Photodeformable Materials and Photomechanical Effects Based on Azobenzene-Containing Polymers and Liquid Crystals

Smart Light-Responsive Materials: Azobenzene-Containing Polymers and Liquid Crystals

Volumn , Issue , 2008, Pages 95-144

  Yu, Yanlei ^a   Ikeda, Tomiki ^b  

^a FUDAN UNIVERSITY   (China)

^b TOKYO INSTITUTE OF TECHNOLOGY   (Japan)

Author keywords

Photodeformable materials and photomechanical effects; Photodeformable materials based on azobenzene containing polymer gels; Photoresponsive behavior of chromophore containing LCs

Indexed keywords

EID: 84889304382     PISSN: None     EISSN: None     Source Type: Book    
DOI: 10.1002/9780470439098.ch3     Document Type: Chapter

References (150)

1. Barnes NR, Davis FJ, Mitchell GR. 1989. Molecular switching in liquid crystal elastomers. Mol Cryst Liq Cryst 168:13-25.
2. Baughman RH. 1996. Conducting polymer artificial muscles. Synth Met 78:339-353.
3. Baughman RH, Cui C, Zakhidov AA, Iqbal Z, Barisci JN, Spinks GM, Wallace GG, Mazzoldi A, De Rossi D, Rinzler AG, Jaschinski O, Roth S, Kertesz M. 1999. Carbon nanotube actuators. Science 284:1340-1343.
4. Bay L, West K, Sommer-Larsen P, Skaarup S, Benslimane M. 2003. A conducting polymer artificial muscle with 12% linear strain. Adv Mater 15:310-313.
5. Beyer P, Zentel R. 2005. Photoswitchable smectic liquid-crystalline elastomers. Macromol Rapid Commun 26:874-879.
6. Brand HR, Finkelmann H. 1998. Physical properties of liquid crystalline elastomers. In: Handbook of liquid crystals. Demus D, Goodby J. Gray GW, Spiess HW, Vill V, editors. Weinheim: Wiley-VCH.
7. Brehmer M, Zentel R. 1994. Ferroelectric liquid-crystalline elastomers. Macromol Chem Phys 195:1891-1904.
8. Brodowsky HM, Boehnke UC, Kremer F, Gebhard E, Zentel R. 1999. Mechanical deformation behavior in highly anisotropic elastomers made from ferroelectric liquid crystalline polymers. Langmuir 15:274-278.
9. Broer DJ, Finkelmann H, Kondo K. 1988. In-situ photopolymerization of an oriented liquid-crystalline acrylate. Makromol Chem 189:185-194.
10. Broer DJ, Boven J, Mol GN, Challa G. 1989. In-situ photopolymerization of oriented liquid-crystalline acrylates. Makromol Chem 190:2255-2268.
11. Buguin A, Li MH, Silberzan P, Ladoux B, Keller P. 2006. Micro-actuators: when artificial muscles made of nematic liquid crystal elastomers meet soft lithography. J Am Chem Soc 128:1088-1089.
12. Camacho-Lopez M, Finkelmann H, Palffy-Muhoray P, Shelley M. 2004. Fast liquid-crystal elastomer swims into the dark. Nat Mater 3:307-310.
13. Clarke SM, Hotta A, Tajbakhsh AR, Terentjev EM, 2001. Effect of cross-linker geometry on equilibrium thermal and mechanical properties of nematic elastomers. Phys Rev E 64:061702.
14. Cotton JP, Hardouin F. 1997. Chain conforation of liquid-crystalline polymers studied by small-angle neutron scattering. Prog Polym Sci 22:795-828.
15. Courty S, Mine J, Tajbakhsh AR, Terentjev EM. 2003. Nematic elastomers with aligned carbon nanotubes: new electromechanical actuators. Europhys Lett 64:654-660.
16. Cui L, Zhao Y. 2004. Azopyridine side chain polymers: an efficient way to prepare photoactive liquid crystalline materials through self-assembly. Chem Mater 16:20762082.
17. Cui L, Tong X, Yan X, Liu G, Zhao Y. 2004. Photoactive thermoplastic elastomers of azobenzene-containing triblock copolymers prepared through atom transfer radical polymerization. Macromolecules 37:7097-7104.
