Evaluation of the Important Properties of Liquid Crystal Elastomers (LCEs)

Dlzar M. Majeed

College of Engineering, University of Sulaimani

Liquid Crystal Elastomers (LCEs) have been the object of growing interest in recent years due to the combination of mesogenic ordering and rubber elasticity which allows them to respond to thermal stimuli by changing their shape, size and optical properties. The use of LCEs thus makes it possible to convert small quantities of external energy to mechanical energy which makes it easy to be used as energy harvesting. This paper will firstly focus on thermal and mechanical properties of LCEs it will be seen that they will be affected by elasticity of the polymer backbone and the nature of mesogenic monomer. Following this, the focus will turn to the electric field, light, and thermal energy that can be converted into mechanical energy induces thermomechanical, electromechanical and electrooptical effects by such materials. It will be observed that the shape of LCE materials can be changed through changing orientation of LC. Additionally, swollen samples can minimize threshold field by a factor of 200 compared with unswollen samples. Then, the emphasis will go to the impact of mixing nanoparticles with the LCE samples on its behaviour. This is done by increasing crosslinking agent content of the sample and then its impact is shown by the strain-stress curve which leads to reduction in the degree of nematic phase and increase in Young’s modules. The paper then gives a future direction to expand the work for instance its application in photovoltaic systems to convert solar energy into electricity.

Key Words:  liquid crystal elastomers rubber elasticity photovoltaic solar energy crosslinking 


[1]      Helmut R. Brand, Harald Pleiner, and Philippe Martinoty. “Selected Macroscopic Properties of Liquid Crystalline Elastomers”, Soft Matter, 182; DOI:10.1039/b512693m, (2006).

[2]      Ohm C, Brehmer M., and Zentel R. “Liquid Crystalline Elastomers as Actuators and Sensors, Advance Materials, Materials views, DOI: 10.1002/adma.200904059, (2010).

[3]      Nathan, J.D. “Photo-induced deformations of nematic liquid crystal elastomers. Unpub”. PhD thesis, Dept. of Physics and Astronomy, University of Washington State, Pullman, United State, (2010). 

[4]      Wanting R. “Structure-property relations in siloxane-based main chain liquid crystal elastomers and related linear polymers”. Unpub. PhD thesis, Dept. of Polymer Texile & Fiber Engineering, Georgia Institute of Technology, Atlanta, United State, (2007). 

[5]      Warner, M. and Terentjev, E.M. “Liquid Crystal Elastomers”. Oxford; Oxford University Press, (2003). 

[6]      Philippe, M.“Mechanical properties of monodomain side chain nematic elastomers. Proceeding of The

First World Congress on Biomimetics and Artificial Muscle”, Albuquerque, 9-11 Dec., 14, 1-21, (2002).

[7]      Yusril, Y., Yukitada, O. Yusuke, S. and Shoichi, K. “Swelling behavior of liquid crystal elastomers in low molecular weight liquid crystals”. Mathematical Aspect of Complex Fluid III Proceeding, RIMS Symposium, Kyoto, Japan 139-148, (2003). 

[8]      Kempe, Scruggs, Verduzco, Lal, and Fornfield. “Liquid Crystal Elastomers Mechanical Properties”. Nature Materials, vol. 2, pp. 422–431, (2004).

[9]      Donald L., Thomsen III, Keller P., Naciri J., Pink R., Jeon H., Shenoy D, and  Ratna R. B. “Liquid

Crystal Elastomers with Mechanical Properties of a Muscle”, Macromolecules 200, 34, 5868 – 5878, (2001).

[10]   Cladis, P.E. “Liquid crystal elastomers as artificial muscles”. Dynamic Control Systems Proceedings, Summit, USA, 69, pp. 1-8, (2000).

[11]   Madden, J.D.W. “Artificial muscle technology: physical principles and naval prospects”. Oceanic Engineering, IEEE Journal of 29, pp.706-728, (2004).

