High Efficiency Luminescent Liquid Crystalline Polymers Based on Aggregation-Induced Emission and "jacketing" Effect: Design, Synthesis, Photophysical Property, and Phase Structure

Article abstract of DOI:10.1021/acs.macromol.7b01605

A series of high efficiency luminescent liquid crystalline polymers (LLCPs) based on aggregation-induced emission (AIE) and the "Jacketing" effect, namely, poly{2,5-bis{[2-(4-oxytetraphenylethylene)-n-alkyl]oxycarbonyl}styrene} (denoted as Pm, m = 2, 4, 6

Full text of DOI:10.1021/acs.macromol.7b01605

Article
Cite This: Macromolecules XXXX, XXX, XXX−XXX
High Efficiency Luminescent Liquid Crystalline Polymers Based on
Aggregation-Induced Emission and “Jacketing” Effect: Design,
Synthesis, Photophysical Property, and Phase Structure
†
,‡
§
†
§
†
†
,‡
Yang Guo, Dong Shi, Zhi-Wang Luo, Jia-Ru Xu, Ming-Li Li, Long-Hu Yang, Zhen-Qiang Yu,*
§
,†
Er-Qiang Chen, and He-Lou Xie*
†Key Laboratory of Advanced Functional Polymer Materials of Colleges and Universities of Hunan Province, College of Chemistry,
Xiangtan University, Xiangtan 411105, Hunan Province, China
‡
Shenzhen Key Laboratory of Functional Polymers, School of Chemistry and Environmental Engineering, Shenzhen University,
Shenzhen 518060, China
§
Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering,
Peking University, Beijing 100871, China
*
S Supporting Information
ABSTRACT: A series of high efficiency luminescent liquid crystalline polymers
LLCPs) based on aggregation-induced emission (AIE) and the “Jacketing” effect,
namely, poly{2,5-bis{[2-(4-oxytetraphenylethylene)-n-alkyl]oxycarbonyl}styrene}
denoted as Pm, m = 2, 4, 6, 8, 10, 12), were successfully designed and synthesized
(
(
via introducing tetraphenylethylene to the side group with different length spacers.
Because of the AIE effect, the resultant LLCPs are completely free of aggregation
caused quenching. The photophysical properties and phase behavior were studied
via various techniques such as UV−vis absorption spectra, photoluminescence
spectra (PL), polarized light microscopy (PLM), differential scanning calorimetry
(
DSC), and variable temperature one-dimensional wide-angle X-ray diffraction (1D
WAXD). The results revealed that the resultant monomers showed typical AIE
behavior and the polymers exhibited aggregation enhanced emission (AEE)
behavior. Moreover, due to the “Jacketing” effect, the polymers showed high
efficiency luminescence in the liquid crystalline state, which was significantly dependent on the spacer length (the solid-state
quantum yields decreased from 52% to 18% with increasing spacer length). Meanwhile, the glass transition temperatures (Tg)
decreased with increasing the length of spacers. With increasing the spacer length, the phase structure transformed from smectic
A (SmA) (Pms, m = 2, 4, 6) to hexagonal columnar phase (Col ) (Pms, m = 8, 10, 12). All the polymers presented good film-
H
forming property and processing performance, which made them be promising materials for the luminescent devices.
2
6−34
INTRODUCTION
solvents.
At present, many AIE luminogens have been
■
35−41
successfully developed through rational molecular design.
Luminescent liquid crystals (LLCs) combining intrinsic light-
emitting property and liquid crystalline ordering have been
attracted growing interests in the past decades because of their
potential applications as emissive liquid crystal displays (LCD),
organic light-emitting diode (OLED), sensors, and optical
For example, when AIE luminogens are introduced into LCs, it
may effectively resolve the conflicts between fluorophor
quenching and the necessary ordered molecular packing for
liquid crystallinity. Nowadays, most of the methods to fabricate
the LLCs with stable LC ordered structure and high solid-state
emission efficiency adopt the simple approach using the AIE-
active dye as core and conventional mesogens as periphery, and
the resultant LLCs can result in different supramolecular phase
structures, such as columnar, nematic, smectic A (SmA), or
1
−6
information storage.
Particularly, LLCs can emit linear or
4
,7−12
circular polarized luminescence (CPL) after orientation.
Thus, some devices fabricated by this kind of material can show
deeper color saturation, wider viewing angle, higher contrast
ratio, and lower power consumption. However, the preparation
of LLCs is a challenging problem because the regularly packed
chromophoric mesogens lead to the aggregation caused
42−47
smectic C (SmC) phase.
Tetraphenylethylene (TPE) is a typical AIE luminogen with
high solid-state efficiency and highly twisted structure, which
has been extensively employed as luminogen to construct LLCs
13−21
quenching (ACQ) effect.
Different from ACQ, aggregation-induced emission (AIE)
2
2−25
phenomenon
is that the aggregation leads to enhancing
the emission of weak fluorophor or even nonluminescent
molecules when these molecules are aggregated into particles in
poor solvents or fabricated into solid state from good
Received: July 27, 2017
Revised: December 2, 2017
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.macromol.7b01605
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4
8−51
1
due to its facile synthesis and versatile functionalization.
monomers and polymers have been confirmed by FTIR, H
13
Incorporating LC mesogens into TPE molecule may be the
most efficient method to construct LLCs, and the phase
structure of the resultant LLCs is strongly dependent on the
structure of the LC mesogens. For example, Tang and co-
workers designed and synthesized a series of LLC polymers
LLCPs) containing biphenyl and TPE units by click
polymerization because the biphenyl groups could be easily
packed to form LC phase and TPE group could be forced to be
packed in the confined space; thus, the resultant LLCPs
showed both high solid-state efficiency and LC prop-
NMR, C NMR, mass spectral, and elemental analysis, and the
molecular weight of the polymers determined by gel
permeation chromatography (GPC). UV−vis and photo-
luminescence spectra (PL) results indicated that the monomers
were AIE active and polymers exhibited AIE or aggregation
enhanced emission (AEE) characteristics. Further, on the basis
of polarized light microscope (PLM), differential scanning
calorimetry (DSC), and wide-angle X-ray diffraction (WAXD)
results, we found that the LLCPs formed SmA (Pms, m = 2, 4,
4
9
(
6) or hexagonal columnar phase (Col ) (Pms, m = 8, 10, 12).
H
4
8,49,52−57
erty.
