Effect of BaTiO3 nanoparticle on Electro Optical Properties of Polysiloxane Liquid Crystal Polymer

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1 Journal Of Industrial Engineering Research ISSN Journal home page: (1): RSEARCH ARTICLE Effect of BaTiO3 nanoparticle on Electro Optical Properties of Polysiloxane Liquid Crystal Polymer Khalid Al.Ammar and Zahraa kazem Physics Department college of Education for pure science Babylon University Address For Correspondence: Khalid Al.Ammar and Zahraa kazem, Physics Department college of Education for pure science Babylon University Received 3 January 2016; accepted 26 March 2016; published 31 March 2016 A B S T R A C T In this paper the nonlinearity of liquid crystal cell doped with Barium Titanate nanoparticales by considering their selective absorption. Such nonlinearities are promising for optical processing applications and optical limiters. Systems displaying thermal nonlinearities are particularly attractive as the maximum nonlinearity may occur in the absence of an applied field and additionally this nonlinearity can be controlled by the reorientation of the liquid crystal. This study focuses on the electro optic properties of polymers with a dfferent molecular weights based on the polysiloxane backbone, It is found that there is a strong coupling between the mesogenic side chain groups snd the polymer chain that the elasticity of the polymer chain plays a strong role even in the static electro optic properties. The switching times (on) and (off) have been measured through the period between planer and homotropic alignment which happens under the electrical field effect. Additionally, it is found that adding barium titanate nanoparticles moieties will decrease the phase transition temperatures and thus decreasing of switching times. The variation of the threshold voltage is measured at constant steps below nematic isotropic transition temperature ( ) for series of polymers. It is found that the high molecular weights of polymers have great threshold voltage of the electro optic response and this is related to the intrinsic elastic constant of the liquid crystal polymers. The performance of the electro optical cells has improved after add the barium titanate would reduce the contribution of the dibole moment of the cyano groub baralle to the molecular long axis of the mesogenic unit and thus reduce density of the mesognic unit attached to polymer chaine and lead to a Increases of dielectric anisotropic ( ) and thus enhanced backbone mobility for the system. Key words: Barium Titanate nanoparticales, Polysiloxane, electro optic properties INTRODUCTION Many of modern technologies require materials with unusual combinations of properties that cannot be met by the conventional metal, alloys, ceramics, and polymeric materials. This is especially true for materials that are needed for aerospace, underwater, and transportation applications [1]. A composite material is basically a combination of two or more materials, each of which retains its own distinctive properties. Generally the term composite is applied to materials that are created by mechanical bonding two or more different materials together. The resulting materials have characteristics that are not characteristics of the component in isolation [2]. Polymers consist of large organic molecules (macromolecules) of repeating small structural units (monomers) connected together in a process called polymerization [3]. Each molecule is composed of thousands of atoms connected by covalent chemical bonds, molecules in polymer attract each other by forces that depend Open Access Journal Published BY IWNEST Publication 2016 IWNEST Publisher All rights reserved This work is licensed under the Creative Commons Attribution International License (CC BY). To Cite This Article: Khalid Al.Ammar and Zahraa kazem., Effect of BaTiO3 nanoparticle on Electro Optical Properties of Polysiloxane Liquid Crystal Polymer. Journal of Industrial Engineering Research,, 2(1): 23-30, 2016

