Actuators based on liquid crystalline elastomer materials.

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCE materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic fields, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the properties of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described.

[1]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[2]  J. R.,et al.  Chemistry , 1929, Nature.

[3]  C. Tanford.  Macromolecules , 1994, Nature.

[4]  A. Mandel.  II In France , 1967 .

[5]  Miss A.O. Penney.  (b) , 1974, The New Yale Book of Quotations.

[6]  H. Finkelmann,et al.  Investigations on liquid crystalline polysiloxanes, 1. Synthesis and characterization of linear polymers , 1980 .

[7]  C. Greenwood,et al.  Polymers in nature , 1980 .

[8]  R. Zentel,et al.  Stress‐induced orientation in lightly crosslinked liquid‐crystalline side‐group polymers , 1987 .

[9]  Johannes J. Meyer,et al.  X-ray investigations of linear and cross-linked liquid-crystalline main chain and combined polymers , 1987 .

[10]  M. Warner,et al.  Theory of nematic networks , 1988 .

[11]  G. Kumar,et al.  Photochemistry of azobenzene-containing polymers , 1989 .

[12]  S. Iijima.  Helical microtubules of graphitic carbon , 1991, Nature.

[13]  G. Mitchell,et al.  Memory effects in liquid crystal elastomers , 1991 .

[14]  H. Finkelmann,et al.  Nematic liquid single crystal elastomers , 1991 .

[15]  Ferroelectric liquid‐crystalline elastomers , 1994 .

[16]  Heino Finkelmann,et al.  Liquid crystal elastomers: Influence of the orientational distribution of the crosslinks on the phase behaviour and reorientation processes , 1994 .

[17]  M. Schadt,et al.  Photo-Generation of Linearly Polymerized Liquid Crystal Aligning Layers Comprising Novel, Integrated Optically Patterned Retarders and Color Filters , 1995 .

[18]  R. Zentel,et al.  Photo-crosslinking in freely-suspended films of ferroelectric lc-polymers* , 1995 .

[19]  Stephen M. Kelly,et al.  Photo-Induced Alignment and Patterning of Hybrid Liquid Crystalline Polymer Films on Single Substrates , 1995 .

[20]  E. Terentjev,et al.  Nematic elastomersA new state of matter , 1996 .

[21]  P. Gennes,et al.  Artificial muscles based on nematic gels , 1997 .

[22]  P. G. de Gennes,et al.  Dynamics and Thermodynamics of Artificial Muscles Based on Nematic Gels , 1997 .

[23]  T. Kinoshita.  Photoresponsive membrane systems , 1998 .

[24]  Freestanding ferroelectric elastomer films , 1998 .

[25]  H. Finkelmann,et al.  Director reorientation via stripe‐domains in nematic elastomers: influence of cross‐link density, anisotropy of the network and smectic clusters , 1998 .

[26]  Eugene M. Terentjev,et al.  Liquid-crystalline elastomers , 1999 .

[27]  F. Kremer,et al.  Mechanical Deformation Behavior in Highly Anisotropic Elastomers Made from Ferroelectric Liquid Crystalline Polymers , 1999 .

[28]  Oswald Prucker,et al.  Photochemical Attachment of Polymer Films to Solid Surfaces via Monolayers of Benzophenone Derivatives , 1999 .

[29]  R. Zentel,et al.  Ferroelectric liquid crystalline elastomers, 1. Variation of network topology and orientation , 2000 .

[30]  R. Zentel,et al.  Ferroelectric liquid crystalline elastomers, 2. Variation of mesogens and network density , 2000 .

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

[32]  M. Itkis,et al.  Effect of rehybridization on the electronic structure of single-walled carbon nanotubes. , 2001, Journal of the American Chemical Society.

[33]  R. Zentel,et al.  Elastic Properties of Liquid Crystal Elastomer Balloons , 2001 .

[34]  Banahalli R. Ratna,et al.  Liquid Crystal Elastomers with Mechanical Properties of a Muscle , 2001 .

[35]  R. Zentel,et al.  Liquid Crystal Elastomer Balloons , 2001 .