Different from the generally method of synthesizing LLCPs
by copolymerizing mesogens and luminogens, herein, we
propose a new approach to fabricate LLCPs based on AIE
and the side-chain “Jacketing” effect. According to the previous
EXPERIMENTAL SECTION
■
Materials. 1,12-Dibromododecane, 1,10-dibromodecane, 1,8-di-
bromooctane, 1,6-dibromohexane, 1,4-dibromobutane, 1,2-dibromo-
ethane, benzophenone, 4-hydroxybenzophenone, zinc powder, and
titanium tetrachloride were purchased from Energy Chemical and
directly used. Tetrahydrofuran (THF) was refluxed over sodium and
distilled before use. Acetone, N,N-dimethylformamide (DMF),
potassium carbonate, and potassium bicarbonate were purchased
from Guangdong Guanghua Sci-Tech Co., Ltd., and were used
directly. 2,2-Azobis(isobutyronitrile) (AIBN) was purified by
recrystallization using ethanol as solvent. 2-Vinyl-p-biphthalic acid
5
8,59
works,
mesogen-jacketed liquid crystalline polymers
(
MJLCPs) are a kind of LCPs with bulky side group directly
attached to the polymer main chain or via very short spacer,
whether the bulky side group is mesogenic or not. Because of
the spatial requirement of the bulky side groups, the whole
polymer chain is enforced to take extended conformation along
the main-chain direction. Thus, the resultant polymer chain
forms a cylinder-like or ribbon-like single conformational unit
because the side groups and the backbone of MJLCPs almost
60
64
was synthesized in our lab.
Instruments and Measurements. 1H NMR and 13C NMR
experiments were carried out on a Bruker ARX400 spectrometer,
6
1−63
merge together.
We anticipate that when the periphery of
where deuterated chloroform (CDCl ) was used as the solvent and
3
MJLCP is modified by TPE, the rigid MJLCP will restrict the
intramolecular rotation of TPE and the resultant LLCPs will
form luminescent columnar or smectic structure.
With this in mind, we designed and successfully synthesized
poly{2,5-bis{[2-(4-oxytetraphenylethylene)n-alkyl]-
oxycarbonyl}styrene} (denoted as Pm, m = 2, 4, 6, 8, 10, 12).
The chemical structure is shown in Scheme 1. Pm can be easily
tetramethylsilane (TMS) as the internal standard. Fourier transform
infrared spectroscopy (FTIR) spectra were recorded in KBr pellets on
a PE Spectrum One FTIR spectrometer. Mass spectral and elemental
analysis experiments were performed on Autoflex III and Varlo EL III,
respectively. A GPC (Waters GPC1515) experiment was carried out to
determine the apparent number-average molecular weight (M ) and
n
molecular weight distribution (M /M ), where THF was used as the
w
n
eluent and the linear polystyrene as standard was used to calibrate the
standard curve.
Scheme 1. Molecular Structures of the LLCPs (Pms)
UV−vis absorption spectra were recorded on a Cary 100 using the
Flashing xenon lamp as the light source. Emission spectra were
measured on a spectrofluorometer QM40 in the right-angle geometry
with 1 cm quartz cuvettes. The wavelength of the excitation light fixed
was λex = 365 nm, and the slit width of 5 nm was used for both
monochromators. The quantum yields (Φ ) in the solid state were
F’s
determined using an integrating sphere on a Nanolog FL3-2iHR
infrared fluorescence spectroscopy equipped with R928 photo-
multiplier as detector.
Thermogravimetric analysis (TGA) was carried out on a TA SDT
2960 instrument under a nitrogen atmosphere at a heating rate of 20
°C/min. DSC experiment was performed on a TA DSC Q100
achieved via radical polymerization due to the monomers
containing polymerizable vinyl. The chemical structures of the
Scheme 2. Synthetic Route of the Monomers and Polymers
B
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calorimeter with a programmed heating procedure in nitrogen. The
LC texture of the samples was investigated under PLM (Leica DM-
LM-P), which was equipped with a Mettler FP82HT hot stage. 1D-
WAXD powder curves were recorded on a Bruker D8 advance
diffraction equipped with a temperature control unit (Paar Physica
TCU 100). In WAXD experiment, the sample was set horizontally on
the stage and the silver behenate (2θ < 10°) was used to calibrate the
reflection peak position.
Synthesis. The synthetic route of Pms and monomers (Mms) is
shown in Scheme 2. The syntheses of different monomers and
polymers were similar; herein we use 2,5-bis{[2-(4-oxy-tetraphenyl-
ethylene)-6-hexane]oxycarbonyl}styrene (M6) and the corresponding
P6 as the example to elucidate this synthetic process. The detailed
synthesis information was described as follows. For other monomers
and polymers, the relevant synthetic data are presented in the
Supporting Information.
1491.57, 759.93, 746.77, 696.18 (−Ar), 1716.25 (CO), 1174.06
(C−O−C), 1387.71, 842.45 (−CC−). Anal. Calcd for C H O :
7
4
68
6
C, 84.41, H, 6.46, O, 9.13. Found: C, 84.45, H, 6.80, O, 8.75. MS:
MALDI-TOF MS (CCA matrix in THF, laser λ = 337 nm, + mode)
•
+
for C H O calcd 1052.5 Da, found m/z 1052.5 [M] .
74
68
6
Synthesis of Poly{2,5-bis{[2-(4-oxytetraphenylethylene)-
hexane]oxycarbonyl}styrene}(P6). 1.052 g (1 mmol) of M6, 1
mg/mL chlorobenzene solution of AIBN (0.1 mL), and chloroben-
zene (1.0 mL) were transferred into a reaction tube; the tube was
purged with nitrogen, subjected to three freeze−thaw cycles to remove
oxygen, and then sealed off under vacuum. The polymerization
reaction was carried out at 90 °C for 24 h. Afterward, after opening the
tube, the reaction product was diluted with 30 mL of THF. The
resultant substance was precipitated in methyl alcohol. To completely
remove the unreacted monomers, the precipitated procedure was
repeated several times until the monomer peak could not be detected
1
by H NMR. The product was dried under vacuum. Yield: 85%.
Synthesis of 4-Hydroxytetraphenylethylene. The mixture of
benzophenone (2 g, 10 mmol), 4-hydroxybenzophenone (2.2 g, 12
mmol), zinc powder (2.9 g, 44 mmol), and THF (200 mL) was added
RESULTS AND DISCUSSION
■
into a 500 mL round-bottom flask. After stirring for 0.5 h, TiCl (2.5
4
Synthesis and Characterization of the Monomers and
Polymers. The monomers were successfully synthesized
through multistep reactions according to Scheme 2, and their
chemical structures were confirmed by various characterization
techniques. All monomers with vinyl could be polymerized
readily using the radical polymerization method. The resultant
polymers presented the sufficient large molecular weight (MW)
to eliminate the effect of MW on the phase behavior and
luminescent property. Both the monomers and polymers are
well soluble in common organic solvents such as toluene, THF,
mL, 22 mmol) was added to round-bottom flask dropwise under a N2
atmosphere in salt−ice bath conditions. One hour stirring later, the
reaction was refluxed for 12 h. When the reaction mixture was cooled
to 25 °C, 10% aqueous K CO solution (100 mL) was dropped into
2
3
the mixture and then vigorously stirred for 5.0 min. Afterward, the
dispersed insoluble material was removed by filtrating. The mixed
solution was extracted with CH Cl (3 × 50 mL), and the organic
2
2
layer was collected. The combined organic fractions were washed with
water and dried with Na SO . The solvent of the combined organic
2
4
fractions was removed by rotary evaporators. The crude product was
further purified by column chromatography with silica gel as adsorbed
phase and with petroleum ether/CH Cl (5:1, v/v) as eluent. The
1
chloroform, and chlorobenzene. As shown in Figure 1 of H
2
2
1
resultant product (TPE-OH) is white solid with the yield of 44.2%. H
NMR (DMSO-d ) δ (ppm): 9.35 (s, 1H, −OH), 7.1 (d, 9H), 6.98 (s,
6
6
H), 6.73 (s, 2H), 6.51 (s, 2H).
