Synthesis and characterization of polypropyleneimine dendrimers having peripheral mesogenic groups: Homeotropic orientation and mesogen structure

Article abstract of DOI:10.1080/15421406.2012.762501

In order to estimate the effectiveness of mesogenic structure on the spontaneous homeotropic orientation of side-chain type liquid crystalline dendrimers, five mesogens, 4′-methoxybiphenyl (PPO1), 4-methoxyphenyl benzoate (BPO1), trans-4-(4-pentylcyclohex

Full text of DOI:10.1080/15421406.2012.762501

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Synthesis and Characterization of
Polypropyleneimine Dendrimers
Having Peripheral Mesogenic Groups:
Homeotropic Orientation and Mesogen
Structure
O. Haba a , D. Hiratsuka a , T. Shiraiwa a , T. Koda a , K. Yonetake a
Y. Momoi b & K. Furuta b
,
a Graduate School of Science and Engineering, Yamagata University
Yonezawa , Yamagata , Japan
b LG Display Japan Laboratory, Glass Cube Shinagawa , Shinagawa-
ku , Tokyo , Japan
Published online: 02 Apr 2013.
To cite this article: O. Haba , D. Hiratsuka , T. Shiraiwa , T. Koda , K. Yonetake , Y. Momoi & K. Furuta
(2013) Synthesis and Characterization of Polypropyleneimine Dendrimers Having Peripheral Mesogenic
Groups: Homeotropic Orientation and Mesogen Structure, Molecular Crystals and Liquid Crystals,
574:1, 84-95, DOI: 10.1080/15421406.2012.762501
To link to this article: http://dx.doi.org/10.1080/15421406.2012.762501
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Mol. Cryst. Liq. Cryst., Vol. 574: pp. 84–95, 2013
Copyright © Taylor & Francis Group, LLC
ISSN: 1542-1406 print/1563-5287 online
DOI: 10.1080/15421406.2012.762501
Synthesis and Characterization of
Polypropyleneimine Dendrimers Having Peripheral
Mesogenic Groups: Homeotropic Orientation
and Mesogen Structure
O. HABA,1,∗ D. HIRATSUKA,1 T. SHIRAIWA,1 T. KODA,1
K. YONETAKE,1 Y. MOMOI,2 AND K. FURUTA2
1Graduate School of Science and Engineering, Yamagata University Yonezawa,
Yamagata, Japan
2LG Display Japan Laboratory, Glass Cube Shinagawa, Shinagawa-ku,
Tokyo, Japan
In order to estimate the effectiveness of mesogenic structure on the spontaneous
homeotropic orientation of side-chain type liquid crystalline dendrimers, five meso-
gens, 4ꢀ-methoxybiphenyl (PPO1), 4-methoxyphenyl benzoate (BPO1), trans-4-(4-
pentylcyclohexyl)phenyl (PC5), 4ꢀ-fluorobiphenyl (PPF), and 3ꢀ,4ꢀ,5ꢀ-trifluorobiphenyl
(PPF3), were introduced to the terminal amino groups of a second-generation polypropy-
leneimine dendrimer. Among them, the PC5 mesogen exhibited superior homeotropic
orientation during the slow cooling process from the isotropic melt. Using the PC5
mesogen, the effect of the spacer length (n) was also examined. Homeotropic orienta-
tion was observed only for n = 3 and 6, which exhibited a stable smectic A phase in a
wide temperature range.
Keywords DSC; homeotropic orientation; polypropyleneimine dendrimer; POM;
smectic phase; XRD
Introduction
Dendrimer-based liquid crystalline (LC) materials are seeking great attention due to their
unique structures and properties. Numerous LC dendrimers, including side chain, main
chain, and dendron types, have been reported [1–5]. Side-chain LC dendrimers consisting of
peripheral mesogenic groups with dendritic cores, including polyamidoamine, polypropy-
leneimine, polycarbosilane, polysiloxane, and so on, have been reported. The relationship
between their liquid crystallinity and the structure of LC dendrimers, such as generation,
mesogenic unit, length of spacer between the dendritic core and the mesogenic units, has
been also studied. According to the reports, side-chain LC dendrimers tend to form smectic
or discotic columnar phases depending on the mesogenic structure. Mesogens having one
terminal alkyl group tend to cause the smectic phase, and those with two or more alkyl
groups favor the discotic phase.
∗Address correspondence to Osamu Haba, Graduate School of Science and Engineering, Ya-
magata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan. Tel.: +81-238-26-3091.
E-mail: haba@yz.yamagata-u.ac.jp
84

