Fine wettability control created by a photochemical combination method for inkjet printing on self-assembled monolayers

Article abstract of DOI:10.1002/adma.201104277

Wettability tuning for organic solvents is demonstrated with the "combination method", a reversal of the conventional "cleavage method". Several advantages are inherent to this method: for example, the syntheses are simple, various surface-active groups c

Full text of DOI:10.1002/adma.201104277

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Fine Wettability Control Created by a Photochemical
Combination Method for Inkjet Printing on Self-Assembled
Monolayers
Youichi Tsuchiya, Shuichi Haraguchi, Masashi Ogawa, Tomohiro Shiraki,
Hidenobu Kakimoto, Osamu Gotou, Takeshi Yamada, Kenji Okumoto, Shuhei Nakatani,
Kei Sakanoue, and Seiji Shinkai*
Printing methods such as inkjet, nozzle jet, gravure, screen,
and so forth are important patterning techniques that are indis-
pensable in nanotechnologies. In particular, inkjet printing is
one of the most promising methods for accurately and rapidly
depositing minute amounts of functional materials in a large
area at low cost. Therefore, much effort has been devoted
towards fine tuning this inkjet printing method as a versatile
tool useful for various industrial processes. For example, man-
ufacturing of multicolor polymer light-emitting diode (PLED)
displays is one of the potential applications made possible by
this method.[1] One must recognize, however, that the presently
used “physical” method utilizing the boundary dams to store
ink droplets is still at a stage requiring some improvement. For
example, the bleeding of ink droplets and the ink mixing caused
by overflow from the boundary dams are very critical problems
that need to be solved for the production of fine textures. At
present, various kinds of molds have been developed in order to
overcome these problems. However, the fundamental require-
ments of low cost and low energy sources are not fully satisfied,
and therefore further development of a new, innovative method
is highly desirable.
with the greatest potential to satisfy the above-mentioned
requirements. Typical examples are photocleavage and a pho-
toinduced structural change methods, which have so far been
studied by many research groups.[2] Most studies have focused
on the wettability change in an aqueous system (i.e., hydropho-
bicity vs. hydrophilicity), whereas few studies have reported the
control of the wettability change in organic solvents (i.e., sol-
vophobicity versus solvophilicity). Generally saying, the surface
energy of organic solvents is much lower than that of water
and, as a result, a larger variation of the substrate surface
energy is necessary in order to apply the inkjet printing tech-
nique to organic solvents. This situation has made the practical
application of this “chemical” method in organic solvents very
difficult. Until now, most studies adopted disconnection of
fluoroalkane groups in order to convert a solvophobic surface
to a solvophilic surface. This method can be basically classified
as a “cleavage method” (Figure 1, left). For example, Takahara
and coworkers showed that decomposition of a fluoroalkylsi-
lane monolayer (i.e., cleavage of the Si-C bond) using vacuum
ultraviolet (VUV) light induces a big difference in the wetting
properties not only for water but also for organic solvents (e.g.,
hexadecane, surface tension γ1 = 27 mN m−1, contact angle
change from 66° to less than 2°).[3] However, this method
requires a high-energy source and is not suitable for large-area
processing. More recently, Fukushima et al. showed another
efficient low-energy method utilizing a caged compound, in
which a nitrobenzyl group is disconnected by 365 nm light
irradiation.[4] We noticed, however, that this cleavage method
suffers from several drawbacks. First, a molecule useful for
this method has to integrate three different components within
one molecule: the substrate-reactive group, the photoreactive
group, and the surface-active group. Furthermore, functional
groups that can be cleaved by a low-energy light source are
very limited. As a result, the design and synthesis of such
multifunctional molecules become very complicated and very
difficult. Second, if the bond-cleavage reaction does not pro-
ceed completely, the unreacted functional group remains on
the surface. This hidden active group may cause serious prob-
lems in the subsequent treatment. Third, a fragment group
produced by the bond-cleavage reaction inevitably occupies the
surface of the resultant substrate. To allocate super-solvopho-
bicity or super-solvophilicity to such fragment groups is rather
difficult. Therefore, the preparation route to such a complex
molecule usually consists of many synthetic steps and cannot
satisfy the requirement of low-cost preparation.