Synthesis of ω-(4-Tetraphenylethylene-yloxy)-1-bromohex-
ane. The mixture of 4-hydroxytetraphenylethylene (3 g, 8.6 mmol),
1
0
,6-dibromohexane (5 mL, 0. 013 mol), potassium carbonate (1.79 g,
.013 mol), and 100 mL of acetone was added into a 250 mL round-
bottom flask with continuous magnetic stirring at 60 °C overnight.
After the reaction was complete, the product was dropped into cold
water to precipitate and then filtered. The crude product was purified
by recrystallization with petroleum ether to yield the white powder.
1
Yield: 80%. H NMR (CDCl ) δ (ppm): 7.13−7.07 (m, 9H), 7.05−
3
6
.99 (m, 6H), 6.91−6.87 (m, 2H), 6.59−6.54 (m, 2H), 3.88 (m, 2H,−
OCH −), 3.42 (m, 2H, −OCH −Br), 1.95−1.85 (m, 2H, −CH −),
2
2
2
1
.80−1.71 (m, 2H, −CH −), 1.50 (m, 4H, −CH −).
2
2
Synthesis of 2,5-Bis{[2-(4-oxytetraphenylethylene)hexane]-
oxycarbonyl}styrene (M6). 2-Vinyl-p-biphthalic acid (0.7 g, 40
mmol), KHCO (5.0 g, 50 mol), ω-(4-tetraphenylethyleneyloxy)-1-
3
bromohexane (4.1 g, 80 mmol), and 100 mL of N,N-dimethylforma-
mide (DMF) were added into a 250 mL bottom flask, and the mixture
was reacted at 100 °C for 24 h. Afterward, the reaction mixture was
cooled to room temperature and pump filtered. The filter liquor was
poured slowly into cold water, and then solid precipitation was further
pump filtered. The crude product was purified by column
1
Figure 1. H NMR spectra of M6 and P6.
NMR, the resonance signals of M6 at 8.26 ppm (peak e) and
.93 ppm (peak d) are the characteristic peaks of hydrogen
7
displacement of the benzene ring linked with a vinyl group,
those at 5.4 ppm (peak a), 5.8 ppm (peak b), and 6.6 ppm
(peak c) are characteristic peaks of vinyl substituent, and those
at the 6.93−7.28 ppm (peak l, m, n, o, p, q, r, s, t) are the
characteristic peaks of hydrogen displacement of TPE. The area
ratios of all peaks are well consistent with the number of
hydrogen atoms. For P6, the distinct variation is the
disappearance of the peak (a, b, c) of the vinyl substituent.
In the meantime, some peaks of P6 become quite broad
compared to the corresponding peaks of M6, consistent with
the expected polymer structure. The detail results of other
monomers and polymers are shown in the Supporting
Information. GPC was further used to determine the MWs
chromatography, and a white solid product was obtained. Yield:
1
7
0%. H NMR (CDCl ) δ (ppm): 8.26 (s, 1H, Ar−H), 7.99 (d, 2H,
3
Ar−H), 7.13−7.00 (m, 31H), 6.93 (m, 4H), 6.63 (m, 4H), 7.38 (s, 1
H, −CHCH ), 5.75 (d, 1 H, −CHCH ), 5.42 (d,1 H, −CH
2
2
CH ), 3.88 (m, 4H, −OCH −), 3.42 (m, 4H, −OCH −), 1.95−1.85
2
2
2
(
m, 4H, −CH −), 1.80−1.71 (m, 4H, −CH −), 1.50 (m, 4H,
2
2
1
3
−
CH −), 1.77 (m, 4 H, −CH −). C NMR: 166.8 (C
̲
O), 165.7
C−), 139.57−140.5
−CC), 134.91 (aromatic
−CC), 131.36, 130.31, 128.09, 127.71,
27.61, 126.37, 126.25 (TPE C), 117.79 (aromatic C), 113.54
TPEC, C H −), 65.14 (−OCH −), 65.14
−CC), 67.00 (TPE−OC
−OCH − aromatic), 25.55−25.98 (−C
2
2
(
(
C
1
(
(
9
C
̲
O), 157.41 (TPE C
C−C), 136.18 (phenyl C
−CO), 132.58 (C
−O), 144.04 (TPE −C
̲ ̲
TPE C−C
̲
̲
̲
̲
̲
̲
̲
̲
2
2
̲
−1
̲
H −). IR (ATR, cm ): 3051,
2
2
85.57 (HCCH ) 2930.51, 2857.41 (−CH −), 3051.32, 1603.64,
2
2
C
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and the polydispersity index of Pm (GPC curves is shown in
Figure S1), and the relevant data are outlined in Table 1.
birefringence could be observed and did not disappear before
decomposition during heating (see Figure 3a−c), and during
cooling the birefringence always maintained. For P8, P10, and
P12 with longer flexible spacer, no birefringence was observed
during the whole heating process, but applying shear force, the
birefringence phenomena immediately appeared (see Figure
Table 1. GPC, DSC, and TGA Result of Pm (m = 2, 4, 6, 8,
1
0, 12)
sample yield (%) Mn,GPC (×105) M /M
a
b
b
n
Tg (°C) Td,N2 (°C)
c
d
w
3
d−f). We speculated that the LC domains in these polymers
P2
95
85
85
87
88
86
4.03
4.12
3.96
4.82
5.21
4.76
1.72
1.56
1.72
2.01
2.13
1.78
122
95
79
69
57
51
377
365
355
364
359
were too small to be observed, and the external stimuli could
induce the small LC domains agglomerate to enough bigger
domain. Once the bigger domain formed, it could be always
maintained during cooling. This phenomenon might imply the
polymers formed two different supramolecular ordered
structures.
P4
P6
P8
P10
P12
352
a
b
c
According to weight calculation. From GPC instrument. From
d
While DSC and PLM experiments did not provide more
information on the phase behavior of Mms and Pms, we carried
out the temperature-variable 1D-WAXD experiments to
elucidate phase structures and insight into their molecular
packing. The results revealed all monomers were amorphous,
and all polymers showed supramolecular ordered structures.