Homeotropic Orientation of LC Dendrimers
85
We have also reported syntheses and characterizations of poly(amidoamine)-based and
polypropyleneimine-based side-chain LC dendrimers possessing rigid 4ꢀ-cyanobiphenyl
[6–8], 2,3-dicyanophenyl [9], or 2,3-difluorophenyl [10] mesogens. Among them, the
polypropyleneimine dendrimer with mesogenic groups coupled through ester linkage ex-
hibited a thermotropic LC nature showing the smectic A phase. Furthermore, spontaneous
homeotropic orientation took place in LC dendrimers with a second-generation scaffold,
when it was slowly cooled or kept in the smectic A phase on an untreated glass surface
[8–10]. Such homeotropic orientation has been observed in some LC dendrimers having
cholesteryl mesogenic groups [11–13] or dodecyloxy groups [12,14] on a mica, carbon, or
glass surface, but has not been reported for other numerous dendrimers. Thus, there are still
some questions as to why spontaneous homeotropic orientation occurred, and what type of
LC dendrimers aligns homeotropically on a native glass surface.
For the spontaneous homeotropic orientation of LC dendrimers between two glass
substrates, we have assumed that the dendrimers form a cylindrical shape by gathering
together the mesogenic groups in their smectic phase [10]. The tail of the mesogenic
groups in such structural contact with the glass surface, and therefore the affinity of the
mesogenic groups to the glass surface, may play an important role for such an orientation.
In this paper, we prepared and characterized second-generation polypropyleneimine-based
LC dendrimers having five different types of mesogens with C6 spacers, and investigate
the relationship between the mesogenic structure and the homeotropicity. In addition, the
effect of the spacer length was also examined.
Results and Discussion
Synthesis and Characterization of LC Dendrimers
Our previous dendrimers possess cyano and butoxy groups in the termini, and these seem
to be sufficient for homeotropic orientation. In order to estimate the affinity, we selected
Table 1. Abbreviations for the mesogenic units
X
Structure
PPO1
OCH3
BPO1
PC5
O
O
OCH3
C5H11
PPF
F
PPF3
F
F
F

86
O. Haba et al.
five mesogens, 4ꢀ-methoxybiphenyl (PPO1), 4-methoxyphenyl benzoate (BPO1), trans-4-
(4-pentylcyclohexyl)phenyl (PC5), 4ꢀ-fluorobiphenyl (PPF), and 3ꢀ,4ꢀ,5ꢀ-trifluorobiphenyl
(PPF3) shown in Table 1, considering their availability. PPO1 and BPO1 have shorter
alkyl groups than the butoxy group, whereas the 4-pentylcyclohexyl group of PC5 can be
regarded as a longer alkyl chain. PPF and PPF3 have one and three hydrophobic fluorine
atoms, respectively, and many F atoms should cause much repulsion toward the glass
surface.
We prepared eight second-generation polypropyleneimine dendrimers peripherally
modified with the mesogenic groups as shown in Table 1. We named the dendrimers
“D-nX,” where n is the number of carbons in the spacer chain, and X stands for the
mesogenic groups. D-nXs were prepared by our previously reported procedure, start-
ing from the corresponding phenols, as shown in Scheme 1. The phenols react with ω-
bromoalkanols to give alcohols (HO-nX) having the mesogen, which was converted to
an acrylate (Acr-nX). The introduction of Acr-nX to the commercial second-generation
polypropyleneimine dendrimer (DAB-Am-8) was achieved by Michael addition of the
peripheral amino groups to the acrylate. The reaction was conducted by heating the DAB-
Am-8 and Acr-nX at 50◦C in tetrahydrofuran (THF) for 1 week monitoring a disappearance
of the primary and secondary amino groups due to incomplete additions by 1H NMR spec-
troscopy. The reaction mixture was poured into methanol and the precipitate was filtered
and washed with methanol several times. The target dendrimers were obtained as a white
or pale yellow sticky solid except for D-6P2F3, which was colorless viscous oil at room
temperature.
Scheme 1. Preparation of D-nXsa). a) Conditions: (i) HO—(CH2)n—Br, K2CO3, 2-butanone, reflux,
60 h; (ii) CH2=CH—COCl, Et3N, THF, 60◦C, RT, 24 h; (iii) THF, 60◦C, 7 days.