18. Cviklinski J, Tajbakhsh AR, Terentjev EM. 2002. UV isomerisation in nematic elastomers as a route to photo-mechanical transducer. Eur Phys J E 9:427-434.
19. De Gennes PG. 1975. Physique moleculaire. C R Acad Sci B 281:101-103.
20. Disch S, Finkelmann H, Ringsdorf H, Schuhmacher P. 1995. Macroscopically ordered discotic columnar networks. Macromolecules 28:2424-2428.
21. Eich M, Wendorff JH. 1987. Erasable holograms in polymeric liquid crystals. Makromol Chem Rapid Commun 8:467-471.
22. Eich M, Wendorff JH, Reck B, Ringsdorf H. 1987. Reversible digital and holographic optical storage in polymeric liquid crystals. Makromol Chem Rapid Commun 8:59-63.
23. Eisenbach CD. 1980. Isomerization of aromatic azo chromophores in poly(ethyl acrylate) networks and photomechanical effect. Polymer 21:1175-1179.
24. Finkelmann H, Nishikawa E. 2001. A new opto-mechanical effect in solids. Phys Rev Lett 87:015501.
25. Finkelmann H, Rehage G. 1984. The degree of order in liquid crystalline side chain polymers. Adv Polym Sci 60/61:99-172.
26. Finkelmann H, Kock HJ, Rehage G. 1981. Investigations on liquid crystalline polysilox-anes, 3. Liquid crystalline elastomers-a new type of liquid crystalline material. Makromol Chem Rapid Commun 2:317-322.
27. Finkelmann H, Kim ST, Muñoz A, Palffy-Muhoray P, Taheri B. 2001. Tunable mirrorless lasing in cholesteric liquid crystalline elastomers. Adv Mater 13:1069-1072.
28. Fukuda A, Takezoe H. 1990. Structures and Properties of Ferroelectric Liquid Crystals. Tokyo: Corona.
29. Fukushima T, Asaka K, Kosaka A, Aida T. 2005. Fully plastic actuator through layer-by-layer casting with ionic-liquid-based bucky gel.Angew Chem Int Ed Engl 44:2410-2413.
30. Gao J, Sansiñena JM, Wang HL. 2003. Tunable polyaniline chemical actuators. Chem Mater 15:2411-2418.
31. Gebhard E, Zentel R. 1998. Freestanding ferroelectric elastomer films. Macromol Rapid Commun 19:341-344.
32. Harris KD, Bastlaansen CWM, Lub J, Broer DJ. 2005a. Self-assembled polymer films for controlled agent-driven motion. Nano Lett 5:1857-1860.
33. Harris KD, Cuypers R, Sscheibe P, Van Oosten CL, Bastiaansen CWM, Lub J, Broer DJ. 2005b. Large amplitude light-induced motion in high elastic modulus polymer actuators. J Mater Chem 15:5043-5048.
34. He XZ, Zhang BY, Meng FB, Lin JR. 2005. Effect of the length of the carbochain on the phase behavior of side-chain cholesteric liquid-crystalline elastomers. J Appl Polym Sci 96:1204-1210.
35. Hiraoka K, Sagano W, Nose T, Finkelmann H. 2005. Biaxial shape memory effect exhibited by monodomain chiral smectic C elastomers. Macromolecules 38:7352-7357.
36. Hogan PM, Tajbakhsh AR, Terentjev EM. 2002. UV manipulation of order and macroscopic shape in nematic elastomers. Phys Rev E 65:041720.
37. Holland NB, Hugel T, Neuert G, Cattani-Scholz A, Renner C, Oesterhelt D, Moroder L, Seitz M, Gaub HE. 2003. Single molecule force spectroscopy of azobenzene polymers: switching elasticity of single photochromic macromolecules. Macromolecules 36:20152023.
38. Hosono N, Furukawa H, Masubuchi Y, Watanabe T, Horie K. 2007. Photochemical control of network structure in gels and photo-induced changes in their viscoelastic properties. Colloids Surf B Biointerfaces 56:285-289.
39. Hu Z, Zhang X, Li Y. 1995. Monitoring release of neurotrophic activity in the brains of awake rats. Science 269:525-553.
40. Hugel T, Holland NB, Cattani A, Moroder L, Seitz M, Gaub HE. 2002. Single-molecule optomechanical cycle. Science 296:1103-1106.
