The international 3 rd. Scientific Conference of the College of Science 2015 1 Journal of University of Kerbala Effect of MWCNT on Electro-Optical Properties of Liquid Crystal Sudad S. Ahmed 1 ,Rawa K. Ibrahim 2 , Asama N.Naje 1 , Kais Al-Naimee 1 University of Baghdad, Collage of Science, department of physics 1 , Ministry of Science and Technology 2 soudadbassam@gmail.com,Rawak2070@gmail.com , naje.as75@gmail.com, Kais.al-naimee@ino.it. Abstract Dispersions of multi wall carbon nanotubes (MWCNTs) in liquid crystals (LCs)type 5CB have attracted attention due to their unique properties and possible applications in photonics and electronics. The results of the investigations of improved the electro-optical properties of liquid crystal optical switch are being presented here. The addition of MWCNT showed fast response time ,fast rise time,and lower threshold voltage. Key words: Liquid crystal, MWCNT, electro-optical properties, optical switch. Introduction Liquid crystals (LCs) turn out to be excellent hosts for multi walled carbon nanotubes (MWCNTs). Having molecular structure similar to MWCNTs, LCs perfectly incorporate MWCNTs into own structure. Particularly, the liquid crystalline orientational order can be imposed on MWCNTs so that aligned ensembles of these particles can be attained [1] . This alignment can be patterned by pattering alignment of LC host. Furthermore, the alignment axis of MWCNTs can be easily driven by the LC reorientation in the external field [2] ; MWCNTs follow reorientation of LC director demonstrating guest-host effect known for molecular solutions and dispersions of anisotropic nanoparticles in LC hosts [3] . Finally, LC can be removed and thus pure aligned MWCNTs can be obtained [4] . This altogether means that LC gives unique opportunity for controllable alignment of MWCNTs. The LC-MWCNTs systems are not limited to nematic matrices. A series of unique LC-MWCNTs composites based on thermotropic and lyotropic materials with different LC mesophases is developed and characterized [5 ][6][7][8][9] A present work is focused on remarkable dielectric, electro-optical and micro- structural peculiarities of LC-MWCNTs dispersions, their correlation and mutual influence.