[36]  Peter Palffy-Muhoray,et al.  Tunable Mirrorless Lasing in Cholesteric Liquid Crystalline Elastomers , 2001 .

[37]  Spontaneous thermal expansion of nematic elastomers , 2001, cond-mat/0106138.

[38]  Andrew G. Glen,et al.  APPL , 2001 .

[39]  Y. Mao,et al.  Cholesteric elastomers: deformable photonic solids. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[40]  S. Clarke,et al.  Effect of crosslinker geometry on equilibrium thermal and mechanical properties of nematic elastomers. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[41]  M. Lösche,et al.  Structure and elastic properties of smectic liquid crystalline elastomer films. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[42]  Liquid crystal H-bonded polymer networks under mechanical stress , 2003 .

[43]  P. Keller,et al.  Nematic Elastomer Fiber Actuator , 2003 .

[44]  Tomiki Ikeda,et al.  Anisotropic Bending and Unbending Behavior of Azobenzene Liquid‐Crystalline Gels by Light Exposure , 2003 .

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

[46]  P. Keller,et al.  An Artificial Muscle with Lamellar Structure Based on a Nematic Triblock Copolymer , 2004 .

[47]  Yue Zhao,et al.  Azopyridine Side Chain Polymers: An Efficient Way To Prepare Photoactive Liquid Crystalline Materials through Self-Assembly , 2004 .

[48]  R. Zentel,et al.  Study of smectic elastomer films under uniaxial stress , 2004 .

[49]  Guojun Liu,et al.  Photoactive thermoplastic elastomers of azobenzene-containing triblock copolymers prepared through atom transfer radical polymerization , 2004 .

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

[51]  K. Urayama,et al.  Anisotropic mechanical properties of thermoplastic elastomers in situ reinforced with thermotropic liquid‐crystalline polymer fibers revealed by biaxial deformations , 2005 .

[52]  Ping Xie,et al.  Liquid crystal elastomers, networks and gels: advanced smart materials , 2005 .

[53]  Phase transitions and soft elasticity of smectic elastomers. , 2004, Physical review letters.

[54]  T. Ikeda,et al.  Photodeformable Polymers: A New Kind of Promising Smart Material for Micro- and Nano-Applications , 2005 .

[55]  K. Harris,et al.  Thermo‐Mechanical Responses of Liquid‐Crystal Networks with a Splayed Molecular Organization , 2005 .

[56]  A Versatile Preparation Route for Thin Free-Standing Liquid Single Crystal Elastomers , 2005 .

[57]  Benoit Ladoux,et al.  Micro-actuators: when artificial muscles made of nematic liquid crystal elastomers meet soft lithography. , 2006, Journal of the American Chemical Society.

[58]  Patrick Keller,et al.  Artificial muscles based on liquid crystal elastomers , 2006, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[59]  Yanlei Yu,et al.  Soft actuators based on liquid-crystalline elastomers. , 2006, Angewandte Chemie.

[60]  Eugene M. Terentjev,et al.  Self‐Assembled Shape‐Memory Fibers of Triblock Liquid‐Crystal Polymers , 2006 .

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

[62]  Heino Finkelmann,et al.  Photocrosslinkable Liquid Crystal Main‐Chain Polymers: Thin Films and Electrospinning , 2007 .

[63]  James F. Rusling,et al.  Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules , 2007, Advanced materials.

[64]  R. Zentel,et al.  (Photo)crosslinkable Smectic LC Main‐Chain Polymers , 2007 .

[65]  Shaoqin Gong,et al.  Reversible Infrared Actuation of Carbon Nanotube–Liquid Crystalline Elastomer Nanocomposites , 2008 .

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

[67]  R. Grubbs,et al.  Well-defined liquid crystal gels from telechelic polymers. , 2008, Journal of the American Chemical Society.

[68]  P. Keller,et al.  Micron-sized main-chain liquid crystalline elastomer actuators with ultralarge amplitude contractions. , 2009, Journal of the American Chemical Society.