Homeotropic Orientation of LC Dendrimers
87
Figure 1. 1H NMR spectra of D-6PC5 measured in CDCl3 at room temperature.
The infrared (IR) spectra of all dendrimers showed characteristic ester carbonyl bands
at 1730 cm–1, and no peaks at 3290–3300 cm–1 due to the presence of primary amino
groups. Figure 1 shows the 1H NMR spectrum for D-6PC5, which has 16 cyclohexylphenyl
units at the chain ends. Some distinct features are apparent. All protons in the structure
were identified. All assignments are inset in Fig. 1. Other dendrimers also showed similar
1H NMR spectra.
The molecular weights of D-6Xs were estimated by matrix-assisted laser desorption
ionization time-of-flight (MALDI-TOF) mass spectrometry. The dendrimers show one
signal that is clearly due to the formation of the desired dendrimers with 16 mesogens. The
obtained m/z values of the signal corresponded to the calculated value. The results are also
listed in Table 2. These results clearly indicate the formation of the desired dendrimers
modified with terminal mesogenic groups.
Phase Transition of D-6Xs
Figure 2 shows differential scanning calorimetry (DSC) traces of D-6Xs, having C6 spacers,
in the second cooling process. The dendrimers showed exothermic peaks except for D-
6PPF3, which is viscous oil at room temperature. D-6PPO1 and D-6PC5 showed two
Table 2. Results of MALDI-TOF MS measurementsa
Molecular weight (M+Na+) (Da)
LC dendrimer
Theoretical
Observed
D-6PC5
D-6PPO1
D-6PBO1
D-6PPF
7205.57
6466.74
7170.57
6274.42
7209.03
6468.07
7172.48
6273.65
—
D-6PPF3
aMeasured using DHBA as the matrix.

88
O. Haba et al.
Figure 2. DSC thermograms of D-6Xs in the second cooling cycle. Cooling rate=10◦C·min–1.
distinct peaks, which indicate they form two kinds of mesophase. The optical textures of
D-6Xs were observed under polarizing optical microscope (POM) with crossed polarizers
to explore the LC phases. D-6PPF3 showed a dark field within the whole temperature
range due to the isotropic phase, and did not form a LC phase. Similar dark isotropic
melts were observed at 100◦C for the other D-6Xs, and therefore phase transition at a
higher temperature is due to a clearing point. Figure 3 shows typical optical textures at
temperatures below the clearing point. D-6PPO1 shows a schlieren texture, D-6PBO1 and
D-6PC5 a focalconic fan texture, and D-6PPF a tiny schlieren texture. Thus, all samples
exhibit an LC nature. X-ray diffraction (XRD) measurements were carried out to determine
Figure 3. Polarizing optical micrographs of D-6Xs.

Homeotropic Orientation of LC Dendrimers
89
Figure 4. X-ray diffraction patterns of D-6Xs.
the liquid crystal phases. The XRD patterns and intensity curves are shown in Figs. 4 and 5,
respectively. The XRD patterns of all samples show Debye–Sherrer rings at the small-
angle area. The reflections are due to smectic layer structure. D-6PPO1 and D-6PPF show
comparatively sharp rings at the wide-angle area. The three reflections at the wide-angle
area could be assigned to (110), (200), and (210) reflections of an orthorhombic packing
mode. Thus, their LC phases are smectic E (SmE). The lattice parameters, a and b, of
D-6PPO1 and D-6PPF were estimated from the d values of the three reflections as shown
in Table 3. In contrast, a diffuse halo at the wide-angle area was observed in D-6PBO1
and D-6PC5. The diffuse reflection at the wide-angle area was obtained at approximately
0.45 nm, which corresponds to the lateral distance between the mesogens. These results
confirmed that their LC phases were smectic A (SmA).
Figure 6 shows POM images of the D-6Xs during slow cooling (cooling rate =
1.0◦C·min–1) from isotropic melt on the native glass surface. The textures of D-6PPO1 and
D-6BPO1 below the clearing point were unchanged until the temperature reached Tg. On
the other hand, the focalconic fan texture of D-6PC5 disappeared and the area of dark field
gradually expanded. The typical cross isogyre was observed in the dark field by conoscopic
Table 3. Lattice parameters a and b of SmE phase for D-6PPO1 and D-6PPF
Lattice parameter (nm)
Sample
a
b
D-6PPO1
D-6PPF
0.74
0.78
0.55
0.53