In contrast to “physical” methods, “chemical” methods utilizing
control of the surface wettability represent alternative methods
Dr. Y. Tsuchiya, Dr. T. Shiraki
Institute of Systems
Information Technologies
and Nanotechnology (ISIT)
203-1 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
Dr. S. Haraguchi, Dr. M. Ogawa
Graduate School of Engineering
Kyushu University
744 Moto-oka, Nishi-ku, Fukuoka, 819-0395, Japan
H. Kakimoto, O. Gotou, T. Yamada
Tsukuba Research Laboratory
Sumitomo Chemical Co., 6 Kitahara, Tsukuba 300-3294, Japan
Dr. K. Okumoto, S. Nakatani, Dr. K. Sakanoue
Image Devices Development Center
Panasonic Cooperation
19 Nishikujo-kasuga-cho, Minami-ku, Kyoto 601-8413, Japan
Prof. S. Shinkai
Institute for Advanced Study
Kyushu University
203-1 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
E-mail: shinkai_center@mail.cstm.kyushu-u.ac.jp
DOI: 10.1002/adma.201104277
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Figure 1. Schematic illustrations of the mechanisms of a “cleavage
method” (left) and a “combination method” (right).
Here, it occurred to us that a reverse approach, that is, a
“combination method”, might be designed more simply and
more practically (Figure 1, right).[5] We can share the roles of
the three components between two independent molecules:
that is, one molecule, for the first layer, contains a substrate-
reactive group and a combination group and the other mole-
cule, for the second layer, contains a surface-active group and
a combination group. In this approach, two molecules can be
synthesized separately with much shorter synthetic routes. Fur-
thermore, one can easily introduce the desired surface-active
group that is unaffected by the reaction of the first surface treat-
ment. In this Communication, we offer a new photopatterning
concept utilizing a “combination method” to control the wet-
tability of the substrate surface with respect to organic solvents.
To demonstrate the potential of this idea, we have chosen an
anthracene photodimerization reaction for the connection reac-
tion of the first layer with the second layer.[6] This connection
can be achieved by a low-energy UV light source (365 nm). The
structural details of this method are shown in Figure 2, which
are much simpler than those used in the “cleavage method”.
To immobilize the anthracene moiety on the silicon dioxide
surface, a triethoxysilyl group is introduced into the first-layer
molecule. On the other hand, three fluoroalkane chains are
introduced into the second-layer molecule in order to create a
super-solvophobic surface.
Figure 3. Absorbance spectrum of the substrate after deposition of the
first layer of anthracene (An-Si).
undecyloxy]phenylmethyl ester (An-FG) used for the second
layer was synthesized from gallic acid methyl ester in three
steps (see the Experimental Section).[7] After an indium tin
oxide (ITO) surface (1.0 cm × 2.0 cm) had been cleaned, it was
immersed in a 4.0 mm An-Si solution (dry CH2Cl2/dry toluene =
1:1 v/v) and left for 5 min at 20 °C. The substrate was slowly
pulled out of the solution and then baked at 110 °C for 5 min.
Finally, it was washed with chloroform several times and dried
in a nitrogen gas flow. The reaction progress was monitored by
UV-vis absorbance spectrometry.
The amount of anthracene group deposited on the ITO
surface was estimated by a UV-vis absorption spectroscopic
method. As shown in Figure 3, the absorption band character-
istic of the anthracene group appeared at 350–400 nm. From
the extinction coefficient of this band, the amount of depos-
ited An-Si was estimated to be 2.2 × 10−11 mol cm−2: that is,
one An-Si molecule exists per 7.6 nm2. As the molecular size
of An-Si is estimated to be ca. 1.5 nm2, it follows that ca. 20%
of the ITO surface is covered by An-Si molecules. This result
implies that An-Si molecules occupy a “moderate” percentage of
the substrate surface (not full occupation). This situation seems
to be more advantageous for deposition of the second layer,
because the “moderate” coverage of An-Si not only suppresses
the undesired photodimerization between An-Si molecules on
the surface but also provides the open space for second-layer
An-FG molecules to be inserted in the first layer with the aid of
the anthracene–anthracene π−π interaction.[8] We noticed that
in order to adjust the coverage percentage to this level, the use
of toluene as a co-solvent is indispensable. Presumably, toluene
molecules solvate the anthracene moiety of An-Si and suppress
the high percentage coverage of the substrate surface. At this
stage, the contact angles for distilled water and anisole were 65°
and 0°, respectively: that is, the first layer is able to show some
hydrophobicity but no solvophobicity at all.