41. Ikeda T. 2001. Photochemical modulation of refractive index by means of photosensitive liquid crystals. Mol Cryst Liq Cryst 364:187-197.
42. Ikeda T. 2003. Photomodulation of liquid crystal orientations for photonic applications. J Mater Chem 13:2037-2057.
43. Ikeda T, Tsutsumi O. 1995. Optical switching and image storage by means of azobenzene liquid-crystal films. Science 268:1873-1875.
44. Ikeda T, Horiuchi S, Karanjit DB, Kurihara S, Tazuke S. 1988. Photochemical image storage in polymer liquid crystals. Chem Lett 17:1679-1682.
45. Ikeda T, Horiuchi S, Karanjit DB, Kurihara S, Tazuke S. 1990a. Photochemically induced isothermal phase transition in polymer liquid crystals with mesogenic phenyl benzoate side chains. 1. Calorimetric studies and order parameters. Macromolecules 23:36-42.
46. Ikeda T, Horiuchi S, Karanjit DB, Kurihara S, Tazuke S. 1990b. Photochemically induced isothermal phase transition in polymer liquid crystals with mesogenic phenyl benzoate side chains. 2. Photochemically induced isothermal phase transition behaviors. Macromolecules 23:42-48.
47. Ikeda T, Horiuchi S, Karanjit DB, Kurihara S, Tazuke S. 1990c. Photochemically induced isothermal phase transition in polymer liquid crystals with mesogenic cyanobiphenyl side chains. Macromolecules 23:3938-3943.
48. Ikeda T, Sasaki T, Kim HB. 1991. "Intrinsic" response of polymer liquid crystals in photochemical phase transition. J Phys Chem 95:509-511.
49. Ikeda T, Sasaki T, Ichimura K. 1993. Photochemical switching of polarizationin ferroelectric liquid-crystal films. Nature 361:428-430.
50. Ikeda T, Nakano M, Yu Y, Tsutsumi O, Kanazawa A. 2003. Anisotropic bending and unbending behavior of azobenzene liquid-crystalline gels by light exposure. Adv Mater 15:201-205.
51. Irie M. 1986. Photoresponsive polymer. Reversible bending of rod-shaped acrylamide gels in an electric field. Macromolecules 19:2890-2892.
52. Irie M. 1990. Photoresponsive polymers. Adv Polym Sci 94:27-67.
53. Irie M, Kungwatchakun D. 1995. Photoresponsive polymer. Mechanochemistry of polyacrylamide gels having triphenylmethane leuco derivatives. Makromol Chem Rapid Commun 5:829-832.
54. Ishikawa M, Kitamura N, Masuhara H, Irie M. 1991. Size effect on photoinduced volume change of polyacrylamide microgels containing triphenylmethane leuco cyanide. Mak-romol Chem Rapid Commun 12:687-690.
55. Jager EWH, Smela E, Inganas O. 2000. Microfabricating conjugated polymer actuators. Science 290:1540-1545.
56. Kelly SM. 1995. Anisotropic networks. J Mater Chem 5:2047-2061.
57. Kim HK, Wang XS, Fujita Y, Sudo A, Nishida H, Fujii M, Endo T. 2005a. Photomechanical switching behavior of semi-interpenetrating polymer network consisting of azobenzene-carrying crosslinked poly(vinyl ether) and polycarbonate. Macromol Rapid Commun 26:1032-1036.
58. Kim HK, Wang XS, Fujita Y, Sudo A, Nishida H, Fujii M, Endo T. 2005b. Reversible photo-mechanical switching behavior of azobenzene-containing semi-interpenetrating network under UV and visible light irradiation. Macromol Chem Phys 206:2106-2111.
59. Kim HK, Wang XS, Fujita Y, Sudo A, Nishida H, Fujii M, Endo T. 2005c. A rapid photomechanical switching polymer blend system composed of azobenzene-carrying poly(vinylether) and poly(carbonate). Polymer 46:5879-5883.
60. Kim P, Lieber CM. 1999. Nanotube nanotweezers. Science 286:2148-2150.
61. Kishi R, Suzuki Y, Ichijo H, Hirasa O. 1994. Electrical deformation of thermotropic liquid-crystalline polymer gels. Chem Lett 2257-2260.
