Photoswitchable Hydrogel Surface Topographies
FULL PAPER
Acknowledgements
Experimental Section
This research was made possible by a VICI grant of The Netherlands
Foundation for Scientific Research (NWO). The authors thank Ralf
Bovee and Dr. Xianwen Lou for performing the MS (MALDI-TOF)
measurements and for their help with the GPC analysis. Furthermore, we
thank Dr. Mark van Turnhout for his efforts to visualise the hydrogels by
using confocal microscopy.
Materials: Unless otherwise stated, all reagents and chemicals were ob-
tained from commercial sources, that is, UV-photoinitiator 2-hydroxy-1-
[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone-1-one (Irgacure 2959,
Ciba Specialty Chemicals, Switzerland), N-isopropylacrylamide (NIP-
ACHTUNGTRENNUNG AM, Sigma–Aldrich), tripropylene glycol diacrylate (TPGDA, Sigma–
Aldrich), 1H,1H,2H,2H-perfluorodecyltriethoxysilane (Sigma–Aldrich),
3-(trimethoxysilyl)propyl methacrylate (Sigma–Aldrich), and dye K160
(Risk Reactor), and used without further purification. For the detailed
synthesis of 6-((1’,3’,3’-trimethylspiro[chromene-2,2’-indolin]-6-yl)oxy)-
À
hexyl acrylate (SPA) and the SPA NIPAAM copolymer (PNS), see the
Supporting Information.
[6] S. Pedron, S. van Lierop, P. Horstman, R. Penterman, D. J. Broer, E.
[10] A. Garcꢂa, M. Marquez, T. Cai, R. Rosario, Z. Hu, D. Gust, M.
Hayes, S. A. Vail, C. D. Park, Langmuir 2006, 22, 224–229.
b) A. Athanassiou, M. I. Lygeraki, D. Pisignano, K. Lakiotaki, M.
Varda, E. Mele, C. Fotakis, R. Cingolani, S. H. Anastasiadis, Lang-
[12] a) T. Satoh, K. Sumaru, T. Takagi, K. Takai, T. Kanamori, Phys.
4955; c) K. Sumaru, M. Kameda, T. Kanamori, T. Shinbo, Macromo-
SPA: 1H NMR (400 MHz, CDCl3, 258C, TMS): d=7.17 (t, J
7.60 Hz, 1H; ArH), 7.06 (d, J(H,H)=7.03 Hz, 1H; ArH), 6.83 (t, J-
(H,H)=7.45 Hz, 1H; ArH), 6.79 (d, J(H,H)=10.26 Hz, 1H; NCCH=
CH), 6.68–6.58 (m, 3H; ArH), 6.51 (d, J(H,H)=7.84 Hz, 1H; ArH), 6.40
(d, (H,H)=17.34 Hz, 1H; trans-HC=C), 6.12 (dd, (H,H)=17.30,
10.70 Hz, 1H; H2C=CH), 5.82 (d, J(H,H)=10.41 Hz, 1H; cis-HC=C),
5.69 (d, J(H,H)=10.08 Hz, 1H; NCCH=CH), 4.17 (t, J(H,H)=6.58 Hz,
2H; OCH2), 3.89 (t, J(H,H)=6.38 Hz, 2H; ArOCH2), 2.72 (s, 3H;
NCH3), 1.81–1.66 (m, 4H; ROCH2CH2), 1.53–1.39 (m, 4H; alkane CH2),
1.30 (s, 3H; CCH3), 1.16 ppm (s, 3H; CCH3); 13C NMR (100 MHz,
CDCl3, 258C, TMS): d=166.31, 152.54, 148.51, 148.23, 136.83, 130.50,
129.28, 128.58, 127.53, 121.45, 120.19, 119.05, 118.97, 115.90, 115.45,
112.23, 106.71, 103.80, 68.44, 64.53, 51.60, 29.27, 28.93, 28.57, 25.84, 25.77,
25.75, 20.24 ppm; MS (MALDI TOF): m/z calcd for C28H33NO4: 447.24
[M]+; found: 447.31.