Figure 4a,b illustrates two sets of 1D-WAXD diffractogram of
the as-cast film of P2. During the first heating process, at 30 °C
two peaks in the low-angle region at 2θ = 3.44° and 6.79° and
one diffused halo in the high-angle region at approximately 2θ
DSC at a rate of 10 °C/min under heating. The temperature at 5.00%
weight loss.
Phase Transitions and Supramolecular Ordered
Structures. The thermal stability of Pms (m = 2, 4, 6, 10,
12) was investigated by TGA. The results indicated that the
temperatures at 5% weight loss for all polymers were higher
than 350 °C in nitrogen atmosphere, implying that these
LLCPs showed very good thermal stabilities. Subsequently,
DSC experiments were performed to investigate phase
transitions of the monomers and polymers. To erase the
thermal history, all the samples were first heated to 260 °C at a
rate of 20 °C/min followed by isothermal annealing for 10 min.
Then, the first cooling trace and the second heating trace were
recorded at 10 °C/min. For all monomers and polymers only a
=
20° were observed. The ratio of the diffraction vectors of the
low-angle peaks was 1:2, which indicated smectic phase with a
period of 2.56 nm. The high-angle amorphous halo indicated
the subnanometer structure was disordered. Presuming the
alkyl spacer was all-trans, the calculated molecular width was
3
.3 nm, and the width of TPE molecular was 0.69 nm; thus, we
single glass transition temperature (T ) could be observed
g
could speculate P2 formed the SmA phase with TPE
interdigitated each other. During the whole heating cooling
process, both the low-angle peaks and the high-angle halo
always remained unchanged. The ratio of the vectors of the
diffraction peaks q :q also remained as 1:2, indicating the stable
during the heating or cooling process (see Figure 2 and Figure
60
S2), similar to that found in other MJLCPs. Meanwhile, the
glass transition temperature (T ) for the polymers gradually
g
decreased with increasing the alkyl spacer length, which meant
that increased alkyl spacer length could lead to better molecular
mobility. The detailed information is shown in Table 1. The
result well agreed with the previous works about the ionic
1
2
smectic phase in whole temperature range. Figure 4c,d shows
the 1D-WAXD diffractogram of P6. Two peaks were showed in
the low-angle region at 2θ = 3.13° and 6.31° in addition to a
one diffuse halo in the high-angle region. Likewise, the
diffraction position hardly changed during both heating and
cooling process. A similar result of P4 is shown in Figure S3a,b.
64,65
polymeric liquid crystals (IPLCs).
PLM results revealed that at room temperature all samples
could not show birefringence phenomenon. For P2, P4, and
P6, with temperature increased to higher than T , the distinct
g
Figure 2. DSC thermograms of Pms (m = 2, 4, 6, 10, 12) at a rate 10 °C/min during the processes of the first cooling (a) and the second heating
b).
(
D
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Figure 3. Representative textures of P2 (a), P4 (b), P6 (c), P8 (d), P10 (e), and P12 (f) at 140 °C (200× magnification).
Figure 4. 1D WAXD profiles of P2 recorded at various temperatures upon heating (a) and cooling (b) and P6 recorded at various temperatures
upon heating (c) and cooling (d).
The results indicated P4 and P6 also showed a similar smectic
phase.
diffraction peaks at 2θ = 3.11°, 5.44°, and 6.33° and an
amorphous halo at 2θ = 20°. The ratio of the scattering vectors
of the three diffraction peaks in the low-angle region was
With the increase of the spacer length, P8, P10, and P12
showed similar phase structure, which are different from that of
P2, P4, and P6. The temperature-variable 1D-WAXD diffracto-
grams of the as-cast film of P8 are shown in Figure 5. During
the first heating process, at 30 °C there were three low-angle
1/2
1:3 :2, suggesting the LC structure of hexagonal columnar
(Col ) phase. With increasing the temperature, the intensity of
H
the first-order peak increased slightly, and the second- and
third-order peaks became more obvious. Similar to the samples
E
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Figure 5. 1D WAXD profiles of P8 recorded at various temperatures upon heating (a) and cooling (b).
Figure 6. Schematic of the smectic structure and the Col structure of Pms.
H
P4 and P6 discussed above, the diffraction peaks and halo
remained unchanged during the whole temperature-variable
temperature. In this system, however, we found the as-cast film
could form LC ordered structure, meaning the solvent could
induce the ordered structure formation. We presume that it is
due to that the strong aggregation of TPE molecules facilitates
the formation of the ordered structures in the as-cast film.
Photophysical Properties. The photophysical properties
of the monomers and the corresponding polymers were
investigated in THF solution and thin film. The absorption
spectra of THF solutions of Mms and Pms at a concentration of
10 mol/mL are shown in the Supporting Information. The
maximum absorption for the solutions of monomers occurred
at 246 and 316 nm, which was attributed to the typical
absorption of TPE group (see Figure S4a). After polymer-
ization, the polymers solutions exhibited nearly the same
absorption behavior as that of the monomers (see Figure S4b).
This was mainly due to the structural similarity. Note that the
TPE luminogens were separated from the polystyrene back-
bone by the alkyl spacers, which hindered their electronic
interactions.
process. That meant P8 formed the stable Col phase during
H
the whole temperature-variable region. For P10 and P12, they
also formed ColH phase at different temperatures, and they
showed a similar transition during the heating process. The
detailed information is shown in Figure S3c−f.
The WAXD results revealed that Pms could form two
different types of LC phases, i.e., SmA and ColH phase,
depending on the length of the alkyl spacers (see Figure 6).
The phase behavior of Pms was similar to that we previously
−5
65
reported for ILCPs with different the flexible spacer length.
Thus, for P2, P4, and P6, the short flexible spacer between side-
group TPE and polystyrene backbone resulted in the main
chain and side chain as an integral to form a ribbon-like
molecule. In this case, the TPE groups interdigitatedly packed,
which favored forming smectic phase. For P8, P10, and P12,
because of the long alkyl spacers, the side-group TPE
decoupled from the main chain, the main chain of the
polystyrene derivative formed column structure, and the side-
group TPE surrounded the main chain. Thus, the molecules of
P8, P10, and P12 preferred to form cylinders as a whole, and
Because of the incorporation of the AIE luminogens, the
monomers and polymers were expected to be AIE or AEE
active. First, the emission behaviors of monomers were
investigated in solvent/nonsolvent mixtures. Herein, the M6
was used as example to illustrate this process. No luminescence
could be observed in THF solution (see Figure 7). However,
then the cylinders packed to form the Col phase. Moreover, it
H
is worth noting that as-cast MJLCPs are often amorphous, and
their LC structural development requires the treatment of high
F
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Figure 7. (a) Emission spectra of M6 in THF/H O with varied water content. (b) Plots of I/I values depended on water content at 476 nm for M6;
2
0
the inset photos of M6 taken under UV light in THF with 0 and 90% water contents.