62. Kondo M, Yu Y, Ikeda T. 2006. How does the initial alignment of mesogens affect the photoinduced bending behavior of liquid-crystalline elastomers. 2006. Angew Chem Int Ed Engl 45:1378-1382.
63. Kondo M, Yu Y, Mamiya J, Kinoshita M, Ikeda T. 2007. Photoinduced deformation behavior of crosslinked azobenzene liquid-crystalline polymer films with unimorph and bimorph structure. Mol Cryst Liq Cryst 478:245-257.
64. Kumar A, Srivastava A, Galaev IY, Mattiasson B. 2007. Smart polymers: physical forms & bioengineering applications. Prog Polym Sci 32:1205-1237.
65. Kundler I, Finkelmann H. 1998. Director reorientation via stripe-domains in nematic elastomers: influence of cross-link density, anisotropy of the network and smectic clusters. Macromol Chem Phys 199:677-686.
66. Küpfer J, Finkelmann H. 1991. Nematic liquid single crystal elastomers. Makromol Chem Rapid Commun 12:717-726.
67. Küpfer J, Finkelmann H. 1994. Liquid crystal elastomers: influence of the orientational distribution of the crosslink's on the phase behaviour and reorientation processes. Macromol Chem Phys 195:1353-1367.
68. Küpfer J, Nishikawa E, Finkelmann H. 1994. Densely crosslinked liquid single-crystal elastomers. Polym Adv Technol 5:110-115.
69. Kurihara S, Ikeda T, Sasaki T, Kim HB, Tazuke S. 1990. Time-resolved observation of isothermal phase transition of liquid crystals triggered by photochemical reaction of dopant. J Chem Soc Chem Commun 1751-1752.
70. Legge CH, Mitchell GR. 1992. Photo-induced phase transitions in azobenzene-doped liquid crystals. J Phys D: Appl Phys 25:492-494.
71. Lehmann W, Skupin H, Tolksdorf C, Gebhard E, Zentel R, Krüger P, Lösche M, Kremer F. 2001. Giant lateral electrostriction in ferroelectric liquid-crystalline elastomers. Nature 410:447-450.
72. Lendlein A, Jiang H, Jünger O, Langer R. 2005. Light-induced shape-memory polymers. Nature 434:879-882.
73. Li MH, Keller P, Li B, Wang X, Brunet M. 2003. Light-driven side-on nematic elastomer actuators. Adv Mater 15:569-572.
74. Li MH, Keller P, Yang J, Albouy PA. 2004. An artificial muscle with lamellar structure based on a nematic triblock copolymer. Adv Mater 16:1922-1925.
75. Liu C, Chun BS, Mather PT, Zheng L, Haley EH, Coughlin EB. 2002. Chemically crosslinked polycyclooctene: synthesis, characterization, and shape memory behavior. Macromolecules 35:9868-9874.
76. Liu Z, Calver P. 2000. Multilayer hydrogels as muscle-like actuators. Adv Mater 12: 288-291.
77. Mamada A, Tanaka T, Kungwatchakun D, Irie M. 1990. Photoinduced phase transition of gels. Macromolecules 23:1517-1519.
78. Mamiya J, Yoshitake A, Kondo M, Yu Y, Ikeda T. 2008. Is chemical crosslinking necessary for the photoinduced bending of polymer films? J Mater Chem 18:63-65.
79. Mao Y, Terentjev EM, Warner M. 2001. Cholesteric elastomers: deformable photonic solids. Phys Rev E 64:041803.
80. Matějka L, Dusek K. 1981. Photochromic polymers: photoinduced conformational changes and effect of polymeric matrix on the isomerization of photochromes. Makromol Chem 182:3223-3236.
81. Matějka L, Dušek K, Iiavský M. 1979. The thermal effect in the photomechanical conversion of a photochromic polymer. Polym Bull 1:659-664.
82. Matějka L, Ilavský M, Dusek K, Wichterle O. 1981. Photomechanical effects in crosslinked photochromic polymers. Polymer 22:1511-1515.
83. Meng FB, Zhang BY, Xiao WQ, Hu TX. 2005. Effect of nonmesogenic crosslinking units on the mesogenic properties of side-chain cholesteric liquid crystalline elastomers. J Appl Polym Sci 96:625-631.
