Abstract

As an alternative to the rubbing method, the photoalignment method has been extensively developed for liquid crystal displays owing to its various advantages including the absence of any contamination problems, feasibility of multi-domain structure formation, and low temperature processing capability. However, cinnamate-based photo-reactive materials that are widely used in photoalignment suffer from several limitations including low pretilt angle and limited control of tilted-up direction of the liquid crystals compared to that of the rubbing process. In this work, we demonstrate a simple and convenient method to generate the pretilt angle, compared to that achieved via the rubbing method, by means of a simple directional peel-off process using a photo-reactive cinnamate oligomer having flexible molecular chain.

© 2009 OSA

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    [CrossRef]
  7. K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  10. S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
  13. S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
    [CrossRef]
  14. S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
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    [CrossRef]
  18. J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
    [CrossRef]
  19. M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
    [CrossRef]
  20. T. J. Scheffer and J. Nehring, “Accurate determination of liquid-crystal tilt bias angles,” J. Appl. Phys. 48(5), 1783–1792 (1977).
    [CrossRef]
  21. H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
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    [CrossRef]

2009 (1)

2008 (2)

H. Hah, S.-J. Sung, K. Y. Cho, and J.-K. Park, “Molecular orientation of liquid crystal on polymer blends of coumarin and naphthalenic polyimide,” Polym. Bull. 61(3), 383–390 (2008).
[CrossRef]

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

2007 (1)

H. Hah, S.-J. Sung, and J.-K. Park, “Ultraviolet embossed alignment layer for flexible liquid crystal display,” Appl. Phys. Lett. 90(6), 063508 (2007).
[CrossRef]

2006 (1)

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

2005 (1)

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

2004 (4)

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

S.-J. Sung, K.-Y. Cho, and J.-K. Park, “Photo-induced liquid crystal alignment of poly(vinyl cinnamate) and fluorinated polyimide blends,” Mater. Sci. Eng. C 24(1-2), 181–184 (2004).
[CrossRef]

2002 (1)

S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
[CrossRef]

2001 (1)

S.-J. Sung, H.-T. Kim, J.-W. Lee, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorine group,” Synth. Met. 117(1-3), 277–279 (2001).
[CrossRef]

2000 (1)

K. Ichimura, “Photoalignment of liquid-crystal systems,” Chem. Rev. 100(5), 1847–1874 (2000).
[CrossRef] [PubMed]

1995 (1)

Y. Iimura, T. Saitoh, S. Kobayashi, and T. O. R. U. Hashimoto, “Liquid crystal alignment on photopolymer surfraces exposed by linearly polarized UV light,” J. Photopolym. Sci. Technol. 8(2), 257–262 (1995).
[CrossRef]

1992 (2)

M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
[CrossRef]

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

1991 (1)

W. Gibbons, P. Shannon, S. Sun, and B. Swetlin, “Surface-mediated alignment of nematic liquid crystals with polarized laser light,” Nature 351(6321), 49–50 (1991).
[CrossRef]

1988 (1)

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

1977 (1)

T. J. Scheffer and J. Nehring, “Accurate determination of liquid-crystal tilt bias angles,” J. Appl. Phys. 48(5), 1783–1792 (1977).
[CrossRef]

1972 (1)

J. Janning, “Thin film surface orientation for liquid crystals,” Appl. Phys. Lett. 21(4), 173–174 (1972).
[CrossRef]

1969 (1)

D. K. Owens and R. C. Wendt, “Estimation of the surface free energy of polymers,” J. Appl. Polym. Sci. 13(8), 1741–1747 (1969).
[CrossRef]

Ahn, D.

Ahn, H. J.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Aoki, K.

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

Baik, H. K.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Chang, H.-S.

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

Chigrinov, V.

M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
[CrossRef]

Cho, I.

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

Cho, K. Y.

H. Hah, S.-J. Sung, K. Y. Cho, and J.-K. Park, “Molecular orientation of liquid crystal on polymer blends of coumarin and naphthalenic polyimide,” Polym. Bull. 61(3), 383–390 (2008).
[CrossRef]

Cho, K.-Y.

