Generation of patterned color images in polymer film with photogenerated base

Article abstract of DOI:10.1246/cl.2000.712

Patterned color images in the polymer film have been prepared using photolabile protecting groups. Irradiation of a polymer film with 360-nm UV through a photomask followed by chemisorption of organic dyes afforded patterned color images in the polymer fi

Full text of DOI:10.1246/cl.2000.712

712
Chemistry Letters 2000
Generation of Patterned Color Images in Polymer Film with Photogenerated Base
Jong-Man Kim,* Tae-Eun Chang, Ran Hee Park,† Dong Jin Kim, *† Dong Keun Han, and Kwang-Duk Ahn
Functional Polymer Laboratory, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea
†Medicinal Chemistry Research Center, Korea Institute of Science and Technology,
P.O. Box 131, Cheongryang, Seoul 130-650, Korea
(Received March 8, 2000; CL-000231)
Patterned color images in the polymer film have been pre-
pared using photolabile protecting groups. Irradiation of a poly-
mer film with 360-nm UV through a photomask followed by
chemisorption of organic dyes afforded patterned color images
in the polymer film.
Generation of patterned functional images in polymer films
has played very important role in electronic and display indus-
tries. Accordingly, many efforts have driven to develop effi-
cient methods for patterned functional images in the polymer
films. Recently, the generation of functional images by combi-
nation of a chemical amplification (CA) process and a
chemisorption of functional dye molecules has been reported.1–3
Thus, generation of reactive species such as carboxylates or
hydroxy groups via CA process followed by interaction with
functional dyes have afforded patterned images in the polymer
films. Very recently, we also have described novel methods for
color and fluorescent functional images by employing intra- or
intermolecular hydrogen bonding approach in the polymer
film.4–7 Although the CA process has proven to be very effi-
cient to generate functional groups such as hydroxy or carboxy-
late in the exposed region of the polymer film, it has intrinsic
problems associated with generating more nucleophilic amine
moieties since the catalytic amount of acid produced in the first
step of CA process would be captured by amine groups and no
further catalytic effect would be obtained. Consequently, if
amine moieties are desired, direct generation approach using
photolabile protecting groups would be more desirable. As part
of our ongoing efforts for the development of relief and func-
tional images in the polymer film, we now report preparation of
an acrylate polymer having pendant amine groups protected
with photolabile protecting groups and application to color
imaging.
and hydrophilic nature. Copolymerization of the methacrylate
monomer 4 having pendant photolabile protecting groups with
methyl methacrylate (MMA) was carried out with a 1: 9 molar
feed ratio in 1,4-dioxane using 2,2'-azobis(isobutyronitrile)
(AIBN) as a radical initiator at 60 oC for 24 h (Scheme 2). The
copolymer 5, P(MMA/MNVMA), after precipitation in n-hexa-
The strategies employed for the synthesis of α-methylnitro-
veratryloxycarbonyl (α-MNVOC)-protected acrylate monomer
4 are presented in Scheme 1. Nitration of 3,4-dimethoxyaceto-
phenone followed by reduction with sodium borohydride pro-
vided the alcohol intermediate 2. The intermediate alcohol 2 was
converted to an activated carbonate 38 by treatment with 4-
nitrophenyl chloroformate. Conversion of the intermediate 3 to
the desired monomer 4 was achieved in two steps. Coupling of
the activated carbonate 3 with 2-(2-aminoethoxy)ethanol fol-
lowed by treatment with methacryloyl chloride readily afforded
the protected acrylate monomer 4.9 The monomer 4 was
obtained as pale yellow oil and was fully characterized by spec-
troscopic analysis.
ne, was obtained as pale yellow powder in 60% yield.
The polymer has an average molecular weight (Mw) of
26000 with compared to a polystyrene standard by gel perme-
ation chromatography (GPC) (polydiversity (PD) = 2.48). The
composition of the copolymer obtained was confirmed to have
a 1: 10 ratio between the protected monomer and MMA unit by
1H NMR spectroscopic analysis.
The 2-(2-aminoethoxy)ethanol linker was introduced
between the protecting group and polymerization unit in the
monomer 4 to make the resulting polymer both hydrophobic
In order to investigate the possibility of generation of free
amine moieties by photoirradiation,8 a solution containing the
Copyright © 2000 The Chemical Society of Japan

Chemistry Letters 2000
713
copolymer 5 (10 wt/v%) in 1,4-dioxane was spincoated on a
quartz plate with 1500 rpm for 40 s using a Headway spincoater
to make a 1.5 mm thick film. The film, then was exposed to UV
light (360 nm) and the progress was monitored by UV spec-
light. Incubation of the irradiated polymer film in a dye solution
provided the glass substrate with color image patterns.
Support for this work by the Korea Ministry of Science and
Technology through KIST program (2V00363) is greately
appreciated.
troscopy (Figure 1).
As displayed in Figure 1, absorption at the wavelength
maximum of the protecting group decreases upon irradiation.
The broad band around 400–500 nm is presumably due to the
References and Notes
1
2
3
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byproduct 7 from the photoreaction.
4
5
6
J.-M. Kim, J.-H. Kang, D.-K. Han, C.-W. Lee, and K.-D.
Ahn, Chem. Mater., 10, 2332 (1998).
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Final phase of our current investigation focused on evalua-
tion of the polymer 5 as a color imaging material.
Consequently, a 1.5 mm-thick film prepared as described above
on a glass substrate was irradiated with 360-nm UV for 10 min
(8 mW/cm2) through a photomask. The film was, then, incubat-
ed in a 1:1 mixture of t-BuOH–H2O (aq K2CO3) solution con-
taining 1 wt% of a dye 8 (C.I. Reactive Blue 225, λmax = 606
nm) at room temperature for 1 h with gentle shaking. The reac-
tive dye 8 has two electrophilic sites where free amine moieties
generated upon irradiation can attack to form covalent adducts in
the polymer film. It is clear from the Figure 2 that the irradia-
tion of the film for 10 min followed by immersing the film in a
dye solution affords chemisorption of the dye (Figure 2A),
resulting clear color patterns on the glass substrate (Figure 2B).
In summary, we have prepared a methacrylate copolymer 5
having pendant amine precursors protected with photolabile
groups. The polymer was readily spin-casted on a glass sub-
strate and generated free amine moieties upon exposure to UV
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Ahn, Chem. Lett., 2000, 360.
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7
8
9
1H NMR (200 MHz, CDCl3) δ 1.60 (d, 3H), 1.96 (s, 3H),
3.34 (brt, 2H), 3.56 (brt, 2H), 3.72 (brt, 2H), 3.94 (s, 3H),
3.98 (s, 3H), 4.30 (brt, 2H), 5.38 (brs, 1H), 5.60 (s, 1H),
6.14 (s, 1H), 6.29 (q, 1H), 7.06 (s, 1H), 7.59 (s, 1H); 13C
NMR δ 18.1, 22.0, 40.5, 56.2, 63.4, 68.8, 69.7, 107.5,
107.7, 125.9, 134.1, 136.0, 139.6, 147.7, 153.5, 155.3,
167.3, 175.8.