N-(9-Anthracenecarbonyl)aminopropyltriethoxylsilane (An-
Si) used for the first layer was synthesized by condensation
of 9-anthracenecarboxylic acid and aminopropyltriethoxylsi-
lane. 9-Anthracenecarobxylic acid 3,4,5-tris[(heptadecafluoro)-
The ITO substrate was immersed in a 1.0 mmol dm−3 An-FG
solution (for used solvents, see Table 1) for 10 min. Then
the substrate was pulled out slowly and dried in a stream of
nitrogen gas. After a patterning mask had been placed on the
Figure 2. Structural details of the “combination method” using an anthra-
cene photodimerization reaction.
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Table 1. Static contact angles for anisole.
Solvents
Without UV
With UV
73o
<5o
<5o
<5o
Tridecafluorohexyl iodide
Tridecafluorohexyl iodide/chloroform (1:1)
Toluene
19o
<5o
ITO substrate, photodimerization of the anthracene groups
was carried out with UV light irradiation (365 nm, 5 mW cm−2)
for 20 min. The ITO substrate was rinsed several times with
chloroform and trifluorotoluene and thoroughly dried under a
nitrogen gas flow. As expected, the photoirradiated area strongly
repulsed anisole droplets and most of them gathered on the
masked area (Figure 4), indicating that photodimerization takes
place sufficiently and the substrate surface is now covered with
fluorocarbon chains.
As summarized in Figure 5 and Table 1, when tridecafluoro-
hexyl iodide was used as the solvent, the contact angle of the
photoirradiated area was surprisingly enhanced up to 73°. On
the other hand, that of the masked area was only 4°. The results
clearly indicate that the anthracene photodimerization satisfac-
torily proceeds between An-Si in the first layer and An-FG in the
second layer and creates a super-solvophobic surface. In con-
trast, when toluene was used as the solvent, the contact angle
for both the photoirradiated area and the masked area was less,
ca. 4°. Even when tridecafluorohexyl iodide solvent was diluted
with the same volume of chloroform, the contact angle after
photoirradiation was reduced to 19° (Table 1). The dramatic sol-
vophobicity change means that the π−π interaction between the
anthracene group of An-Si in the first layer and that of An-FG
in the second layer is extremely solvent-dependent. Thus, one
may take the contribution of another solvophobic force into
consideration when we used tridecafluorohexyl iodide as the
reaction medium: presumably, An-FG has three fluorocarbon
chains and behaves as a super-solvophobic molecule, so that it
may form a micellar aggregate in toluene or in tridecafluoro-
hexyl iodide/chloroform (1:1) due to the strong solvophobic
nature. This kind of aggregation is very unfavorable for reaction
of An-FG with the first-layer An-Si. Also, in order to reconfirm
the importance of photoirradiation, we carried out a few refer-
ence experiments (Table 2). It is clearly seen from Table 2 that
the high contact angle of 73° is achieved only when the sample
was prepared through the photoirradiation treatment.
Figure 4. Photograph demonstrating the creation of a super-solvophobic
area by UV light irradiation (solvent, anisole droplets). The ITO substrate
was treated in tridecafluorohexyl iodide containing An-FG.
molecules are deposited on the substrate surface in a moderate
density from a toluene solution, ii) An-FG molecules are dis-
persed in a fluorocarbon solvent without forming a micellar
aggregate and adsorbed on the first-layer surface owing to the
π−π interaction between the anthracene groups and the sol-
vophobic force, and iii) photodimerization proceeds between
the first-layer anthracene and the second-layer anthracene. As
one An-FG molecule has three fluorocarbon chains, the super-
solvophobic surface is created only in the photoirradiated area.
In conclusion, the study presented here demonstrates that
wettability tuning for organic solvents can be easily achieved
with the “combination method”, a reverse process compared to
the conventional “cleavage method”. This method has several
advantages: for example, i) the syntheses of both the first-layer
molecule and the second-layer molecule are simple, ii) one can
employ various surface-active groups because they are designed
independently of the combination group, and iii) the reaction
proceeds with a low-energy light source. In addition, if we
irradiate the final product with a shorter wavelength, dimeric
anthracene is decomposed to monomeric anthracene: this
means that the second layer can be attached “reversibly”. The
sole drawback of the present method is the use of fluorocarbon
solvents. However, as their properties are very different from
The foregoing results consistently allow us to propose a
new deposition method illustrated in Figure 2: that is, i) An-Si
Figure 5. Optical micrography images of static wetting for an anisole droplet on a glass substrate treated with An-FG solutions. Solvents used: toluene
(left), tridecafluorohexyl iodide/chloroform (1:1) (center), and tridecafluorohexyl iodide (right).