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

S.-J. Sung, K.-Y. Cho, and J.-K. Park, “Photo-induced liquid crystal alignment of poly(vinyl cinnamate) and fluorinated polyimide blends,” Mater. Sci. Eng. C 24(1-2), 181–184 (2004).
[CrossRef]

Gibbons, W.

W. Gibbons, P. Shannon, S. Sun, and B. Swetlin, “Surface-mediated alignment of nematic liquid crystals with polarized laser light,” Nature 351(6321), 49–50 (1991).
[CrossRef]

Hah, H.

H. Hah, S.-J. Sung, K. Y. Cho, and J.-K. Park, “Molecular orientation of liquid crystal on polymer blends of coumarin and naphthalenic polyimide,” Polym. Bull. 61(3), 383–390 (2008).
[CrossRef]

H. Hah, S.-J. Sung, and J.-K. Park, “Ultraviolet embossed alignment layer for flexible liquid crystal display,” Appl. Phys. Lett. 90(6), 063508 (2007).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

Hashimoto, T. O. R. U.

Y. Iimura, T. Saitoh, S. Kobayashi, and T. O. R. U. Hashimoto, “Liquid crystal alignment on photopolymer surfraces exposed by linearly polarized UV light,” J. Photopolym. Sci. Technol. 8(2), 257–262 (1995).
[CrossRef]

Heo, Y.

Hillborg, H.

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

Hosoki, A.

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

Ichimura, K.

K. Ichimura, “Photoalignment of liquid-crystal systems,” Chem. Rev. 100(5), 1847–1874 (2000).
[CrossRef] [PubMed]

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

Iimura, Y.

Y. Iimura, T. Saitoh, S. Kobayashi, and T. O. R. U. Hashimoto, “Liquid crystal alignment on photopolymer surfraces exposed by linearly polarized UV light,” J. Photopolym. Sci. Technol. 8(2), 257–262 (1995).
[CrossRef]

Janning, J.

J. Janning, “Thin film surface orientation for liquid crystals,” Appl. Phys. Lett. 21(4), 173–174 (1972).
[CrossRef]

Jeong, Y.-C.

Jo, S. J.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Kang, D.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Kawanishi, Y.

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

Kim, H.-T.

S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
[CrossRef]

S.-J. Sung, H.-T. Kim, J.-W. Lee, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorine group,” Synth. Met. 117(1-3), 277–279 (2001).
[CrossRef]

Kim, J. B.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Kim, M.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Kim, W. S.

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

Kim, Y. S.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Kobayashi, S.

Y. Iimura, T. Saitoh, S. Kobayashi, and T. O. R. U. Hashimoto, “Liquid crystal alignment on photopolymer surfraces exposed by linearly polarized UV light,” J. Photopolym. Sci. Technol. 8(2), 257–262 (1995).
[CrossRef]

Kozinkov, V.

M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
[CrossRef]

Lee, J.

D. Ahn, Y.-C. Jeong, S. Lee, J. Lee, Y. Heo, and J.-K. Park, “Control of liquid crystal pretilt angles by using organic/inorganic hybrid interpenetrating networks,” Opt. Express 17(19), 16603–16612 (2009).
[CrossRef] [PubMed]

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

Lee, J.-W.

S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
[CrossRef]

S.-J. Sung, H.-T. Kim, J.-W. Lee, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorine group,” Synth. Met. 117(1-3), 277–279 (2001).
[CrossRef]

Lee, M. J.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Lee, S.

D. Ahn, Y.-C. Jeong, S. Lee, J. Lee, Y. Heo, and J.-K. Park, “Control of liquid crystal pretilt angles by using organic/inorganic hybrid interpenetrating networks,” Opt. Express 17(19), 16603–16612 (2009).
[CrossRef] [PubMed]

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

Lee, S. J.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Lim, J. R.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Nehring, J.

T. J. Scheffer and J. Nehring, “Accurate determination of liquid-crystal tilt bias angles,” J. Appl. Phys. 48(5), 1783–1792 (1977).
[CrossRef]

Olàh, A.