Figure 8. (a) Emission spectra of P6 in THF/H O mixtures with varied water fractions. (b) Plots of I/I values versus water contents of the aqueous
2
0
mixtures at 476 nm for P6; the inset photos of in THF with 0 and 90% water fractions taken under UV light.
with gradually adding water into the THF solution, when water
content achieved 40%, the mixture begins to turn on the
emission. Further increasing the water content could distinctly
enhance its luminescence evidenced by the PL spectra. When
the water content achieved 80%, the emission intensity with the
maximum at 476 nm was approximately 20-fold than that in the
THF solution. Furthermore, when the water content achieved
maximum at 476 nm of P6 in the mixture solvent were
approximately 15- and 20-fold than that in the THF solution,
respectively. When the water content achieved 90% in the
aqueous mixtures, the emission intensity was 66-fold higher
than that in THF solution. The analogous experimental
phenomenon has been observed in other polymers (see Figure
S6). However, compared with the emission behavior of all
polymers in THF solution, it could be found that P8, P10, and
P12 were hardly luminescent, but P2, P4, and P6 could emit
weakly.
We found that the emission efficiency for both the
monomers and polymers had the dependence of molecular
structures. Figures S7a and S7b show the emission spectra at
90% water content of the monomers and polymers,
respectively. Overall, the monomers had the emission intensity
decreased with the increase of the spacer length between the
TPE and the styrene headgroup. For the polymers, the
emission intensity also gradually decreased with the increase
of the spacer length. However, for the solution with the same
molar concentration of TPE group, the comparison of the
values of PL intensity suggested that the emission of the
polymers was much stronger than that of the monomers. The
90%, the emission intensity with the maximum at 476 nm
underwent a drastic increase, which arrived almost 160-fold
than that in the THF solution. Because of the benzene ring
connecting to the vinyl emitted in the UV region, the visible
emission of M6 should be attributed to the TPE units.
Likewise, other monomers were also nonluminescence in THF
solution, and the addition of water resulted in AIE behaviors
(detailed information is shown in Figure S6).
Sequentially, the AIE behaviors of the polymers were also
investigated. As shown in Figure 8, P6 was extremely weak
luminescent in THF solution but exhibited the sky-bluish
emission with the maximum at 476 nm in the THF/water
mixture solution. The emission intensity gradually enhanced
with increasing the water content in the mixture solution. For
70% and 80% water content, the emission intensity with the
G
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value of the emission intensity of the polymers was
approximately ∼10 times larger than that of the corresponding
monomers. Meanwhile, the data shown in Figure S7 also
indicated the increments with the decrease of spacer length for
polymers were much higher than that of the monomers.
For insight into the relationship between luminescent
behavior and chemical structures, each emission curve of the
above-mentioned emission spectra at 90% water content were
integrated, which was directly dependent on the emission
efficiency. The values of the integral areas showed a similar
tendency as that discussed above, which is shown in Figure 9.
for P2−P12, which were 1 order of magnitude higher than that
of monomers. As described above, all polymers showed
supramolecular ordered structure, which meant they could
strongly emit in the LC state.
Figure 10 shows that the Φ values of solid Pms decreased
F’s
with increasing the spacer length, which was in good agreement
Figure 10. Relationship of Pms between the quantum yields (Φ )
F’s
and the spacer length.
with the variation tendency in the solution mentioned above.
The WAXD experiments revealed P2−P6 and P8−P12 showed
SmA phase and Col phase, respectively. Evidently, the Φ of
Figure 9. Integral area of emission spectra at 90% water content of the
aqueous mixtures for monomers and polymers.
H
F’s
the polymers in SmA phase was higher than that of polymers in
the Col phase. We estimated that the relatively higher Φ for
The integral areas of both the monomers and polymers
decreased with the length of spacer increased, and the values of
polymers were also much larger than those of the monomers.
Clearly, the emission efficiency of the polymers was
significantly enhanced compared to that of their corresponding
monomers. The enhancement of the emission efficiency for the
polymers mainly attributed to the spatial hindrance of the
intramolecular rotation of the side-chain TPE groups. On the
other hand, for both monomers and polymers, the emission
intensity gradually receded with increasing the length of spacer,
but the attenuation degree for monomers was significantly less
than that of the corresponding polymers. For monomers, the
main reason for the attenuation was that the incorporation of
electronically saturated alkyl chains was harmful to the TPE
aggregation formation and the long alkyl chains more easily
reduced the light emissions. For the polymers, in addition to
the reason above-mentioned, the more important reason would
be the spatial limitation of volume effect in these polymers.
Increasing the length of spacers improved the mobility of the
TPE luminogens, which resulted in the reduction of AIE effect.
Thus, compared with the monomers, the polymers showed
more obvious attenuation of AIE effect with the change of the
spacer length.
H
F’s
m ≤ 6 was because that TPE groups could form interdigitated
packing in the SmA phase, of which TPE groups were squeezed
by the quite rigid environment. In the columnar phase of Pms
with m ≥ 8, the TPE groups were located at the periphery of
the column. This spatial arrangement provided the TEP groups
more interfacial area in comparison to that in SmA phase.
Consequently, the phenyl rings could be rotated more freely,
6
6
which would result in the decrease of ΦF’s
.
Figure 9 also
shows that increasing spacer length could lead to more
pronounced reduction of ΦF’s for the samples in SmA phase
compared to that in Col
phase. This observation was in
H
accordance with the space length dependence of T (see Table
g
1). This meant that the increase of spacer length could
effectively make the sample to be soft and thus lose the
restriction of TPE motion.
CONCLUSIONS
■
In summary, we successfully synthesized a series of novel high
efficiency luminescent liquid crystalline polymers (Pms) based
on AIE luminogens and the “Jacketing” effect via radical
polymerization. Although all monomers and polymers showed
typical AIE behavior and solid-state emission, their luminescent
behavior and phase behavior were quite dependent on their
structures. Because of the existence of the “Jacketing” effect, all
polymers not only showed obvious luminescent behavior in LC
state, but also their luminescence efficiency significantly
decreased with increasing spacer length (their solid-state
quantum yields from 52% to 18%). Meanwhile, the alkyl
spacer length also impacted their phase behavior and phase
structure. With the increase of the alkyl spacer length, the glass
In addition to the typical AIE behavior of the solution, all
solid samples of Mms and Pms obtained from solution casting
showed clearly luminescent behavior. For the monomers, the
quantum yields (Φ ) measured were 5.0%, 3.0%, 2.8%, 2.6%,
F’s
2
.5%, and 2.1% determined by the integrating sphere.