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Table 2. Static contact angles for anisole.
acetate and the solution was washed with distilled water and dried over
anhydrous sodium sulfate. Purification was carried out by recrystallization
with acetone, which afforded 2.0 g of 1 (1.3 mmol, 89%).
No.
1
1st layer
2nd layer
UV

×
θ
1: m.p. = 88 °C, 1H NMR (400 MHz, CDCl3): δ = 7.28 (s, 2H;
Ph(2,6)), 4.11 (t, J = 5.9 Hz, 4H; Ph(3,5)–OCH2CH2 –), 4.05 (t, J =
5.9 Hz, 2H; Ph(4)–OCH2CH2 –), 3.89 (s, 3H; –CH3), 2.45-2.20 (m, 6H;
–OCH2CH2CH2 –), 2.20–2.08 (m, 4H; (3,5)–CH2CH2CF2 –), 2.08–1.95
(m, 2H; (4)–CH2CH2CF2 –).



×


×
73°
<5°
<5°
<5°
2
3
×
Synthesis of 2: A dry tetrahydrofuran (THF; 10 mL) solution containing
1 (1.5 g, 1.0 mmol) and lithium aluminum hydride (49.5 mg, 1.9 mmol)
was refluxed for 2 h under an argon atmosphere. The resulting solution
was cooled to room temperature and the solvent was removed.
Purification was carried out with recrystallization with acetone, which
afforded 1.4 g of 2 (0.91 mmol, 91%).
4


other hydrocarbon solvents, this problem would be solved by
recovery or recycling. We believe, therefore, that the present
“combination method”, which possesses several advantages
compared to the conventional “cleavage method”, should be fur-
ther developed as a promising technique for fine surface tuning
applicable to inkjet printing and related technologies.
2: m.p. = 72 °C, 1H NMR (400 MHz, CDCl3): δ = 6.59 (s, 2H; Ph(2,6)),
4.60 (d, J = 6.0 Hz, 2H; Ph(1)–CH2OH), 4.06 (t, J = 5.9 Hz, 4H; Ph(3,5)–
OCH2CH2 –), 3.97 (t, J = 5.9 Hz, 2H Ph(4)–OCH2CH2 –), 2.45–2.20 (m,
6H; –OCH2CH2CH2 –), 2.26 (t, J = 6.0 Hz, 1H; –CH2OH), 2.20–2.06 (m,
4H; (3,5)–CH2CH2CF2 –), 2.06–1.95 (m, 2H; (4)–CH2CH2CF2 –).
Synthesis of An-FG:[9] 9-Anthracenecarboxylic acid (17.3 mg, 7.8 ×
10−2 mmol), dry dichloromethane (5 mL), dry dimethylformamide
(DMF; 50 μL), and thionyl chloride (13 mg, 0.11 mmol) were stirred for
0.5 h at room temperature and then refluxed for 4 h under an argon
atmosphere. After this treatment, the solvent was removed in vacuo and
then compound 2 (100 mg, 6.5 × 10−2 mmol), trifluorotoluene (10 mL),
and pyridine (0.5 mL) were charged. The mixture was stirred at 45 °C for
15 h. The resulting solution was cooled to room temperature, washed
with distilled water, and dried over anhydrous sodium sulfate. Purification
was carried out by recrystallization with acetone, which afforded 31 mg
An-FG (1.8 × 10−2 mmol, 27%).
Experimental Section
Materials: Unless otherwise specified, all starting materials and
solvents were purchased from Tokyo Kasei Chemicals, Wako Chemicals,
Kishida Chemicals, and Aldrich and used as received. ITO substrates
were obtained from Sumitomo Chemical Co. and were cut into 20 mm
pieces.