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

Owens, D. K.

D. K. Owens and R. C. Wendt, “Estimation of the surface free energy of polymers,” J. Appl. Polym. Sci. 13(8), 1741–1747 (1969).
[CrossRef]

Park, J. S.

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Park, J.-K.

D. Ahn, Y.-C. Jeong, S. Lee, J. Lee, Y. Heo, and J.-K. Park, “Control of liquid crystal pretilt angles by using organic/inorganic hybrid interpenetrating networks,” Opt. Express 17(19), 16603–16612 (2009).
[CrossRef] [PubMed]

H. Hah, S.-J. Sung, K. Y. Cho, and J.-K. Park, “Molecular orientation of liquid crystal on polymer blends of coumarin and naphthalenic polyimide,” Polym. Bull. 61(3), 383–390 (2008).
[CrossRef]

H. Hah, S.-J. Sung, and J.-K. Park, “Ultraviolet embossed alignment layer for flexible liquid crystal display,” Appl. Phys. Lett. 90(6), 063508 (2007).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

S.-J. Sung, K.-Y. Cho, and J.-K. Park, “Photo-induced liquid crystal alignment of poly(vinyl cinnamate) and fluorinated polyimide blends,” Mater. Sci. Eng. C 24(1-2), 181–184 (2004).
[CrossRef]

S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
[CrossRef]

S.-J. Sung, H.-T. Kim, J.-W. Lee, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorine group,” Synth. Met. 117(1-3), 277–279 (2001).
[CrossRef]

Saitoh, T.

Y. Iimura, T. Saitoh, S. Kobayashi, and T. O. R. U. Hashimoto, “Liquid crystal alignment on photopolymer surfraces exposed by linearly polarized UV light,” J. Photopolym. Sci. Technol. 8(2), 257–262 (1995).
[CrossRef]

Sakuragi, M.

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

Schadt, M.

M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
[CrossRef]

Scheffer, T. J.

T. J. Scheffer and J. Nehring, “Accurate determination of liquid-crystal tilt bias angles,” J. Appl. Phys. 48(5), 1783–1792 (1977).
[CrossRef]

Schmitt, K.

M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
[CrossRef]

Schönherr, H.

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

Seki, T.

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

Shannon, P.

W. Gibbons, P. Shannon, S. Sun, and B. Swetlin, “Surface-mediated alignment of nematic liquid crystals with polarized laser light,” Nature 351(6321), 49–50 (1991).
[CrossRef]

Shim, H.-K.

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

Sun, S.

W. Gibbons, P. Shannon, S. Sun, and B. Swetlin, “Surface-mediated alignment of nematic liquid crystals with polarized laser light,” Nature 351(6321), 49–50 (1991).
[CrossRef]

Sung, S.-J.

H. Hah, S.-J. Sung, K. Y. Cho, and J.-K. Park, “Molecular orientation of liquid crystal on polymer blends of coumarin and naphthalenic polyimide,” Polym. Bull. 61(3), 383–390 (2008).
[CrossRef]

H. Hah, S.-J. Sung, and J.-K. Park, “Ultraviolet embossed alignment layer for flexible liquid crystal display,” Appl. Phys. Lett. 90(6), 063508 (2007).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

S.-J. Sung, K.-Y. Cho, and J.-K. Park, “Photo-induced liquid crystal alignment of poly(vinyl cinnamate) and fluorinated polyimide blends,” Mater. Sci. Eng. C 24(1-2), 181–184 (2004).
[CrossRef]

S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
[CrossRef]

S.-J. Sung, H.-T. Kim, J.-W. Lee, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorine group,” Synth. Met. 117(1-3), 277–279 (2001).
[CrossRef]

Suzuki, Y.

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

Swetlin, B.

W. Gibbons, P. Shannon, S. Sun, and B. Swetlin, “Surface-mediated alignment of nematic liquid crystals with polarized laser light,” Nature 351(6321), 49–50 (1991).
[CrossRef]

Tamaki, T.

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

Tomczak, N.

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

Vancso, G. J.

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

Wendt, R. C.