84. Merian E. 1966. Steric factors influencing the dyeing of hydrophobic fibers. Textile Res J 36:612-618.
85. Mol GN, Harris KD, Bastiaansen CM, Broer DJ. 2005. Thermo-mechanical responses of liquid-crystal networks with a splayed molecular organization. Adv Funct Mater 15:1155-1159.
86. Moriyama T, Kajita J, Takanashi Y, Ishikawa K, Takezoe H, Fukuda A. 1993. Optically addressed spatial light modulator using an antiferroelectric liquid crystal doped with azobenzene. Jpn J Appl Phys 32:L589-L592.
87. Mun-Sik K, Vinay KG. 2002. Photochromic cross-links in thermoresponsive hydrogels of poly(N-isopropylacrylamide): enthalpic and entropic consequences on swelling behavior. J Phys Chem B 106:4127-4132.
88. Naciri J, Srinivasan A, Jeon H, Nikolov N, Keller P, Ratna BR. 2003. Nematic elastomer fiber actuator. Macromolecules 36:8499-8505.
89. Natansohn A, Rochon P. 2002. Photoinduced motions in azo-containing polymers. Chem Rev 102:4139-4175.
90. Negishi M, Tsutsumi O, Ikeda T, Hiyama T, Kawamura J, Aizawa M, Takehara S. 1996a. Photochemical switching of ferroelectric liquid crystals using a photoswitchable chiral dopant. Chem Lett 25:319-320.
91. Negishi M, Kanie K, Ikeda T, Hiyama T. 1996b. Synthesis and photochemical switching of the antiferroelectric liquid crystals containing a diazenediyl group. Chem Lett 25:583-584.
92. Nishikawa E, Finkelmann H. 1997. Orientation behavior of smectic polymer networks by uniaxial mechanical fields. Macromol Chem Phys 198:2531-2549.
93. Nishikawa E, Finkelmann H. 1999. Smectic-A liquid single crystal elastomers-strain induced break-down of smectic layers. Macromol Chem Phys 200:312-322.
94. Osada Y, Gong JP. 1998. Soft and wet materials: polymer gels. Adv Mater 10:827-837.
95. Osada Y, Okuzaki H, Hori H. 1992. A polymer gel with electrically driven motility. Nature 355:242-243.
96. Otero TF, Cortes MT. 2003. Artifical muscles with tactile sensitivity. Adv Mater 15: 279-282.
97. Pelrine R, Kornbluh R, Pei Q, Joseph J. 2000. High-speed electrically actuated elastomers with strain greater than 100%. Science 287:836-838.
98. Saikrasun S, Bualek-Limcharoen S, Kohjiya S, Urayama K. 2005. Anisotropic mechanical properties of thermoplastic elastomers in situ reinforced with thermotropic liquid-crystalline polymer fibers revealed by biaxial deformations. J Polym Sci Part B: Polym Phys 43:135-144.
99. Sakai T, Murayama H, Nagano S, Takeoka Y, Kidowaki M, Ito K, Seki T. 2007. Photoresponsive slide-ring gel. Adv Mater 19:2023-2025.
100. Sanchez C, Villacampa B, Alcala R, Martinez C, Oriol L, Pinol M, Serrano JM. 1999. Mesomorphic and orientational study of materials processed by in situ photopolymerization of reactive liquid crystals. Chem Mater 11:2804-2812.
101. Sasaki T, Ikeda T. 1993. Photochemical switching of polarization in ferroelectric liquid crystals: effect of structure of host FLCs. Ferroelectrics 149:343-351.
102. Sasaki T, Ikeda T. 1995a. Photochemical control of properties of ferroelectric liquid crystals. 1. Effect of structure of host ferroelectric liquid crystals on the photochemical switching of polarization. J Phys Chem 99:13002-13007.
103. Sasaki T, Ikeda T. 1995b. Photochemical control of properties of ferroelectric liquid crystals. 2. Effect of the structure of guest photoresponsive molecules on the photochemical switching of polarization. J Phys Chem 99:13008-13012.
104. Sasaki T, Ikeda T. 1995c. Photochemical control of properties of ferroelectric liquid crystals. 3. Photochemically induced reversible change in spontaneous polarization and electrooptic property. J Phys Chem 99:13013-13018.