Instruments: 1H NMR spectra were obtained on a Bruker DRX600
spectrometer. Mass spectra were recorded on a JEOL JMS-T100TD or
Bruker Reflex III. UV-vis spectra were acquired on a Shimadzu UV-2500PC
spectrometer. Contact angle was measured by the following method. A
10 μL droplet was placed on the sample surface with a microsyringe.
Static images of droplets were shot by a video microscope (VZM300
Video System, Edmund Optics Japan, Ltd.).
1
An-FG: m.p. = 90 °C, H NMR (400 MHz, CDCl3/C6F6): δ = 8.02 (s,
1H; An(10)), 7.72 (dd, J = 6.9, 2.1 Hz, 2H; An(1,8)), 7.59 (dd, J = 6.9,
2.1 Hz, 2H; An(4,5)), 7.01 (m, 4H; An(2,3,6,7)), 6.66 (s, 2H; Ph(2,6)),
4.56 (s, 2H; Ph(1)–CH2O –), 4.19 (t, J = 5.9 Hz, 4H; Ph(3,5)–OCH2CH2 –),
4.09 (t, J = 5.9 Hz, 2H Ph(4)–OCH2CH2 –), 2.60–2.35 (m, 6H;
–OCH2CH2CH2 –), 2.35–2.22 (m, 4H; (3,5)–CH2CH2CF2 –), 2.22–2.05
(m, 2H; (4)–CH2CH2CF2 –).
Chemical syntheses: Compounds An-FG and An-Si were prepared
according to Scheme 1.
Synthesis of An-Si: 9-Anthracenecarboxylic acid (1.0 g,
4.5 mmol), dicyclohexylcarbodiimide (DCC; 0.93 g, 4.5 mmol), and
hydroxybenzotriazole (HOBt; 0.61 g, 4.5 mmol) were dissolved in dry
dichloromethane (60 mL). After triethylamine (0.45 g, 4.5 mmol) and
3-aminopropyltriethoxysilane (1.0 g, 4.5 mmol) had been added, the
reaction mixture was stirred for 24 h at room temperature under an
argon atmosphere. When the reaction was complete, the solvent was
removed in vacuo. The resultant solid was purified
by column chromatography (Wako gel C-300,
chloroform), which afforded 360 mg (0.85 mmol,
20%) An-Si.
Synthesis of 1: Gallic acid methyl ester (268 mg, 1.5 mmol),
heptadecafluoroundecyl iodide (3.0 mg, 5.1 × 10−1 mmol), 18-crown-6
(115 mg, 4.3 × 10−2 mmol), and potassium carbonate (760 mg, 5.5 mmol)
in dry acetone (20 mL) were refluxed for 3 nights under an argon
atmosphere. The resulting solution was cooled to room temperature and
the solvent was removed in vacuo. The residue was dissolved in ethyl
An-Si: m.p. = 109 °C, 1H NMR (300 MHz, CDCl3):
δ = 8.46 (s, 1H; An(10)), 8.07 (dd, J = 6.9, 2.1 Hz, 2H;
An(1,8)), 7.99 (dd, J = 6.9, 2.1 Hz, 2H; An(4,5)), 7.48
(m, 4H; An(2,3,6,7)), 6.42 (br, 1H; –CONHCH2 –),
3.75 (q, J = 6.9 Hz, 6H; –OCH2CH3), 1.90 (m, 2H;
–NHCH2CH2 –), 1.25 (m, 2H; –CH2CH2CH2 –),
1.12 (t, J = 6.9 Hz, 9H; –OCH2CH3), 0.77 (t, J =
8.1 Hz, 2H; –CH2CH2Si –), MALDI-TOF-MS (m/z):
426.2 [M + H]+.
Preparation of thin-film substrates: ITO substrates
were pretreated by the following method. Substrates
were immersed in alkali detergent for 15 min with
sonication and then rinsed in Milli-Q water and
isopropyl alcohol with the aid of sonication for
15 min each. After washing, the substrates were
activated by O2 plasma treatment to give the Si-OH
terminated surface, which is useful for immobilizing
organosilane molecules.
Preparation of a thin-film first layer: Substrates
Scheme 1. Chemical synthesis of An-FG and An-Si.
were immersed in 4 mmol dm−3 An-Si solution (dry
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CH2Cl2/dry toluene 1:1) for 5 min. After immersion, the substrates were
slowly pulled out of the solution and baked at 110 °C for 5 min. The
substrates were washed with chloroform and then dried by a N2 gas flow.
