-Contain-
ing Polymers and Liquid Crystals; Zhao, Y.; Ikeda, T., Eds.;
Wiley: New Jersey, 2009; (b) Zebger, I.; Rutloh, M.; Hoffmann,
U.; Stumpe, J.; Siesler, H. W.; Hvilsted, S. J Phys Chem, Part
A 2002, 106, 3454–3462; (c) Zebger, I.; Rutloh, M.; Hoffmann,
U.; Stumpe, J.; Siesler, H. W.; Hvilsted, S. Macromolecules
2003, 36, 9373–9382; (d) Jung, C. C.; Rosenhauer, R.; Rutloh,
M.; Kempe, C.; Stumpe, J. Macromolecules 2005, 38,
4324–4330; (e) Eich, M.; Wendorff, J. H.; Reck, B.; Ringsdorf,
H. Macromol Chem, Rapid Commun 1987, 8, 59; (f) Eich, M.;
Wendorff, J. H. Macromol Chem, Rapid Commun 1987, 8,
467–471; (g) Sanchez, C.; Alcala, R.; Hvilsted, S.; Ramanujam,
P. S. Appl Phys Lett 2001, 78, 3944–3946; (h) Sanchez, C.;
Alcala, R.; Hvilsted, S.; Ramanujam, P. S. Appl Phys Lett 2000,
77, 1440–1442.
REFERENCES AND NOTES
1 Hiraoka, M. Crown Compounds. Their Characteristics and
Applications; Elsevier: Amsterdam, 1982.
2 (a) Takata, T.; Kihara, N.; Furusho, Y. Adv Polym Sci 2004,
171, 1–75; (b) Collin, J.-P.; Heitz, V.; Sauvage, J.-P. Top Curr
Chem 2005, 262, 26–62; (c) Huang, F.; Gibson, H. W. Prog Poly
Sci 2005, 30, 982–1018; (d) Lankshear, M. D.; Beer, P. D. Acc
Chem Res 2007, 40, 657–668; (e) Griffiths, K.; Stoddart, J. F.
Pure Appl Chem 2008, 80, 485–506; (f) Harada, A.; Hashidzume,
A.; Yamaguchi, H.; Takashima, Y. Chem Rev 2009, 109,
5974–6023; (g) Gassensmith, J. J.; Baumes, J. M.; Smith, B. D.
Chem Commun 2009, 42, 6329–6338; (h) Crowley, J. D.;
Goldup, S. M.; Lee, A.-L.; Leigh, D. A.; McBurney, R. T. Chem
Soc Rev 2009, 38, 1530–1541; (i) Niu, Z.; Gibson, H. W. Chem
Rev 2009, 109, 6024–6046.
18 Boiko, N.; Shibaev, V.; Kozlovsky, M. J Polym Sci 2005, 43,
2352–2360.
19 Kostromin, S.; Stakhanov, A.; Shibaev, V. Polym Sci Ser A
3 (a) Gibson, H. W.; Farcas, A.; Jones, J. W.; Ge, Z.; Huang, F.;
Vergne M.; Hercules, D. M. J Polym Sci, Polym Chem Ed. 2009,
47, 3518–3543; (b) Gibson, H. W.; Ge, Z.; Jones, J. W.; Harich,
K.; Pederson, A.; Dorn, H. C. J Polym Sci, Polym Chem Ed
1996, 38, 1030–1039.
20 Vogel, A. I.; Tatchell, A. R.; Furnis, B. S.; Hannaford, A. J.;
Smith, P. W. G. Vogel’s Textbook of Practical Organic
632
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
Chemistry; Longman Scientific & Technical: England, 1989, pp
948–950.
26 Photoreactive Organic Thin Films; Sekkat, Z.; Knoll, W.;
Eds.; Academic Press: San Diego, 2002; p 68.
21 Portugall, M.; Ringsdorf, H.; Zentel, R. Makromol Chem
27 Zweck, J.; Penzkofer, A. Chem Phys 2001, 269, 399–409.
1982, 183, 2311
28 Alfimov, M.; Fedorov, Y.; Fedorova, O.; Gromov, S.; Hester,
R.; Lednev, I.; Moore, J.; Oleshko, V.; Vedernikov, A. J Chem
Soc Perkin Trans 1996, 2, 1441–1447.
22 Nuyken, R. Adv Polym Sci 1986, 73, 145–199.
23 Hallensleben, M.; Weichart, B. Polym Bull 1989, 22, 553–556.
29 Bobrovsky, A.; Shibaev, V. J Photochem Photobiol Part A:
24 Bobrovsky, A.; Ryabchun, A.; Medvedev, A.; Shibaev, V.
Chem 2005, 172, 140–145.
J Photochem Photobiol Part A: Chem 2009, 206, 46–52.
25 Durr, H.; Bouas-Laurent, H. Photochromism, Molecules and
30 He, G.-X.; Wada, F.; Kikukawa, K.; Shinkai, S.; Matsuda, T. J
Systems; Elsevier: Amsterdam, 2003
Org Chem 1990, 55, 541–548.
CROWN ETHER- AND AZOBENZENE-CONTAINING LCP, RYABCHUN ET AL.
633