Compared with the typical TPE molecule, the ΦF’s of the
monomers were very low, which might be attributed to the
amorphous state. As shown in Figure 9, the values of Φ
F’s
measured were 51.9%, 41.3%, 31.7%, 27.1%, 20.0%, and 18.1%
transition temperature (T ) gradually decreased, and their
g
H
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phase structure changed from smectic A phase (Pms, m = 2, 4,
Aggregation-Induced Emission Luminogen. Adv. Opt. Mater. 2016, 4,
5
(
34−539.
6
) to Col phase (Pms, m = 8, 10, 12). The results imply that
H
9) Hayasaka, H.; Tamura, K.; Akagi, K. Dynamic switching of
adjusting the alkyl spacers can be an effective way to control the
supramolecular structures and the photophysical properties of
the high efficiency luminescent liquid crystalline polymers with
the “Jacketing” effect, which provides a new method to fabricate
promising luminescent material.
linearly polarized emission in liquid-crystallinity-embedded photo-
responsive conjugated polymers. Macromolecules 2008, 41, 2341−
2
346.
(10) Seo, J.; Kim, S.; Gihm, S. H.; Park, C. R.; Park, S. Y. Highly
fluorescent columnar liquid crystals with elliptical molecular shape:
oblique molecular stacking and excited-state intramolecular proton-
transfer fluorescence. J. Mater. Chem. 2007, 17, 5052−5057.
(11) Vijayaraghavan, R. K.; Abraham, S.; Akiyama, H.; Furumi, S.;
Tamaoki, N.; Das, S. Photoresponsive Glass-Forming Butadiene-Based
Chiral Liquid Crystals with Circularly Polarized Photoluminescence.
Adv. Funct. Mater. 2008, 18, 2510−2517.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.macro-
mol.7b01605.
■
*
S
(
12) Whitehead, K.; Grell, M.; Bradley, D.; Inbasekaran, M.; Woo, E.
Polarized emission from liquid crystal polymers. Synth. Met. 2000, 111-
12, 181−185.
(13) Belletet
Experimental details; Figures S1−S7 (PDF)
1
AUTHOR INFORMATION
Corresponding Authors
E-mail: xhl20040731@163.com (H.L.X.).
E-mail: zqyu@szu.edu.cn (Z.Q.Y.).
̂
e, M.; Bouchard, J.; Leclerc, M.; Durocher, G.
■
Photophysics and solvent-induced aggregation of 2, 7-carbazole-
based conjugated polymers. Macromolecules 2005, 38, 880−887.
*
(14) Borisov, S. M.; Wolfbeis, O. S. Optical biosensors. Chem. Rev.
*
2
(
008, 108, 423−461.
15) Domaille, D. W.; Que, E. L.; Chang, C. J. Synthetic fluorescent
sensors for studying the cell biology of metals. Nat. Chem. Biol. 2008,
, 168−175.
16) Giepmans, B. N.; Adams, S. R.; Ellisman, M. H.; Tsien, R. Y.
ORCID
Zhen-Qiang Yu: 0000-0002-0862-9415
Er-Qiang Chen: 0000-0002-0408-5326
He-Lou Xie: 0000-0003-4103-2634
4
(
The fluorescent toolbox for assessing protein location and function.
Notes
Science 2006, 312, 217−224.
The authors declare no competing financial interest.
(17) Jakubiak, R.; Collison, C. J.; Wan, W. C.; Rothberg, L. J.; Hsieh,
B. R. Aggregation quenching of luminescence in electroluminescent
ACKNOWLEDGMENTS
This work is financially supported by the National Natural
Science Foundation of China (21374092, 21674088, and
1674065), the Nature Science Foundation of Hunan Province
conjugated polymers. J. Phys. Chem. A 1999, 103, 2394−2398.
■
(18) Lemmer, U.; Heun, S.; Mahrt, R.; Scherf, U.; Hopmeier, M.;
Siegner, U.; Go
in conjugated polymers. Chem. Phys. Lett. 1995, 240, 373−378.
19) Thomas, S. W.; Joly, G. D.; Swager, T. M. Chemical sensors
based on amplifying fluorescent conjugated polymers. Chem. Rev.
007, 107, 1339−1386.
20) Valeur, B.; Berberan-Santos, M. N. Molecular Fluorescence:
̈
̈ ̈
bel, E.; Mullen, K.; Bassler, H. Aggregate fluorescence
2
(
(
2016JJ2127), State Key Laboratory for Modification of
Chemical Fibers and Polymer Materials (LK1608), and
Hunan 2011 Collaborative Innovation Center of Chemical
Engineering & Technology with Environmental Benignity and
Effective Resource Utilization.
2
(
Principles and Applications; John Wiley & Sons: 2012.
(21) Sapsford, K. E.; Berti, L.; Medintz, I. L. Molecular fluorescence:
principles and applications. Angew. Chem., Int. Ed. 2006, 45, 4562−
4589.
REFERENCES
■
(22) Tsujimoto, H.; Ha, D. G.; Markopoulos, G.; Chae, H. S.; Baldo,
(
1) Grell, M.; Bradley, D. D. Polarized luminescence from oriented
molecular materials. Adv. Mater. 1999, 11, 895−905.
2) Hayasaka, H.; Miyashita, T.; Tamura, K.; Akagi, K. Helically π-
Stacked Conjugated Polymers Bearing Photoresponsive and Chiral
Moieties in Side Chains: Reversible Photoisomerization-Enforced
Switching Between Emission and Quenching of Circularly Polarized
Fluorescence. Adv. Funct. Mater. 2010, 20, 1243−1250.
3) Jeong, Y. S.; Akagi, K. Liquid crystalline PEDOT derivatives
exhibiting reversible anisotropic electrochromism and linearly and
M. A.; Swager, T. M. Thermally Activated Delayed Fluorescence and
Aggregation InducedEmission with Through-Space Charge Transfer. J.
Am. Chem. Soc. 2017, 139, 4894−4900.
(
(23) Ren, Y.; Dong, Y.; Lam, J. W.; Tang, B. Z.; Wong, K. S. Studies
on the aggregation-induced emission of silole film and crystal by time-
resolved fluorescence technique. Chem. Phys. Lett. 2005, 402, 468−
4
73.
(
(24) Luo, J. D.; Xie, Z. L.; Lam, J. W. Y.; Cheng, L.; Chen, H. Y.; Qiu,
C. F.; Kwok, H. S.; Zhan, X. W.; Liu, Y. Q.; Zhu, D. B.; Tang, B. Z.
Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole.
Chem. Commun. 2001, 18, 1740−1741.
circularly polarized dichroism. J. Mater. Chem. 2011, 21, 10472−
1
0481.
(
4) San Jose, B. A.; Matsushita, S.; Moroishi, Y.; Akagi, K.