[69]  S. Serak,et al.  Azobenzene liquid crystal polymer-based membrane and cantilever optical systems. , 2009, Optics express.

[70]  Hongrui Jiang,et al.  Synthesis of a photoresponsive liquid-crystalline polymer containing azobenzene. , 2009, Macromolecular rapid communications.

[71]  Ying Zhang,et al.  Photoresponsive side-chain liquid crystalline polymers with an easily cross-linkable azobenzene mesogen , 2009 .

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

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

[74]  Shin‐Tson Wu,et al.  Adaptive liquid lens actuated by photo-polymer. , 2009, Optics express.

[75]  T. Ikeda,et al.  Can sunlight drive the photoinduced bending of polymer films , 2009 .

[76]  M. Hoffmann,et al.  Photo-Crosslinked Side-Chain Liquid-Crystalline Elastomers for Microsystems , 2009 .

[77]  R. Rosenfeld.  Nature , 2009, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[78]  Synthesis, Structure, and Properties of Single‐Walled Carbon Nanotubes , 2009 .

[79]  C. Ohm,et al.  A Continuous Flow Synthesis of Micrometer‐Sized Actuators from Liquid Crystalline Elastomers , 2009, Advanced materials.

[80]  Richard A. Evans,et al.  Photo-responsive systems and biomaterials: photochromic polymers, light-triggered self-assembly, surface modification, fluorescence modulation and beyond , 2010 .

[81]  E. Terentjev,et al.  Dispersion and Alignment of Carbon Nanotubes in Liquid Crystalline Polymers and Elastomers , 2010, Advanced materials.

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

[83]  Andreas Lendlein,et al.  Progress in actively moving polymers , 2010 .

[84]  L. Ionov.  Actively-moving materials based on stimuli-responsive polymers , 2010 .

[85]  Yanlei Yu,et al.  Visible light induced bending and unbending behavior of crosslinked liquid-crystalline polymer films containing azotolane moieties , 2010 .

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

[87]  Yanlei Yu,et al.  Photodeformable polymer material: towards light-driven micropump applications , 2010 .

[88]  C. Ohm,et al.  Liquid Crystalline Elastomers as Actuators and Sensors , 2010, Advanced materials.

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

[90]  C. Ohm,et al.  Preparation of actuating fibres of oriented main-chain liquid crystalline elastomers by a wetspinning process , 2011 .

[91]  Humberto Campanella,et al.  Localised actuation in composites containing carbon nanotubes and liquid crystalline elastomers. , 2011, Macromolecular rapid communications.

[92]  P. Keller,et al.  Micron-sized liquid crystalline elastomer actuators , 2011 .

[93]  J. E. Marshall,et al.  Bending kinetics of a photo-actuating nematic elastomer cantilever , 2011 .

[94]  Haifeng Yu,et al.  Photocontrollable Liquid‐Crystalline Actuators , 2011, Advanced materials.

[95]  M. Hoffmann,et al.  Liquid‐Crystalline Elastomer Microvalve for Microfluidics , 2011, Advanced materials.

[96]  C. Ohm,et al.  Microfluidic synthesis of highly shape-anisotropic particles from liquid crystalline elastomers with defined director field configurations. , 2011, Journal of the American Chemical Society.

[97]  Hongrui Jiang,et al.  Reversible white-light actuation of carbon nanotube incorporated liquid crystalline elastomer nanocomposites , 2011 .

[98]  J. E. Marshall,et al.  Nanoparticle-Liquid Crystalline Elastomer Composites , 2012 .

[99]  Huisheng Peng,et al.  Unusual reversible photomechanical actuation in polymer/nanotube composites. , 2012, Angewandte Chemie.

[100]  J. E. Marshall,et al.  Carbon-nanotube sensitized nematic elastomer composites for IR-visible photo-actuation , 2012 .

[101]  Hongrui Jiang,et al.  Direct Sun‐Driven Artificial Heliotropism for Solar Energy Harvesting Based on a Photo‐Thermomechanical Liquid‐Crystal Elastomer Nanocomposite , 2012 .