90
O. Haba et al.
Figure 5. X-ray diffraction intensity curves of D-6Xs.
observation under a polarizing optical microscope. This suggests spontaneous homeotropic
orientation on the native glass surface.
Changes in Phase Transition of D-nPC5s With Spacer Length
As mentioned above, the PC5 mesogen showed superior homeotropicity compared to the
other four mesogens. Then we prepared D-3PC5 and D-12PC5, which have C3 and C12
spacers, respectively, with the PC5 mesogen, in order to examine the effect of spacer length
on the homeotropicity. Table 4 summarizes the phase transition behavior of the D-nPC5s.
D-3PC5 and D-12PC5 showed two-phase transition temperatures above Tg in their DSC
measurements as well as D-6PC5. From POM observations and XRD measurements, they
exhibited smectic B and smectic A phases at the lower and the higher temperature region,
respectively, as shown in D-6PC5. Figure 7 shows the effect of the spacer length (n) of
D-nPC5 on the phase transition temperature. It was clearly seen that the longer alkyl spacer
makes the SmB phase thermodynamically stable.

Homeotropic Orientation of LC Dendrimers
91
Figure 6. Polarizing optical micrographs of D-6Xs under cooling at 1◦C×min–1 from melt.
Figure 8 shows the optical textures of D-nPC5s (n = 3 and 12) slowly cooled at
1◦C·min–1 from isotropic melt on the native glass surface. Similar to D-6PC5, the optical
texture of D-3PC5 disappeared and the area of dark field gradually expanded with cooling.
D-3PC5 also showed the typical conoscopic pattern, which suggests that D-3PC5 can
spontaneously aligned homeotropically on the native glass surface. On the other hand,
when D-12PC5 was cooled slowly, the fan shape texture did not disappear until reaching
the glass transition temperature. The temperature range showing the smectic A phase was
much narrower for D-12PC5 compared to D-3PC5 and D-6PC5. Therefore, spontaneous
homeotropic orientation, observed for D-3PC5 and D-6PC5 should occur in their smectic
Table 4. Phase transition behavior of D-nPC5sa
Phase transition temperature (◦C) (ꢀH (J g–1)
Heating
Cooling
D-3PC5
D-6PC5
D-12PC5
G –8.1 SB 16.9 (0.79) SA
77.9 (9.24) I
G –15.2 SB 20.2 (1.18) SA
73 (9.70) I
G 8.6 SB 74.2 (11.2) SA
81.8 (9.60) I
I 74.3 (8.49) SA 15.5 (0.64)
SB –14.1 G
I 69.4 (10.0) SA 16.7 (1.40)
SB –20.6 G
I 79.8 (9.6) SA 72.6 (9.80)
SB 5.2 G
aG: glassy, SB: smectic B, SA: smectic A, I: isotropic.

92
O. Haba et al.
Figure 7. Plots of the phase transition temperatures of D-nPC5s versus the number of carbon atoms
in the spacer (n), measured in second cooling scan.
A phase, and such rearrangement of the mesogenic units hardly occurs in the higher order
smectic B phase.
Effect of the Mesogen Structure on the Homeotropic Orientation
From the results about D-nPC5s, it is suggested that the homeotropic orientation should
occur in the smectic A phase. This is supported by the results that PPO1 and PPF mesogens,
which exhibited smectic B phase, also did not show the homeotropic orientation. However,
the BPO1 mesogen did not show homeotropic orientation although that exhibited stable
smectic A phase as well as PC5. Thus, the alkyl chain in termini of PC5 might be effective
for the homeotropic orientation. This should be supported by the results in our previous
works (butoxy termini) and in literature (dodecyloxy termini). Unfortunately, the affinity
of mesogen toward the glass surface still remains unclear, because the both fluorinated
mesogens, PPF and PPF3, did not orient homeotropically. Therefore, further works should
Figure 8. Polarizing optical micrographs of D-nPC5s under cooling at 1◦C×min–1 from melt.

