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3
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0042988238
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-
note
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For a conventional 10-μm-thick optical cell with strong anchoring (parallel to surface) that is filled with the liquid crystal PEBAB, the onset of the electric field-induced transition in the orientation of the bulk liquid crystal [Freedericksz transition (36); Fig. 1A, 1] occurs at ∼3 V. The change in optical appearance is 90% complete at ∼6 V (38). The threshold voltage required for the onset of an electric field-induced change in the orientation of a liquid crystal can be reduced by use of hybrid aligned cells (39) or large pretilts (40) in the orientation of the liquid crystal. Saturation voltages in these systems are typically greater than a few volts. Hybrid aligned cells and pretilts can likely reduce further the switching voltages reported in this paper.
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4
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0042988241
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note
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Photoisomerization of surfaces decorated with azobenzene by using ultraviolet (UV) light can also lead to surface-driven orientational transitions in liquid crystals (41).
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-
-
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5
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0032537718
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B. Comiskey, J. D. Albert, H. Yoshizawa, J. Jacobson, Nature 394, 253 (1998).
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(1998)
Nature
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-
Comiskey, B.1
Albert, J.D.2
Yoshizawa, H.3
Jacobson, J.4
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8
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-
0031003217
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P. Poulin, H. Stark, T. C. Lubensky, D. A. Weitz, Science 275, 1770 (1997).
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(1997)
Science
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-
Poulin, P.1
Stark, H.2
Lubensky, T.C.3
Weitz, D.A.4
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10
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0042988237
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note
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Water-soluble ferrocene-based surfactants have been used to generate gradients in surface tension and control contact angles of isotropic aqueous solutions (42).
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-
-
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14
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-
0041485552
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note
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We used BP because it is soluble in both 5CB and MBBA. The oxidation was initiated by heating the sample to ∼37°C. We used UV spectrophotometry and cyclic voltammetry to confirm oxidation of ferrocene to ferrocenium in the presence of BP.
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16
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0042988234
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note
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When BP was used to oxidize the ferrocene-terminated monolayer, the liquid crystal was deaerated to remove oxygen (43).
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-
-
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18
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-
0041986618
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note
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The addition of 20 mM BP to 5CB and MBBA does not measurably change the birefringence of these liquid crystals and thus their interference colors (fig. S1).
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-
-
-
20
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0042988235
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note
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The anchoring of MBBA and MBBA with BP was indistinguishable when measured on a methylterminated monolayer.
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21
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0003634709
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Springer, Berlin, ed. 2
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L. M. Blinov, V. G. Chigrinov, Electrooptic Effects in Liquid Crystal Materials (Springer, Berlin, ed. 2, 1993), p. xiv.
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(1993)
Electrooptic Effects in Liquid Crystal Materials
, vol.14
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Blinov, L.M.1
Chigrinov, V.G.2
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22
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0042487432
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-
note
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The addition of 20 to 35 mM TBAF to either 5CB or MBBA does measurably change the birefringence of these liquid crystals and thus their interference colors (figs. S2 and S3).
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-
-
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24
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0042487431
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note
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We determined the orientation of 5CB in Fig. 3, D and E, by observing the interference colors of liquid crystals in optical cells prepared using surfaces that cause known orientations of the liquid crystal. The interference colors in Fig. 3, D and E, were also obtained by chemical oxidation (BP) of ferrocenyl monolayers with an optical cell identical to that shown in Fig. 3A (figs. S4 and S5).
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-
-
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28
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0041485553
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note
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At potentials between 0 and 0.3 V, the luminosity increased with potential under crossed polars but decreased under parallel polars (Fig. 4, A and B), indicating the formation of a twisted distortion of liquid crystal within the optical cell.
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-
-
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29
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0041986614
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note
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We measured the response time by analyzing frames of a video captured at a resolution of 1/30 of a second during a step change in potential from 0 to 0.2 V.
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-
-
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30
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0041986615
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note
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When the sample was oriented at 45° with respect to one of the crossed polars, application of the overvoltage resulted in a change in color from green to pale yellow (Fig. 4C). This change in the interference color matches the change in color that was observed to accompany the out-of-plane transition of 5CB on the ferrocenium-terminated monolayers.
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32
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0035276116
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L. M. Abrantes, M. Kalaji, A. S. Viana, J. Electroanal, Chem. 500, 290 (2001).
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(2001)
J. Electroanal. Chem.
, vol.500
, pp. 290
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Abrantes, L.M.1
Kalaji, M.2
Viana, A.S.3
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33
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0033585528
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T. Kondo, S. Horiuchi, I. Yagi, S. Ye, K. Uosaki, J. Am. Chem. Soc. 121, 391 (1999).
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(1999)
J. Am. Chem. Soc.
, vol.121
, pp. 391
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Kondo, T.1
Horiuchi, S.2
Yagi, I.3
Ye, S.4
Uosaki, K.5
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40
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0033609282
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G. P. Bryan-Brown, E. L. Wood, I. C. Sage, Nature, 399, 338 (1999).
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(1999)
Nature
, vol.399
, pp. 338
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Bryan-Brown, G.P.1
Wood, E.L.2
Sage, I.C.3
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44
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0041986613
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note
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Supported in part by the Biophotonics Partnership Initiative of the National Science Foundation (ECS-0086902), the Center for Nanostructured Interface (NSF 0079983), and the Army Research Office (DAAD19-02-1-0299).
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