The reaction progress was characterized by the absorbance spectra.
Preparation of a thin-film second layer: Substrates were immersed in
1 mmol dm−3 An-FG solution (perfluoromethylcyclohexane, tridecafluoro
iodide, chloroform) for 10 min. After immersion, the substrates were
slowly pulled out and then dried by a N2 gas flow. After a patterning mask
had been placed on the substrate, photodimerization of anthracene was
carried out under UV irradiation (365 nm, ca. 5 mW cm−2) for 20 min.
After this treatment, the substrates were rinsed several times with
chloroform and trifluorotoluene, and then thoroughly dried by a N2 gas
flow.
N. Wanichacheva, C. R. Lambert, W. G. McGimpsey, Langmuir 2007,
23, 13181–13187.
[3] a) M. Morita, T. Koga, H. Otsuka, A. Takahara, Langmuir 2005, 21,
911–918; b) I. H. Bechtold, E. A. Oliveira, Mol. Cryst. Liq. Cryst. 2005,
442, 41–49.
[4] H. Fukushima, H. Takiguchi, T. Shimoda, R. J. Bushby, S. Evans,
J. P. Jeyadevan, K. Critchley, (Seiko Epson Corp.), Japanese Patent JP
2006-104155 A, 2006 and related patents.
[5] W. S. Dillmore, M. N. Yousaf, M. Mrksich, Langmuir 2004, 20,
7223–7231.
[6] a) M. A. Fox, M. D. Wooten, Langmuir 1997, 13, 7099–7105;
b) V. Chechik, R. M. Crooks, C. J. M. Stirling, Adv. Mater. 2000, 12,
1161–1171.
[7] a) D. Cao, S. Dobis, C. Gao, S. Hillmann, H. Meier, Chem. Eur.
J. 2007, 13, 9317–9323; b) V. Percec, M. Glodde, M. Peterca,
A. Rapp, I. Schnell, H. W. Spiess, T. K. Bera, Y. Miura,
V. S. K. Balagurusamy, E. Aqad, P. A. Heiney, Chem. Eur. J. 2006,
12, 6298–6314; c) A. P. Narrainen, L. R. Hutchings, I. Ansari,
R. L. Thompson, N. Clarke, Macromolecules 2007, 40, 1969–1980.
[8] a) S. L. Brandow, M.-S. Chen, C. S. Dulcey, W. J. Dressick, Langmuir
2008, 24, 3888–3896; b) M.-S. Chen, S. L. Brandow, T. L. Schull,
D. B. Chrisey, W. J. Dressick, Adv. Funct. Mater. 2005, 15, 1364–1375;
c) W. J. Dressick, P. F. Nealey, S. L. Brandow, Proc. SPIE 2001, 4343,
294–305; d) V. Chechik, R. M. Crooks, C. J. M. Stirling, Adv. Mater.
2000, 12, 1161–1171.
[9] In the mass analysis using direct analysis in real time (DART) time-
of-flight mass spectrometry (TOF-MS) and matrix-assisted laser
desorption/ionization (MALDI) TOF-MS, the signal of the formula
weight was not found at around 1740.8. The main peak was found
at 1519.3 (in DART) or 1059.3 (in MALDI), which could be assigned
as a fragment peak. Thus, we identified this compound mainly by
NMR methods.
Acknowledgements
This work was partially supported by the MEXT, Grant-in-Aid for Scientific
Research B (23350070).
Received: November 3, 2011
Published online: January 17, 2012
[1] a)B.-J. Gans, P. C. Duineveld, U. S. Schubert, Adv. Mater. 2004, 16,
203–213; b) H. Sirringhaus, T. Kawase, R. H. Friend, T. Shimoda,
M. Inbasekaran, W. Wu, E. P. Woo, Science 2000, 290, 2123–2126;
c) E. Menard, M. A. Meitl, Y. Sun, J.-U. Park, D. J.-L. Shir, Y.-S. Nam,
S. Jeon, J. A. Rogers, Chem. Rev. 2007, 107, 1117–1160.
[2] a)D. Dattilo, L. Armelao, G. Fois, G. Mistura, M. Maggini, Langmuir
2007, 23, 12945–12950; b) K. Ichimura, S.-K. Oh, M. Nakagawa,
Science 2000, 288, 1624–1626; c) P. F. Driscoll, N. Purohit,
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2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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