Disubstituted liquid crystalline polyacetylene derivatives that exhibit
linearly polarized blue and green emissions. Macromolecules 2011, 44,
(25) Chen, Z. H.; Bouffard, J.; Kooi, S. E.; Swager, T. M. Highly
Emissive Iptycene-Fluorene Conjugated Copolymers: Synthesis and
Photophysical Properties. Macromolecules 2008, 41, 6672−6676.
(26) Dong, H.; Luo, M.; Wang, S.; Ma, X. Synthesis and properties of
tetraphenylethylene derivatived diarylethene with photochromism and
aggregation-induced emission. Dyes Pigm. 2017, 139, 118−128.
(27) Du, X.; Qi, J.; Zhang, Z.; Ma, D.; Wang, Z. Y. Efficient non-
doped near infrared organic light-emitting devices based on
fluorophores with aggregation-induced emission enhancement. Chem.
Mater. 2012, 24, 2178−2185.
(28) Deans, R.; Kim, J.; Machacek, M. R.; Swager, T. M. A Poly(p-
phenyleneethynylene) with a Highly Emissive Aggregated Phase. J.
Am. Chem. Soc. 2000, 122, 8565−8566.
(29) Kim, H. Ju.; Whang, D. R.; Gierschner, J.; Lee, C. H.; Park, S. Y.
High-Contrast Red−Green−Blue Tricolor Fluorescence Switching in
6
(
288−6302.
5) Schadt, M. Linear and non-linear liquid crystal materials, electro-
optical effects and surface interactions. Their application in present
and future devices. Liq. Cryst. 1993, 14, 73−104.
(
6) Sun, Q.; Park, K.; Dai, L. Liquid crystalline polymers for efficient
bilayer-bulk-heterojunction solar cells. J. Phys. Chem. C 2009, 113,
892−7897.
7) Conger, B. M.; Mastrangelo, J. C.; Chen, S. H. Fluorescence
7
(
behavior of low molar mass and polymer liquid crystals in ordered
solid films. Macromolecules 1997, 30, 4049−4055.
(
8) Zhao, D. Y.; He, H. X.; Gu, X. G.; Guo, L.; Wong, K. S.; Lam, J.
W. Y.; Tang, B. Z. Circularly Polarized Luminescence and a Reflective
Photoluminescent Chiral Nematic Liquid Crystal Display Based on an
I
DOI: 10.1021/acs.macromol.7b01605
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
Bicomponent Molecular Film. Angew. Chem., Int. Ed. 2015, 54, 4330−
chain liquid crystalline polytriazoles with aggregation-induced emission
characteristics. Macromolecules 2011, 44, 9618−9628.
(50) Kim, J. H.; Cho, S.; Cho, B. K. An Unusual Stacking
Transformation in Liquid-Crystalline Columnar Assemblies of Clicked
Molecular Propellers with Tunable Light Emissions. Chem. - Eur. J.
2014, 20, 12734−12739.
(51) Zhao, D.; Fan, F.; Cheng, J.; Zhang, Y.; Wong, K. S.; Chigrinov,
V. G.; Kwok, H. S.; Guo, L.; Tang, B. Z. Light-Emitting Liquid Crystal
Displays Based on an Aggregation-Induced Emission Luminogen. Adv.
Opt. Mater. 2015, 3, 199−202.
4
333.
(
30) Kwok, R. T.; Leung, C. W.; Lam, J. W.; Tang, B. Z. Biosensing
by luminogens with aggregation-induced emission characteristics.
Chem. Soc. Rev. 2015, 44, 4228−4238.
(
31) Mei, J.; Leung, N. L.; Kwok, R. T.; Lam, J. W.; Tang, B. Z.
Aggregation-induced emission: together we shine, united we soar.
Chem. Rev. 2015, 115, 11718−11940.
(
32) Xu, S.; Liu, T.; Mu, Y.; Wang, Y. F.; Chi, Z.; Lo, C. C.; Liu, S.;
Zhang, Y.; Lien, A.; Xu, J. An Organic Molecule with Asymmetric
Structure Exhibiting Aggregation-Induced Emission, Delayed Fluo-
rescence, and Mechanoluminescence. Angew. Chem., Int. Ed. 2015, 54,
(52) Wang, S. J.; Zhao, R. Y.; Yang, S.; Yu, Z. Q.; Chen, E. Q. A
complex of poly(4-vinylpyridine) and tolane based hemi-phasmid
benzoic acid: towards luminescent supramolecular side-chain liquid
crystalline polymers. Chem. Commun. 2014, 50, 8378−8381.
(53) Jing, H.; Lu, L.; Feng, Y. K.; Zheng, J. F.; Deng, L. D.; Chen, E.
Q.; Ren, X. K. Aggregation-Induced Emission, and Liquid Crystalline
Structure of Tetraphenylethylene−Surfactant Complex via Ionic Self-
Assembly. J. Phys. Chem. C 2016, 120, 27577−27586.
8
(
74−879.
33) Kwon, O. K.; Park, J. H.; Kim, D. W.; Park, S. K.; Park, S. Y.
High Contrast Fluorescence Patterning in Cyanostilbene-Based
Crystalline Thin Films: Crystallization-Induced Mass Flow Via a
Photo-Triggered Phase Transition. Adv. Mater. 2015, 27, 1951−1956.
(
34) An, B. K.; Kwon, S.-K.; Jung, S. D.; Park, S. Y. Enhanced
(
54) Hu, R.; Leung, N. L.; Tang, B. Z. AIE macromolecules:
syntheses, structures and functionalities. Chem. Soc. Rev. 2014, 43,
494−4562.
55) Beneduci, A.; Cospito, S.; La Deda, M.; Veltri, L.; Chidichimo,
Emission and Its Switching in Fluorescent Organic Nanoparticles. J.
Am. Chem. Soc. 2002, 124, 14410−14415.
4
(
(
35) Hong, Y.; Lam, J. W.; Tang, B. Z. Aggregation-induced
emission: phenomenon, mechanism and applications. Chem. Commun.
009, 29, 4332−4353.
36) Hong, Y.; Lam, J. W.; Tang, B. Z. Aggregation-induced
emission. Chem. Soc. Rev. 2011, 40, 5361−5388.
37) Liu, J.; Lam, J. W.; Tang, B. Z. Acetylenic polymers: syntheses,
structures, and functions. Chem. Rev. 2009, 109, 5799−5867.
38) Wang, M.; Zhang, G.; Zhang, D.; Zhu, D.; Tang, B. Z.
G. Electrofluorochromism in π-conjugated ionic liquid crystals. Nat.
Commun. 2014, DOI: 10.1038/ncomms4105.