105. Sasaki T, Ikeda T, Ichimura K. 1992. Time-resolved observation of photochemical phase transition in polymer liquid crystals. Macromolecules 25:3807-3811.
106. Sasaki T, Ikeda T, Ichimura K. 1994. Photochemical control of properties of ferroelectric liquid crystals: photochemical flip of polarization. J Am Chem Soc 116:625-628.
107. Shandryuk GA, Kuptsov SA, Shatalova AM, Plate NA, Talroze RV. 2003. Liquid crystal H-bonded polymer networks under mechanical stress. Macromolecules 36:3417-3423.
108. A-SmC* phase transition. Jpn J Appl Phys 36:L1035-L1037.
109. Smela E. 2003. Conjugated polymer actuators for biomedical applications. Adv Mater 15:481-494.
110. Smets G, De Blauwe F. 1974. Chemical reaction in solid polymeric systems. Photomechanical phenomena. Pure Appl Chem 39:225-238.
111. Spinks GM, Wallace GG, Fifield LS, Dalton LR, Mazzoldi A, De Rossi D, Khayrullin II, Baughman RH. 2002. Pneumatic carbon nanotube actuators. Adv Mater 14:1728-1732.
112. Stenull O, Lubensky TC. 2005. Phase transitions and soft elasticity of smectic elastomers. Phys Rev Lett 94:018304.
113. Sung JH, Hirano S, Tsutsumi O, Kanazawa A, Shiono T, Ikeda T. 2002. Dynamics of photochemical phase transition of guest/host liquid crystals with an azobenzene derivative as a photosensitive chromophore. Chem Mater 14:385-391.
114. Suzuki A, Tanaka T. 1990. Phase transition in polymer gels induced by visible light. Nature 346:345-347.
115. Suzuki A, Ishii T, Maruyama Y. 1996. Optical switching in polymer gels. J Appl Phys 80:131-136.
116. Tabiryan N, Serak S, Dai XM, Bunning T. 2005. Polymer film with optically controlled form and actuation. Opt Express 13:7442-7448.
117. Tammer M, Li J, Komp A, Finkelmann H, Kremer F. 2005. FTIR-spectroscopy on segmental reorientation of a nematic elastomer under external mechanical fields. Macromol Chem Phys 206:709-714.
118. Tanchak OM, Barrett CJ. 2005. Light-induced reversible volume changes in thin films of azo polymers: the photomechanical effect. Macromolecules 38:10566-10570.
119. Tazuke S, Kurihara S, Ikeda T. 1987. Amplified image recording in liquid crystal media by means of photochemically triggered phase transition. Chem Lett 16:911-914.
120. Terentjev EM. 1999. Liquid-crystalline elastomers. J Phys Condens Matter 11:R239-R257.
121. Thomsen DL, Keller P, Naciri J, Pink R, Jeon H, Shenoy D, Ratna BR. 2001. Liquid crystal elastomers with mechanical properties of a muscle. Macromolecules 34: 5868-5875.
122. Tsutsumi O, Shiono T, Ikeda T, Galli G. 1997. Photochemical phase transition behavior of nematic liquid crystals with azobenzene moieties as both mesogens and photosensitive chromophores. J Phys Chem B 101:1332-1337.
123. Tsutsumi O, Demachi Y, Kanazawa A, Shiono T, Ikeda T, Nagase Y. 1998a. Photochemical phase-transition behavior of polymer liquid crystals induced by photochemical reaction of azobenzenes with strong donor-acceptor pairs. J Phys Chem B 102:2869-2874.
124. Tsutsumi O, Kitsunai T, Kanazawa A, Shiono T, Ikeda T. 1998b. Photochemical phase transition behavior of polymer azobenzene liquid crystals with electron-donating and accepting substituents at 4,4'-positions. Macromolecules 31:355-359.
125. Van der Veen G, Prins W. 1971. Photomechanical energy conversion in a polymer membrane. Nature Phys Sci 230:70-72.
126. Van der Veen G, Prins W. 1974. Photoregulation of polymer conformation by photo-chromic moieties-I. Anionic ligand to an anionic polymer. Photochem Photobiol 19:191-196.
127. Van der Veen G, Noguet R, Prins W. 1974. Photoregulation of polymer conformation by photochromic moieties-II. Cationic and neutral moieties of an anionic polymer. Photochem Photobiol 19:197-204.