Homeotropic Orientation of LC Dendrimers
93
be necessary to clear the effect of polar terminal groups and length of the alkyl termini in
the future.
Summary
As described above, five mosogens were introduced to second-generation polypropy-
leneimine dendrimers to examine the effectiveness of the mesogenic structure on the
spontaneous homeotropic orientation of LC dendrimers on a native glass surface. Among
them, the PC5 mesogen exhibited superior homeotropic orientation during the slow cooling
process from isotropic melt. Using the PC5 mesogen, the effect of the spacer length (n)
was also examined. The LC dendrimers with n = 3 and 6 exhibited a stable smectic A
phase in a wide temperature range, whereas the smectic B phase was stable with n = 12.
Homeotropic orientation was not observed with n = 12, and therefore the stable smectic A
phase seems to be necessary during the slow cooling process in order to homeotropically
rearrange the mesogenic units.
Experimental Section
Measurements
The IR spectra were recorded on a HORIBA FT-210 spectrometer, and the NMR spectra
on a JEOL JNM-ECX 400 (400 MHz for 1H and 100 MHz for 13C) spectrometer. MALDI-
TOF ultraviolet mass spectroscopy was performed on a PE Biosystems Voyager-DE Pro
spectrometer using 2,4-dihydroxybenzoic acid (DHBA) as the matrix. DSC was recorded
on a TA instrument Q200 instrument at a heating/cooling rate of 10◦C·min-1 in nitrogen.
Optical textures of the samples were examined using a POM (Olympus Co. Ltd.) equipped
with a hot stage (Linkam Co., TH-600RMS) under nitrogen. XRD experiments were carried
out on a RAD-rA diffractometer (Rigaku Denki Co. Ltd.) equipped with a heating device.
Nickel-filtered CuKα radiation was employed. XRD traces were recorded by a scintillation
counter system with a 1.0-mm diameter pinhole collimator and 1◦ × 1◦ receiving slit.
Diffractometry was performed in transmission. The XRD traces were obtained by a step-
scanning method: step width and fixed time were programmed for steps of 0.05◦ every 10 s.
XRD photographs were taken with a flat Laue camera with a 0.5-mm diameter pinhole
collimator.
Materials
4-(trans-4-Pentylcyclohexyl)phenol (PC5) (Kanto Chemicals), 6-bromohexanol (TCI), 12-
bromodecanol (TCI), 3-bromopropanol (TCI), acryloyl chloride (Ardrich), and second-
generation polypropyleneimine dendrimer (DAB-Am-8, Ardrich) were purchased and
used as received. 6-[4-(4-Methoxyphenyl)phenyloxy]hexyl acrylate (Acr-6PPO1), 6-[4-
(methoxyphenyloxycarbonyl-phenyl]hexyl acrylate (Acr-6BPO1), 6-[4-(4-fluorophenyl)
phenyloxy]hexyl acrylate (Acr-6PPF), and 6-[4-(3,4,5-trifluorophenyl)phenyloxy]hexyl
acrylate (Acr-6PPF3) were obtained from Koyo Chemical Industry Inc. 6-[4-(trans-4-
Pentylcyclohexyl)phenoxy]alkyl acrylates (Acr-nPC5) were prepared by a previously re-
ported method [15]. THF was distilled from sodium–benzophenone ketyl just before use.
Unless otherwise noted, the other chemicals were commercially available and used without
further purification.