ACHTUNGTRNE(NUNG H,H)=
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
J
N
JACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
PNS: 1H NMR (400 MHz, [D7]DMF, 258C): d=7.50 (br s, 34H; NH),
7.14 (dd, J H,H)=7.40 Hz, 3H), 7.05 (d, J
6.84 (br s, 1H), 6.80 (t, J(H,H)=7.36 Hz, 1H), 6.75 (d, J
1H), 6.59 (dd, J(H,H)=12.59, 8.21 Hz, 2H), 5.83 (d, J(H,H)=10.12 Hz,
1H), 3.96 (s, 45H; (CH3)2CH), 2.27–2.16 (m, 40H; backbone H), 1.81–
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
1.38 (m, 80H; backbone H), 1.13 ppm (s, 242H; CHACTHNUTRGNE(UNG CH3)2)); Mw
ꢀ15000; PDIꢀ2.4.
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Sens. Actuat. A 2007, 2, 176–184.
Substrate preparation: Glass substrates were cleaned by sonication
(EtOH, 15 min), followed by treatment in a UV-ozone photoreactor
(Ultra Violet Products, PR-100, 20 min). The surface of the glass sub-
strates was modified by spin-coating a solution of 3-(trimethoxysilyl)-
propyl methacrylate (1% v/v in a water/isopropanol mixture, 1:1) or
1H,1H,2H,2H-perfluorodecyltriethoxysilane (1% v/v in EtOH) onto the
activated glass substrate for 45 s at 3000 rpm. After curing for 10 min at
1008C, the substrates were ready to use.
Sample preparation: For the freestanding films, a cell that consisted of
two (perfluorodecyltriethoxysilane-functionalised) glass substrates, with a
spacing of about 55 mm, was prepared. At 1108C, these cells were capilla-
ry filled with mixtures of NIPAAM, SPA, TPGDA, and Irgacure 2959 in
the molten state. Illumination for 300 s at the same temperature (unfil-
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romolecules 2012, 45, 8008–8012.
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[21] J. T. C. Wojtyk, A. Wasey, N.-N. Xiao, P. M. Kazmaier, S. Hoz, C.
[22] K. Sumaru, K. Ohi, T. Takagi, T. Kanamori, T. Shinbo, Langmuir
[23] S. Tsoi, D. J. Broer, C. W. M. Bastiaansen, M. G. Debije, Opt. Ex-
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M. J. Escuti, C. W. M. Bastiaansen, D. J. Broer, U. S. Schubert, J.
tered spectrum of
a collimated EXFO Omnicure S2000 lamp,
48 mWcmÀ2 intensity in the range 320–390 nm) resulted in fully polymer-
ised films. In the case of the substrate-attached patterned films, the cell
consisted of an upper perfluorodecyltriethoxysilane-functionalised glass
slide and a lower propyl-methacrylate-functionalised glass slide, with a
spacing of about 55 mm. The cells were placed onto a black surface to
minimise polymerisation in non-exposed areas, owing to additional opti-
cal effects that were caused by the reflection of light that had already
passed through the sample. A mask was placed on top of the sample and
the sample was exposed (50s, 13.5 mWcmÀ2 intensity in the range 320–
390 nm). Afterwards, the mask was removed and the cell was fully ex-
posed for another 300 s (48 mWcmÀ2 intensity in the range 320–390 nm).
[25] F. Xia, H. Ge, Y. Hou, T. Sun, L. Chen, G. Zhang, L. Jiang, Adv.
Photoactivation of the films and solutions: Light irradiation of the films
and solutions was performed by using an EXFO Omnicure S2000 lamp
and the desired wavelengths were selected by using a 400 nm cut-on filter
(Newport FSQGG400, 100 mWcmÀ2 in the range 395–445 nm).
Received: March 5, 2013
Published online: July 2, 2013
Chem. Eur. J. 2013, 19, 10922 – 10927
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
10927