D. K. Owens and R. C. Wendt, “Estimation of the surface free energy of polymers,” J. Appl. Polym. Sci. 13(8), 1741–1747 (1969).
[CrossRef]

Yoo, J.-H.

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

Adv. Funct. Mater. (1)

J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, “The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: liquid-crystal alignment and optical properties,” Adv. Funct. Mater. 18(8), 1340–1347 (2008).
[CrossRef]

Appl. Phys. Lett. (2)

H. Hah, S.-J. Sung, and J.-K. Park, “Ultraviolet embossed alignment layer for flexible liquid crystal display,” Appl. Phys. Lett. 90(6), 063508 (2007).
[CrossRef]

J. Janning, “Thin film surface orientation for liquid crystals,” Appl. Phys. Lett. 21(4), 173–174 (1972).
[CrossRef]

Chem. Phys. Lett. (1)

S.-J. Sung, K.-Y. Cho, J.-H. Yoo, W. S. Kim, H.-S. Chang, I. Cho, and J.-K. Park, “Dimerization behavior of cinnamate group attached to flexible polymer backbone and its effect on the molecular orientation,” Chem. Phys. Lett. 394(4-6), 238–243 (2004).
[CrossRef]

Chem. Rev. (1)

K. Ichimura, “Photoalignment of liquid-crystal systems,” Chem. Rev. 100(5), 1847–1874 (2000).
[CrossRef] [PubMed]

J. Appl. Phys. (2)

M. Schadt, K. Schmitt, V. Kozinkov, and V. Chigrinov, “Surface-induced parallel alignment of liquid crystals by linearly polymerized photopolymer,” J. Appl. Phys. 31(Part 1, No. 7), 2155–2164 (1992).
[CrossRef]

T. J. Scheffer and J. Nehring, “Accurate determination of liquid-crystal tilt bias angles,” J. Appl. Phys. 48(5), 1783–1792 (1977).
[CrossRef]

J. Appl. Polym. Sci. (1)

D. K. Owens and R. C. Wendt, “Estimation of the surface free energy of polymers,” J. Appl. Polym. Sci. 13(8), 1741–1747 (1969).
[CrossRef]

J. Photopolym. Sci. Technol. (1)

Y. Iimura, T. Saitoh, S. Kobayashi, and T. O. R. U. Hashimoto, “Liquid crystal alignment on photopolymer surfraces exposed by linearly polarized UV light,” J. Photopolym. Sci. Technol. 8(2), 257–262 (1995).
[CrossRef]

Jpn. J. Appl. Phys. (1)

S.-J. Sung, K.-Y. Cho, H. Hah, S. Lee, and J.-K. Park, “Effect of plasticization of poly(vinyl cinnamate) on liquid crystal orientation stability,” Jpn. J. Appl. Phys. 44(13), L412–L415 (2005).
[CrossRef]

Langmuir (3)

H. Hillborg, N. Tomczak, A. Olàh, H. Schönherr, and G. J. Vancso, “Nanoscale hydrophobic recovery: A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane),” Langmuir 20(3), 785–794 (2004).
[CrossRef] [PubMed]

Y. Kawanishi, T. Tamaki, M. Sakuragi, T. Seki, Y. Suzuki, and K. Ichimura, “Photochemical induction and modulation of nematic homogeneous alignment by the polarization photochromism of surface azobenzenes,” Langmuir 8(11), 2601–2604 (1992).
[CrossRef]

K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, ““Reversible change in alignment mode of nematic liquid crystals regulated photochemically by “Command Surface” modified with an azobenzene monolayer,” Langmuir 4(5), 1214–1216 (1988).
[CrossRef]

Liq. Cryst. (2)

S.-J. Sung, J. Lee, K.-Y. Cho, W. S. Kim, H. Hah, H.-K. Shim, and J.-K. Park, “Effect of photoreactivity of polyimide on the molecular orientation of liquid crystals on photoreactive polymer/polyimide blends,” Liq. Cryst. 31(12), 1601–1611 (2004).
[CrossRef]