94
O. Haba et al.
General Procedure for Peripherally Modified Propyleneimine Dendrimers (D-nX)
A solution of DAB-Am-8 dendrimer, Acr-nX, in THF (2.0 mol×L–1 for Acr-nX) was stirred
at 50◦C for 72 h under an N2 atmosphere. The solution was concentrated under reduced
pressure. The residue was dissolved to a minimal volume of CHCl3 and the resulting
solution was poured into an excess of CH3OH. The precipitated sticky solid or viscous oil
were separated from the solvents by decantation. This operation was repeated further two
times and dried in vacuo to give D-nX.
D-6PPO1 was prepared from 0.33 g of DAB-Am-8 dendrimer (0.43 mmol) and 7.0 g
of Acr-6PPO1 (19 mmol). Yield: 1.3 g (47%). 1H NMR (CDCl3): δ (ppm) = 7.43 (q, J =
6.4 Hz, 64H, ArH), 6.89 (t, J = 11 Hz, 64H, ArCH), 4.03 (t, J = 6.4 Hz, 32H, OCH2), 3.91
(t, J = 6.9 Hz, 32H, PhOCH2), 3.79 (s, 48H, OCH3), 2.75 (t, J = 7.3 Hz, 32H, N−CH2),
2.41 (t, J = 7.3 Hz, 84H, N−CH2 and CH2C=O), 1.85–1.29 (m, 284H, CH2).
D-6BPO1 was prepared from 0.28 g of DAB-Am-8 dendrimer (0.31 mmol) and 6.0 g
of Acr-6BPO1 (15 mmol). Yield: 1.7 g (76%). 1H NMR (CDCl3): δ (ppm) = 8.07 (d, J =
9.2 Hz, 32H, ArH), 7.08 (d, J = 9.2 Hz, 32H, ArH), 6.92 (t, J = 8.7 Hz, 64H, ArCH), 4.12
(t, J = 6.4 Hz, 32H, OCH2), 3.98 (t, J = 6.4 Hz, 32H, PhOCH2), 3.78 (s, 48H, OCH3),
2.74 (t, J = 7.3 Hz, 32H, N−CH2), 2.42 (t, J = 6.9 Hz, 84H, N−CH2 and CH2C=O),
1.91–1.31 (m, 284H, CH2).
D-6PPF was prepared from 0.33 g of DAB-Am-8 dendrimer (0.43 mmol) and 7.0 g
of Acr-6PPF (20 mmol). Yield: 1.9 g (72%). 1H NMR (CDCl3): δ (ppm) = 7.43 (m, 64H,
ArH), 7.05 (t, J = 8.7 Hz, 32H, ArH), 6.88 (d, J = 8.2 Hz, 32H, ArCH), 4.04 (t, J = 6.4 Hz,
32H, OCH2), 3.91 (t, J = 6.4 Hz, 32H, PhOCH2), 2.74 (t, J = 6.4 Hz, 32H, N−CH2), 2.39
(t, J = 6.9 Hz, 84H, N−CH2 and CH2C=O), 1.84–1.31 (m, 284H, CH2).
D-6PPF3 was prepared from 0.25 g of DAB-Am-8 dendrimer (0.32 mmol) and 6.0 g
of Acr-6PPF3 (15 mmol). Yield: 1.3 g (59%). 1H NMR (CDCl3): δ (ppm) = 7.37 (d, J =
7.8 Hz, 32H, ArH), 7.08 (t, J = 6.4 Hz, 32H, ArH), 6.89 (d, J = 7.7 Hz, 32H, ArCH), 4.06
(t, J = 6.4 Hz, 32H, OCH2), 3.94 (t, J = 5.5 Hz, 32H, PhOCH2), 2.74 (t, J = 6.4 Hz, 32H,
N−CH2), 2.41 (t, J = 6.8 Hz, 84H, N−CH2 and CH2C=O), 1.86–1.30 (m, 284H, CH2).
D-3PC5 was prepared from 0.44 g of DAB-Am-8 dendrimer (0.57 mmol) and 6.5 g of
Acr-3PC5 (18 mmol). Yield: 2.1 g (57%). 1H NMR (CDCl3): δ (ppm) = 7.08 (d, J = 8.6 Hz,
32H, Ar–H), 6.78 (d, J = 8.6 Hz, 32H, Ar–H), 4.21 (t, J = 6.3 Hz, 32H, CH2–OCO), 3.97
(t, J = 5.9 Hz, 32H, CH2–O–Ar), 2.74 (t, J = 6.8 Hz, 32H, CH2–COO), 2.30–2.50 (m,
100H, CH2–N and Ar–CH), 1.95–2.15 (m, 32H, O–CH2CH2CH2–O), 1.83 (d, J = 10.9 Hz,
64H, cyclohexyl CH2eq), 1.60–1.73 (br, 4H, N–CH2CH2CH2CH2–N), 1.47–1.60 (br, 16H,
cyclohexyl CH–CH2), 1.10–1.47 (m, 184H, alkyl CH2 and cyclohexyl CH2ax), 0.95–1.10
(m, 32H, CH2CH3), 0.89 (t, J = 7.3 Hz, 48H, CH3).
D-6PC5 was prepared from 0.48 g of DAB-Am-8 dendrimer (0.62 mmol) and 12 g of
Acr-6PC5 (30 mmol). Yield: 2.5 g (56%). 1H NMR (CDCl3): δ (ppm) = 7.08 (d, J = 8.6 Hz,
32H, Ar–H), 6.79 (d, J = 8.6 Hz, 32H, Ar–H), 4.04 (t, J = 6.8 Hz, 32H, CH2–OCO), 3.89
(t, J = 6.3 Hz, 32H, CH2–O–Ar), 2.76 (t, J = 7.3 Hz, 32H, CH2–COO), 2.30–2.50 (m,
100H, CH2–N and Ar–CH), 1.12–1.90 (m, 396H, alkyl CH and CH2), 0.94–1.10 (m, 32H,
CH2CH3), 0.89 (t, J = 7.3 Hz, 48H, CH3).
D-12PC5 was prepared from 0.26 g of DAB-Am-8 dendrimer (0.34 mmol) and 8.0 g
of Acr-12PC5 (17 mmol). Yield: 1.1 g (38%). 1H NMR (CDCl3): δ (ppm) = 7.09 (d, J =
8.6 Hz, 32H, Ar–H), 6.80 (d, J = 8.6 Hz, 32H, Ar–H), 4.03 (t, J = 6.8 Hz, 32H, CH2–OCO),
3.90 (t, J = 6.3 Hz, 32H, CH2–O–Ar), 2.76 (t, J = 7.2 Hz, 32H, CH2–COO), 2.30–2.50
(m, 100H, CH2–N and Ar–CH), 1.17–1.98 (m, 588H, alkyl CH and CH2), 0.94–1.10 (m,
32H, CH2CH3), 0.89 (t, J = 7.2 Hz, 48H, CH3).

