SUPPORTING INFORMATION
Photobase Generators Derived from trans-o-Coumaric Acid for Anionic UV
Curing Systems without Gas Generation
Koji Arimitsu*, Yuri Takemori, Atsushi Nakajima, Ayaka Oguri, Masahiro Furutani, Takahiro Gunji,
Yoshimoto Abe
CONTENTS
1. Equipment and materials
2. Syntheses of photobase generators (PBGs) 1 and 2
3. UV spectrum of coumarin in methanol
4. Photodecomposition of PBG 1
5. Fabrication of cured PGMA films with PBG 1
6. Time course of FT-IR spectra of a PGMA film containing PBG 1
7. Fabrication of cured PMAS films with PBG 2
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1. EQUIPMENT AND MATERIALS
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H NMR spectra were obtained using a JEOL JNM-EX300. 13C NMR spectra were obtained using a JEOL
JNM-EX75. FT-IR spectra were measured using a JASCO FT/IR-410 or a JASCO FT/IR-6100. UV-vis spectra
were obtained with a Shimadzu MultiSpec-1500. Melting points were measured using a Yanaco New
Science MP-S3.
Films were fabricated with a MIKASA MS-A100 spin coater. A Matsunaga SUPERCURE-203S Hg–Xe lamp
was used for UV irradiation. Film thicknesses were measured with a Dektak3ST (Ulvac, Inc.). The pencilhardness test was performed with a Yasuda No. 553-M1.
The reagents used were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan), Kanto
Chemical Co., Inc. (Tokyo, Japan) and Wako Pure Chemical Industries, Ltd. (Osaka, Japan). All of the
chemicals were used without further purification.
2. SYNTHESES OF PHOTOBASE GENERATORS (PBGS) 1 AND 2 (SCHEMES 1 AND 2)
2.1. Synthesis of PBG 1
O
OH
O
OH
EDC, THF
+
OH
N
H
r.t., 15 h
H2N
PBG 1
SCHEME 1 Synthesis of PBG 1.
1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (2.1 g, 11 mmol) and DCM were added to
a solution of trans-o-coumaric acid (1.8 g, 11 mmol) in dry THF. Cyclohexylamine (0.99 g, 10 mmol) was
added to the mixture, and stirred at room temperature for 15 h. Water was added to the mixture, and
the organic layer was further washed three times with 10% HCl aqueous solution, water and saturated
NaHCO3 aqueous solution for each, followed by drying with MgSO4. After removing the solvent,
recrystallization was performed with chloroform to give PBG 1 as a white crystal in 46% yield (2.1 g). 1H
NMR (300 MHz, acetone-d,  ppm): 1.71–2.09 (10H, m, cyclohexyl), 3.80 (1H, m, –N–CH<), 6.71 (1H, d, J
= 16 Hz, ArCH=CH–), 6.82–7.20 (4H, m, aromatic), 7.46 (1H, dd, J = 1.5, 7.7 Hz, –NH–), 7.85 (1H, d, J = 16
Hz, ArCH=CH–), 8.96 (1H, s, –OH). FT-IR (KBr, cm–1): 3300 (O–H), 3100 (C–Haromatic), 2900 (C–Halkyl), 2850
(C–Halkyl), 1650 (C=O), 1550 (C–H). Anal. calcd for C15H19N1O2: C, 73.4; H, 7.81; N, 5.71. Found: C, 73.5; H,
8.00; N, 5.70. mp: 240–241 C.
2.2. Synthesis of PBG 2
O
OH
2
O
OH
+
H2N
Si
O
2
EDC, DMF
OH
N
H
Si
O
r.t., 24 h
2
PBG 2
SCHEME 2 Synthesis of PBG 2.
2
1,3-Bis(aminopropyl)tetramethoxydisiloxane (3.4 mL) was added to a solution of trans-o-coumaric acid
(4.1 g, 25 mmol) in DMF (60 mL). 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (8.6 g,
45 mmol) was then added to the mixture, and stirred at room temperature for 24 h. Ethyl acetate was
added to the mixture, and the organic layer was washed three times with water and 10% HCl aqueous
solution for each, followed by drying with MgSO4. After removing the solvent, the residue was dissolved
in THF and reprecipitated with benzene. PBG 2 was obtained as a white solid in 23% yield (1.5 g). 1H
NMR (300 MHz, DMSO-d, , ppm): 0.51 (4H, t, J = 6.7 Hz, SiCH2–), 1.45 (4H, dt, J = 6.7, 7.9 Hz, –
CH2CH2CH2–), 3.14 (4H, q, J = 7.9 Hz, –NHCH2–), 6.65 (2H, d, J = 16 Hz, ArCH=CH–), 6.78–7.42 (8H, m,
aromatic), 7.62 (2H, d, J = 16 Hz, ArCH=CH–), 8.06 (2H, t, J = 5.8 Hz, –NH–), 9.99 (2H, s, –OH). 13C NMR
(75 MHz, DMSO-d, , ppm): 14.7, 23.4, 41.6, 115.8, 118.7, 121.4, 127.7, 130.3, 134.2, 156.3, 165.5.
Decomposition point: 220 C.
3. UV SPECTRUM OF COUMARIN IN METHANOL
1.2
1
Abs.
0.8
0.6
0.4
0.2
0
190
240
290
340
390
Wavelength ( nm )
FIGURE S1 UV spectrum of coumarin in methanol.
4. PHOTODECOMPOSITION OF PBG 1
(a)
methanol
coumarin
(b)
5
10
15
[min]
20
25
20
25 [min]
PBG 1
5
10
15
(c)
coumarin
5
10
15
20
25
[min]
FIGURE S2 Gas chromatography chart of PBG 1 in methanol. (a) Coumarin (control), (b) PBG 1 before UV
irradiation and (c) PBG 1 after UV irradiation.
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5. FABRICATION OF CURED PGMA FILMS WITH PBG 1
FIGURE S3 Procedure for fabricating cured PGMA films. Amines photogenerated by PBG 1 are expected
to react with the epoxy groups of PGMA to form cross-linking networks.
6. TIME COURSE OF FT-IR SPECTRA OF A PGMA FILM CONTAINING PBG 1
FIGURE S4 (a) Time course of FT-IR spectra of a PGMA film containing PBG 1 after UV irradiation and
subsequent post-baking at 140 C for 0–7.5 min. (b) Change in peak intensity of the epoxy group during
heating.
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7. FABRICATION OF CURED PMAS FILMS WITH PBG 2
FIGURE S5 Procedure for fabricating cured PMAS films (film thickness: ca 1.1 m by bar coating).
Diamines photogenerated by PBG 2 are expected to catalyse the polycondensation reaction of the
trimethoxysilyl groups of PMAS to form cross-linking networks.
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