Simultaneous analysis of optical and mechanical properties of cross-linked azobenzene-containing liquid-crystalline polymer films.

The photomechanical behavior of cross-linked azobenzene-containing liquid-crystalline polymer films was investigated by means of simultaneous measurement of their optical and mechanical properties. The connection between photoisomerization of the azobenzene moieties, photoinduced change in molecular alignment, photoinduced stress generation, and macroscopic bending was analyzed. Upon UV irradiation, the films exhibited bending due to gradient in cis-azobenzene content, and subsequent unbending when cis-azobenzene content became uniform throughout the film. The maximum photoinduced stress was generated in the same time scale as the time required to reach photostationary state in the cis-azobenzene concentration. The maximum values of photogenerated stress strongly depended on the crosslinker concentration, even if the azobenzene concentration and the cis-azobenzene content in the photostationary state were similar for all the polymer films. The stress is connected to the initial Young's modulus and also to the photoinduced change in birefringence of the polymer films. In addition, a significant photoinduced decrease in Young's modulus was for the first time observed in cross-linked azobenzene-containing liquid-crystalline polymers, which is likely to be an important factor in dictating their photomechanical behavior.

[1]  T. Ikeda,et al.  Photoresponsive Behavior of Crosslinked Liquid-Crystalline Polymer Films with a Different Content of an Azobenzene Moiety , 2010 .

[2]  Richard A. Vaia,et al.  Relationship between the Photomechanical Response and the Thermomechanical Properties of Azobenzene Liquid Crystalline Polymer Networks , 2010 .

[3]  Yanlei Yu,et al.  Photoinduced bending behavior of crosslinked liquid-crystalline polymer films with a long spacer , 2010 .

[4]  Yanlei Yu,et al.  Fully plastic microrobots which manipulate objects using only visible light , 2010 .

[5]  Yanlei Yu,et al.  Three‐Dimensional Photomobility of Crosslinked Azobenzene Liquid‐Crystalline Polymer Fibers , 2010, Advanced materials.

[6]  Nelson V. Tabiryan,et al.  Liquid crystalline polymer cantilever oscillators fueled by light , 2010 .

[7]  M. Sugimoto,et al.  Effect of concentration of photoactive chromophores on photomechanical properties of crosslinked azobenzene liquid-crystalline polymers , 2010 .

[8]  T. Ikeda,et al.  Photomechanical properties of azobenzene liquid-crystalline elastomers , 2009 .

[9]  D. Broer,et al.  Printed artificial cilia from liquid-crystal network actuators modularly driven by light. , 2009, Nature materials.

[10]  T. Ikeda,et al.  Photomobile polymer materials—various three-dimensional movements , 2009 .

[11]  M. Warner,et al.  Polarization dependence of optically driven polydomain elastomer mechanics. , 2008, Physical review. E, Statistical, nonlinear, and soft matter physics.

[12]  Cees W. M. Bastiaansen,et al.  Bending Dynamics and Directionality Reversal in Liquid Crystal Network Photoactuators , 2008 .

[13]  R. Vaia,et al.  A high frequency photodriven polymer oscillator , 2008 .

[14]  T. Ikeda,et al.  Photomobile polymer materials: towards light-driven plastic motors. , 2008, Angewandte Chemie.

[15]  M. Nowicki,et al.  A Nanoindentation Study of Photo-Induced Changes in Polymers Containing Azobenzene , 2008 .

[16]  Martin L. Dunn,et al.  Photomechanics of mono- and polydomain liquid crystal elastomer films , 2007 .

[17]  E. Terentjev,et al.  Role of polarization and alignment in photoactuation of nematic elastomers , 2007, The European physical journal. E, Soft matter.

[18]  Yanlei Yu,et al.  Photomechanical effects of ferroelectric liquid-crystalline elastomers containing azobenzene chromophores. , 2007, Angewandte Chemie.

[19]  Yanlei Yu,et al.  Photomechanics of liquid-crystalline elastomers and other polymers. , 2007, Angewandte Chemie.

[20]  H. Finkelmann,et al.  A new type of macroscopically oriented smectic-A liquid crystal elastomer , 2007 .

[21]  Marina Saphiannikova,et al.  Molecular tracer diffusion in thin azobenzene polymer layers , 2006 .

[22]  Kevin G. Yager,et al.  Photomechanical Surface Patterning in Azo-Polymer Materials , 2006 .

[23]  Kevin G. Yager,et al.  Novel photo-switching using azobenzene functional materials , 2006 .

[24]  K. Harris,et al.  Photopatterned liquid crystalline polymers for microactuators , 2006 .

[25]  Yanlei Yu,et al.  How does the initial alignment of mesogens affect the photoinduced bending behavior of liquid-crystalline elastomers? , 2006, Angewandte Chemie.

[26]  G. Fernando,et al.  Investigation of reversible photo-mechanical properties of azobenzene-based polymer films by nanoindentation , 2006 .

[27]  K. Harris,et al.  Large amplitude light-induced motion in high elastic modulus polymer actuators , 2005 .

[28]  T. Endo,et al.  Reversible photo-mechanical switching behavior of azobenzene-containing semi-interpenetrating network under UV and visible light irradiation , 2005 .

[29]  Marina Saphiannikova,et al.  Dielectric and Mechanical Properties of Azobenzene Polymer Layers under Visible and Ultraviolet Irradiation , 2005 .

[30]  M. Shelley,et al.  Fast liquid-crystal elastomer swims into the dark , 2004, Nature materials.

[31]  T. Ikeda,et al.  Effect of Cross-linking Density on Photoinduced Bending Behavior of Oriented Liquid-Crystalline Network Films Containing Azobenzene , 2004 .

[32]  T. Ikeda,et al.  Photomechanics: Directed bending of a polymer film by light , 2003, Nature.

[33]  Bin Li,et al.  Light‐Driven Side‐On Nematic Elastomer Actuators , 2003 .

[34]  Paul Rochon,et al.  Photoinduced motions in azo-containing polymers. , 2002, Chemical reviews.

[35]  E. Terentjev,et al.  UV manipulation of order and macroscopic shape in nematic elastomers. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[36]  Zouheir Sekkat,et al.  Photoreactive organic thin films , 2002 .

[37]  U. Pietsch,et al.  Atomic force microscopy inspection of the early state of formation of polymer surface relief gratings , 2001 .

[38]  B. Gallot,et al.  Synthesis and Structure Characterization of Liquid Crystalline Polyacrylates with Unconventional Fluoroalkylphenyl Mesogens , 2001 .

[39]  H. Finkelmann,et al.  A new opto-mechanical effect in solids. , 2001, Physical review letters.

[40]  H. Finkelmann,et al.  A Simple and Versatile Synthetic Route for the Preparation of Main-Chain, Liquid-Crystalline Elastomers , 2000 .

[41]  Toemsak Srikhirin,et al.  Light-induced softening of azobenzene dye-doped polymer films probed with quartz crystal resonators , 2000 .

[42]  Nirmal K. Viswanathan,et al.  Surface relief structures on azo polymer films , 1999 .

[43]  Paul Rochon,et al.  Model of laser-driven mass transport in thin films of dye-functionalized polymers , 1998 .

[44]  Tomiki Ikeda,et al.  Rapid optical switching by means of photoinduced change in refractive index of azobenzene liquid crystals detected by reflection-mode analysis , 1997 .

[45]  Lian Li,et al.  Polarized Laser Induced Holographic Surface Relief Gratings on Polymer Films. , 1995 .

[46]  E. Fischer.  Calculation of photostationary states in systems A .dblarw. B when only A is known , 1967 .