Homeotropic Orientation of LC Dendrimers
95
References
[1] Donnio, B., Buathong, S., Bury, I., & Guillon, D. (2007). Chem. Soc. Rev., 36, 1495.
[2] Newkome, G. R., & Shreiner, C. D. (2008). Polymer, 49, 1.
[3] Saez, I. M., & Goodby, J. W. (2005). J. Mater. Chem., 15, 26.
[4] Barbera, J., Donnio, B., Gehringer, L., Guillon, D., Marcos, M., Omenat, A., & Serrano, J. L.
(2005). J. Mater. Chem., 15, 4093.
[5] Rosen, B. M., Wilson, C. J., Wilson, D. A., Peterca, M., Imam, M. R., & Percec, V. (2009).
Chem. Rev., 109, 6275.
[6] Suzuki, K., Haba, O., Nagahata, R., Yonetake, K., & Ueda, M. (1998). High Perform. Polym.,
10, 231.
[7] Yonetake, K., Suzuki, K., Morishita, T., Nagahata, R., & Ueda, M. (1998). High Perform.
Polym., 10, 373.
[8] Yonetake, K., Masuko, T., Morishita, T., Suzuki, K., Ueda, M., & Nagahata, R. (1999). Macro-
molecules, 32, 6578.
[9] Haba, O., Okuyama, K., & Yonetake, K. (2001). Mol. Cryst. Liq. Cryst., 364, 929.
[10] Haba, O., Okuyama, K. I., Osawa, H., & Yonetake, K. (2005). Liq. Cryst., 32, 633.
[11] Coen, M. C., Lorenz, K., Kressler, J., Frey, H., & Mulhaupt, R. (1996). Macromolecules, 29,
8069.
[12] Precup-Blaga, F. S., Schenning, A. P. H. J., & Meijer, E. W. (2003). Macromolecules, 36, 565.
[13] Dardel, B., Deschenaux, R., Even, M., & Serrano, E. (1999). Macromolecules, 32, 5193.
[14] Jung, H. T., Kim, S. O., Ko, Y. K., Yoon, D. K., Hudson, S. D., Percec, V., Holerca, M. N., Cho,
W. D., & Mosier, P. E. (2002). Macromolecules, 35, 3717.
[15] Sainath, A. V. S., Yonetake, K., Aita, T., Inoue, T., & Koyama, K. (2003). Liq. Cryst., 30, 565.