[12]   Ohm, C., Brehmer, M. and Zentel, R. “Applications of liquid crystalline elastomers”, in R. Jayakumar and S. Nair, eds., Biomedical Applications of Polymeric Nanofibers, pp.10-12, (2012).

[13]   Min-Hui, L. and Patrick, K. “Artificial muscles based on liquid crystal elastomers”. Philosophical Transactions of The Royal Society 364, pp.2763-2777, (2006).

[14]   Shigehiro, H. “Multifunctional liquid crystal elastomers: large electromechanical and electro-optical effects”. The American Institute of Physics 92, pp.1-3, (2008).

[15]   Tomiki, I., Jun-ichi M. and Yanlei, Y. “Photomechanical of liquid-crystalline elastomers and other polymers”. The 21st International Liquid Crystals Conference, Keystone, vol. 46, 506-528, (2006).

[16]   Christian, O., Martin, B. and Rudolf, Z. “Liquid crystalline elastomers as actuators and sensors”. Advanced Materials 22, pp.3366-3387, (2010). 

[17]   Yanlei, Y. and Tomiki, I. “Photodeformable polymers: a new kind of promising smart material for micro-and nano-applications”. Macromolecular Chemistry and Physics 206, pp.1705-1708, (2005).

[18]   Yanlei, Y., Taketo, M., Jun-ichi, M. and Tomiki, I. “Photomechanical effects of ferroelectic liquidcrystalline elastomers containing azobenzene chromophores”. Angewandte Chemie 119, pp.899-901, (2007).

[19]   Miguel, C.L., Heino, F., Peter, P.M. and Michael, S. “Fast liquid-crystal elastomer swims into the dark”. Nature materials 3, pp.307-310, (2004). 

[20]   Yanlei, Y. and Tomiki, I. “Soft actuators based on liquid-crystalline elastomers”. Angewandte Chemie 45, pp.5416-5418, (2006). 

[21]   Tomiki, I. “Photomodulation of liquid crystal orientations for photonic applications”. Journal of Materials Feature Article 13, pp.2037-2057, (2003).

[22]   Yang, H.N., Yuki, A., Kazuyuki, H., and Hiroshi, O. “Measurement of Electrical Induced Shear Strain in Chiral Smectic Liquid Crystal Elestomer”. The 2011 International workshop on Physics of PolyDomain Liquid Crystalline Elastomers. Institute of Natural Sciences, China. Last mod. 9 Jun  2011. Viewed on 3 May 2012 at http:// ins.sjtu.edu.cn/ programs/2011/ ws_ppdlce/list.html .

[23]   Kenji, U., Seiji, H. and Toshikazu, T. “Deformation coupled to director rotation in swollen nematic elastomers under electric fields”. American Chemical Society 39, pp.1943-1949, (2006).

[24]   Yusril, Y. “Low-voltage-driven electromechanical effects of swollen liquid-crystal elestomers”. The American Physical Society 71, pp.1-8, (2005).  

[25]   Dong-Uk, C. “Electrical effects of swollen polydomain liquid crystal elastomers”. Journal of the Physical Society of Japan 75, 1-4, (2006). 

[26]   Reza, M., Christopher, M.S., Jawad, N. and Banahalli, R.R. “Enhanced thermomechanical properties of a nematic liquid crystal elastomer doped with gold nanoparticles”. Sensors and Actuators A: Physical 178, pp.175-178, (2012).

[27]   Vivi, H., Ahmad, K. and Yusril, Y. “Study of thermo-mechanical effects of dry main-chain liquid crystal elastomers (MCLCEs)”. Proceedings of the 3rd Asian Physics Symposium, 22-23 Jul., 97-101, (2009).

[28]   Courty S., Mine J., Tajbakhsh A. R., and Terenthev E. M. “Nematic elastomers with aligned carbon nanotubes: New electromechanical actuators”,  Europhysics letters, Europhys. Lett., 64 (5), pp. 654– 660, (2003). 

[29]   Hiscock, T., Warner, M. and Palffy-Muhoray, P. “Solar to electrical conversion via liquid crystal elastomers”. Journal of Applied Physics 109, pp.1-9, (2011).