128. Warner M, Terentjev EM. 1996. Nematic elastomers-a new state of mater. Prog Polym Sci 21:853-891.
129. Warner M, Terentjev EM. 2003. Liquid Crystal Elastomers. UK: Oxford University.
130. Warner M, Gelling KP, Vilgis TA. 1988. Theory of nematic networks. J Chem Phys 88:4008-4013.
131. Wermter H, Finkelmann H. 2001. Liquid crystalline elastomers as artificial muscles. e-Polymer 013:1-13.
132. Xie P, Zhang R. 2005. Liquid crystal elastomers, networks and gels: advanced smart materials. J Mater Chem 15:2529-2550.
133. Yamada M, Kondo M, Mamiya J, Yu Y, Kinoshita M, Barrett CJ, Ikeda T. 2008. Photomobile polymer materials-towards light-driven plastic motors. Angew Chem Int Ed Engl 47:4986-4988.
134. Yoshida R, Uchida K, Kaneko Y, Sakai K, Kikuchi A, Sakuraui Y, Okano T. 1995. Comb-type grafted hydrogels with rapid de-swelling response to temperature changes. Nature 374:240-242.
135. Yu Y, Nakano M, Ikeda T. 2003. Directed bending of a polymer film by light. Nature 425:145.
136. Yu Y, Nakano M, Ikeda T. 2004a. Photoinduced bending and unbending behavior of liquid-crystalline gels and elastomers. Pure Appl Chem 76:1435-1445.
137. Yu Y, Nakano M, Shishido A, Shiono T, Ikeda T. 2004b. Effect of cross-linking density on photoinduced bending behavior of oriented liquid-crystalline network films containing azobenzene. Chem Mater 16:1637-1643.
138. Yu Y, Maeda T, Mamiya J, Ikeda T. 2007. Photomechanical effects of ferroelectric liquid-crystalline elastomers containing azobenzene chromophores. Angew Chem Int Ed Engl 46:881-883.
139. Yusuf Y, Sumisaki Y, Kai S. 2003. Birefringence measurement of liquid single crystal elastomer swollen with low molecular weight liquid crystal. Chem Phys Lett 382:198-202.
140. Yusuf Y, Cladis PE, Brand HR, Finkelmann H, Kai S. 2004a. Hystereses of volume changes in liquid single crystal elastomers swollen with low molecular weight liquid crystal. Chem Phys Lett 389:443-448.
141. Yusuf Y, Ono Y, Sumisaki Y, Cladis PE, Brand HR, Finkelmann H, Kai S. 2004b. Swelling dynamics of liquid crystal elastomers swollen with low molecular weight liquid crystals. Phys Rev E 69:021710.
142. Yusuf Y, Huh JH, Cladis PE, Brand HR, Finkelmann H, Kai S. 2005. Low-voltage-driven electromechanical effects of swollen liquid-crystal elastomers. Phy Rev E 71:061702.
143. Zanna JJ, Stein P, Marty JD, Mauzac M, Martinoty P. 2002. Influence of molecular parameters on the elastic and viscoelastic properties of side-chain liquid crystalline elastomers. Macromolecules 35:5459-5465.
144. Zentel R. 1986. Shape variation of cross-linked liquid-crystalline polymers by electric fields. Liq Cryst 1:589-592.
145. Zentel R. 1989. Liquid crystalline elastomers. Adv Mater 10:321-329.
146. Zentel R, Reckert G. 1986. Liquid crystalline elastomers based on liquid crystalline side group, main chain and combined polymers. Makromol Chem 187:1915-1926.
147. Zentel R, Benalia M. 1987. Stress-induced orientation in lightly crosslinked liquid-crystalline side-group polymers. Makromol Chem 188:665-674.
148. Zhang X, Li Y, Hu Z, Litter CL. 1995. Bending of N-isopropylacrylamide gel under the influence of infrared light. J Chem Phys 102:551-555.
149. Zhang Y, Iijima S. 1999. Elastic response of carbon nanotube bundles to visible light. Phys Rev Lett 82:3472-3475.
150. Zriny M, Feher J, Filipcsei G. 2000. Novel gel actuator containing TiO2 particles operated under static electric field. Macromolecules 33:5751-5753.