2
(
(56) Fujisawa, K.; Okuda, Y.; Izumi, Y.; Nagamatsu, A.; Rokusha, Y.;
Sadaike, Y.; Tsutsumi, O. Reversible thermal-mode control of
luminescence from liquid-crystalline gold (I) complexes. J. Mater.
Chem. C 2014, 2, 3549−3555.
(
(
(57) Wang, Y. F.; Shi, J.; Chen, J.; Zhu, W. G.; Baranoff, E. Recent
luorescent bio/chemosensors based on silole and tetraphenylethene
luminogens with aggregation-induced emission feature. J. Mater. Chem.
progress in luminescent liquid crystal materials: design, properties and
application for linearly polarised emission. J. Mater. Chem. C 2015, 3,
2
(
010, 20, 1858−1867.
7
993−8005.
58) Zhou, Q. F.; Li, H. M.; Feng, X. D. Synthesis of liquid-crystalline
polyacrylates with laterally substituted mesogens. Macromolecules
987, 20, 233−234.
59) Liu, Y.; Zhang, D.; Wan, X. H.; Zhou, Q. F. Synthesis of a Novel
Mesogen-Jacketed Liquid Crystal Polymer” Based on Vinyltereph-
thatic Acid. Chin. J. Polym. Sci. 1998, 16, 283−283.
60) Chen, X. F.; Shen, Z. H.; Wan, X. H.; Fan, X. H.; Chen, E. Q.;
39) Zhao, Z.; Lam, J. W.; Tang, B. Z. Tetraphenylethene: a versatile
(
AIE building block for the construction of efficient luminescent
materials for organic light-emitting diodes. J. Mater. Chem. 2012, 22,
1
(
“
2
(
3726−23740.
40) Zhao, Z.; Lam, J. W. Y.; Zhong Tang, B. Aggregation-induced
emission of tetraarylethene luminogens. Curr. Org. Chem. 2010, 14,
109−2132.
41) Xu, Y.; Chen, L.; Guo, Z.; Nagai, A.; Jiang, D. Light-emitting
2
(
(
Ma, Y. G.; Zhou, Q. F. Mesogen-jacketed liquid crystalline polymers.
conjugated polymers with microporous network architecture:
interweaving scaffold promotes electronic conjugation, facilitates
exciton migration, and improves luminescence. J. Am. Chem. Soc.
Chem. Soc. Rev. 2010, 39, 3072−3101.
(61) Xie, H. L.; Jie, C. K.; Yu, Z. Q.; Liu, X. B.; Zhang, H. L.; Shen, Z.
H.; Chen, E. Q.; Zhou, Q. F. Design, synthesis, and characterization of
a combined main-chain/side-chain liquid crystalline polymer based on
mesogen-jacketed liquid crystal polymer via atom transfer radical
polymerization. J. Am. Chem. Soc. 2010, 132, 8071−8080.
2
(
011, 133, 17622−17625.
42) Krikorian, M.; Liu, S.; Swager, T. M. Columnar Liquid
Crystallinity and Mechanochromism in Cationic Platinum(II)
Complexes. J. Am. Chem. Soc. 2014, 136, 2952−2955.
(62) Ye, C.; Zhang, H. L.; Huang, Y.; Chen, E. Q.; Lu, Y.; Shen, D.;
(
43) O’Neill, M.; Kelly, S. M. Liquid crystals for charge transport,
Wan, X. H.; Shen, Z.; Cheng, S. Z.; Zhou, Q. F. Molecular weight
dependence of phase structures and transitions of mesogen-jacketed
liquid crystalline polymers based on 2-vinylterephthalic acids.
Macromolecules 2004, 37, 7188−7196.
luminescence, and photonics. Adv. Mater. 2003, 15, 1135−1146.
(
44) Park, J. W.; Nagano, S.; Yoon, S. J.; Dohi, T.; Seo, J. W.; Seki,
T.; Park, S. Y. High Contrast Fluorescence Patterning in
Cyanostilbene-Based Crystalline Thin Films: Crystallization-Induced
Mass Flow Via a Photo-Triggered Phase Transition. Adv. Mater. 2014,
(63) Zhu, Y. F.; Guan, X. L.; Shen, Z.; Fan, X. H.; Zhou, Q. F.
Competition and promotion between two different liquid-crystalline
building blocks: mesogen-jacketed liquid-crystalline polymers and
triphenylene discotic liquid crystals. Macromolecules 2012, 45, 3346−
2
(
6, 1354−1359.
45) Tanabe, K.; Suzui, Y.; Hasegawa, M.; Kato, T. Full-Color
Tunable Photoluminescent Ionic Liquid Crystals Based on Tripodal
Pyridinium, Pyrimidinium, and Quinolinium Salts. J. Am. Chem. Soc.
3
(
355.
64) Weng, L.; Yan, J. J.; Xie, H. L.; Zhong, G. Q.; Zhu, S. Q.; Zhang,
2
(
012, 134, 5652−5661.
H. L.; Chen, E. Q. Design, synthesis, and self-assembly manipulating of
polymerized ionic liquids contained imidazolium based on “Jacketing”
effect. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 1912−1923.
46) Sagara, Y.; Kato, T. Stimuli-Responsive Luminescent Liquid
Crystals: Change of Photoluminescent Colors Triggered by a Shear-
Induced Phase Transition. Angew. Chem. 2008, 120, 5253−5256.
(65) Yan, J. J.; Xie, H. L.; Weng, L.; Yang, S.; Zhang, H. L.
(
47) Sagara, Y.; Kato, T. Brightly Tricolored Mechanochromic
Manipulating ordered structure of ionic liquid crystalline polymers
Luminescence from a Single Luminophore Liquid Crystal: Reversible
through tuning the alkyl spacer length. Polymer 2014, 55, 6504−6512.
Writing and Erasing of Images. Angew. Chem. 2011, 123, 9294−9298.
(66) Fan, X.; Sun, J. L.; Wang, Z. Z.; Wang, P.; Dong, Y. Q.; Hu, R.
(
48) Yuan, W. Z.; Yu, Z. Q.; Lu, P.; Deng, C.; Lam, J. W.; Wang, Z.;
R.; Tang, B. Z.; Zou, D. C. Photoluminescence and electro-
luminescence of hexaphenylsilole are enhanced by pressurization in
the solid state. Chem. Commun. 2008, 26, 2989−2991.
Chen, E. Q.; Ma, Y.; Tang, B. Z. High efficiency luminescent liquid
crystal: aggregation-induced emission strategy and biaxially oriented
mesomorphic structure. J. Mater. Chem. 2012, 22, 3323−3326.
(
49) Yuan, W. Z.; Yu, Z. Q.; Tang, Y.; Lam, J. W.; Xie, N.; Lu, P.;
Chen, E. Q.; Tang, B. Z. High solid-state efficiency fluorescent main
J
DOI: 10.1021/acs.macromol.7b01605
Macromolecules XXXX, XXX, XXX−XXX