S.-J. Sung, J.-W. Lee, H.-T. Kim, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorinated groups,” Liq. Cryst. 29(2), 243–250 (2002).
[CrossRef]

Mater. Sci. Eng. C (1)

S.-J. Sung, K.-Y. Cho, and J.-K. Park, “Photo-induced liquid crystal alignment of poly(vinyl cinnamate) and fluorinated polyimide blends,” Mater. Sci. Eng. C 24(1-2), 181–184 (2004).
[CrossRef]

Nature (1)

W. Gibbons, P. Shannon, S. Sun, and B. Swetlin, “Surface-mediated alignment of nematic liquid crystals with polarized laser light,” Nature 351(6321), 49–50 (1991).
[CrossRef]

Opt. Express (1)

Polym. Bull. (1)

H. Hah, S.-J. Sung, K. Y. Cho, and J.-K. Park, “Molecular orientation of liquid crystal on polymer blends of coumarin and naphthalenic polyimide,” Polym. Bull. 61(3), 383–390 (2008).
[CrossRef]

Polymer (Guildf.) (1)

S.-J. Sung, K.-Y. Cho, H. Hah, J. Lee, H.-K. Shim, and J.-K. Park, “Two different reaction mechanisms of cinnamate side groups attached to the various polymer backbones,” Polymer (Guildf.) 47(7), 2314–2321 (2006).
[CrossRef]

Synth. Met. (1)

S.-J. Sung, H.-T. Kim, J.-W. Lee, and J.-K. Park, “Photo-induced liquid crystal alignment on polyimide containing fluorine group,” Synth. Met. 117(1-3), 277–279 (2001).
[CrossRef]

Other (2)

A. J. Kinloch, Adhesion and adhesives: science and technology (Chapman and Hall, 1987).

K. Takatoh, M. Hasegawa, M. Koden, N. Itoh, R. Hasegawa, and M. Sakamoto, “Rubbing Technologies: Mechanisms and Applications,” in Alignment Technologies and Applications of Liquid Crystal Devices (Taylor & Francis, 2007), pp.7–8.

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Figures (10)

Fig. 1
Fig. 1

(a) Molecular structure of photoreactive 2Ci-BD oligomer. (b) 1H NMR spectrum of 2Ci-BD oligomer in CDCl3.

Fig. 2
Fig. 2

Schematic illustration of procedures for fabricating alignment layer to generate pretilt angle.

Fig. 3
Fig. 3

Digital photograph of experimental setup for a directional peel-off process.

Fig. 4
Fig. 4

Contact angles of PDMS layer as a function of time of UVO treatment. The inset images represent the water droplet shapes on the PDMS surface.

Fig. 5
Fig. 5

Pretilt angles of photo-reactive oligomer (2Ci-BD) layer and polymer (PVCi) layer with respect to the time of UVO treatment of PDMS film.

Fig. 6
Fig. 6

Ratio of work of adhesion between three different surfaces (Surface 1: HDMS treated glass substrate, surface 2: photo-aligned 2Ci-BD oligomer layer, and surface 3: PDMS film without and with UVO treatment) as a function of time of UVO treatment. The ratio of work of adhesion can be defined by R = W23∙A23/W12∙A12 [23]. Since A23 and A12 have the same values, R can be simply expressed as the ratio of W23 to W12..

Fig. 7
Fig. 7

ATR-FTIR spectra of PDMS film with respect to the time of UVO treatment of PDMS after a directional peel-off process: (a) in the wavelength range of 3000–930 cm−1 and (b) in the wavelength range of 1800–1650 cm−1.

Fig. 8
Fig. 8

Polar plot of liquid crystal orientation on the alignment layer of 2Ci-BD: (a) before the directional peel-off process and (b) after the directional peel-off process.

Fig. 9
Fig. 9

DSC thermograms of 2Ci-BD oligomer scanned at a heating rate of 10°C/min.

Fig. 10
Fig. 10

Polarized optical microscopic images of liquid crystal cell prepared with 2Ci-BD oligomer after a directional peel-off process. The directions of polarizers (A and P) and the photoalignment direction of liquid crystals are denoted as arrows in the images.

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