2 24 Khalid Al.Ammar and Zahraa kazem,2016 on the type of the polymer. As polymers consist of huge, combined molecules which are hard to polymer[4].control, limited crystal connections can be seen in polymers associated with its low temperature[5]. It is only in limited regions that a linear chain of molecules can arrange themselves in an organized form. In the solid state, polymers are comprised of crystalline and non-crystalline regions [6]. Although the terms nanomaterial and nanocomposite represent new and exciting fields in materials science, such materials have actually been used for centuries and have always existed in nature [7]. However, it is only recently that the means to characterise and control structure at the nanoscale have stimulated rational investigation and exploitation. A nanocomposite is defined as a composite material where at least one of the dimensions of one of its constituents is on the nanometre size scale [8]. Material that exhibit liquid crystalline phases have been recognized for almost a century [9,10] yet it is only over the last two decades that such materials have evolved from the laboratory curiosity stage to become the basis of a new science. Liquid crystalline phases have recently been called the fourth state of matter [11]. However, such a definition belies the richness of structural properties that characterizes the many different liquid crystalline phases and leads to the immense interest in their behavior. Although the case of liquid crystals is an intermediate state between solid and liquid cases, but this does not mean that the liquid crystals to possess properties that distinguish them from cases which owns independent dioxin her, just do not get in the solid state and the status of liquid [12, 13], and an example to the liquid state is characterized by molecules that have the same properties in the directions are all but in the liquid crystal molecules depends on the direction in determining the properties (ie it does not hold the same properties in all directions). Although the liquid crystals possess _khasaisa back to both solid and liquid cases, they have their own advantages not found in both accompanied by an increase in entropy [14]. Experimental: The procedures followed for the construction of electro optic cells with predefind director orientation in these investigations were similar to those developed for low molecular weight liquid crystal.blazers Z20 tin oxide coated glass slides were used for all electro optic cells constructed in this work. This was easily cut and was sufficiently flat to allow the fabrication of cells with parallel plate separation to within a few seconds of arc. The glass was cut into plate of approximately 6cm 2 area, and etched using HCL acid with zinc metal powder as a catalyst to give a 2cm 2 electrode surface. Each glass plate was then washed hand- by hand in soup and water and cleand in an ultrasonic bath for 30 minutes at 65C º. The plates were then rinsed in distilled water and dried in an oven for 20 minutes at 60 C º. This treatment produced plates sufficiently clean for the surface treatment procedure, which is the subject of the next section. In this work One technique was used to achieve uniform planer alignment of the liquid crystal director. The cell electrodes were coated with a thin layer of polyimide precursor [consisting of a 5% solution of Rodehftal 322 (Rh one Poulenc chemical Ltd.) in dimethyl formaimed ], using a spin coater running at 4,500 r.p.m these coated slides were heated in an oven for 30 minutes at 80C º they were then rubbed at room temperature in a single direction with a cloth using controlled repeatable procedure, heated again for 30 minutes at 130C º, finally it will be putted for one hour at 200C º in the oven. Experimental Set up: The most important three devices were used in this work for electro optic measurement are: 1.MK HCS402 3.ALCT The MK 1000 series temperature controller offers precision, accuracy, and stability for temperature measurement and control. It provides temperature resolution and precision to 0.001C º, accommodates both Pltatinum RTD and individually calibrated thermistors as temperature sen, and can optionally control up to four (4) instec hot and cold stages, plates, or chucks. Two operation modes, keypad operation using the front panal of the controller, or software control though pc as well as. Adjustable ramp ( rate of heating / cooling) to user set temperature point. Programmable operation command set. Precisely controls temperature to 0.001C º option save temperature data to the computer. RTD thermositor or thermocouple, LC cell holders for many types of LC cells. Features: 1.Two operation modes,keybad operation using the front panal of the controller, or software control through PC. 2.User adjustable ramp (rate of heating / cooling ) to user set temperature point. 3.Fully programmable without host computer. 4.Wide temperature range.

3 25 Khalid Al.Ammar and Zahraa kazem, Accurate to(0.001c º ) temperature resolution and precision.precisely controls temperature to 0.001C º option savetemperature data to the computer. RTD thermistor or thermocouple, LC cell holders for many types of LC cells. Temperature control system, which includes MK 1000 controller, nitrogen container nitrogen pump (LN2- P), and hot cooling stage. It features, Large viewing Aperture. Dual pane window for better thermal chaber. Inner lid for improved sample temperature uniformity. Vertical and horizontal mounting. Optional precision X- Y micropositionar for sample positioning. Application software, wintemp, allows remote control from host computer. This includes light source, polarizer, rotatble hot cooling stage holder analyzer, and photo detector holder. This test bench allows user to: -Test cell in side of the hot cooling stage can be rotated in full 360 º range. -Arrange polarizer and analyzer perpendicular and parallel to each other. -Light sealable working chamber shields a way the room lighting. -Light source, polarizer and analiyzer are installed in sealed dark sections to prevent the contamination of optical components. -Light sealable working chamber shields a way the lighting. Fig. 1: Electro optic cell Fig. 1: a photograph of the work system

4 26 Khalid Al.Ammar and Zahraa kazem,2016 Fig. 3: materials chemical structures Table 1: Molecular weight and phase transition data polysiloxane TNI 130 T g D P M w Polymer Results: For getting on the switching voltage must be the transmitted light intensity decrement with increasing of the required voltage, so it can be determind to complete switching. The required voltage is increased with increasing of molecular weight M W this is due to viscosity η and the degree of entanglement between the molecules are high. The same behavior was observed for the poly siloxane liquid crystal, although there are some differences in the required voltage. The voltage for the complete orientation are identified, applied to the cell, and calculates the required time to the occurrence of complete orientation. Where Fig (4-8) show switch on time on as function of the time for which the field is switched off before the measurement. Using the system and the method described in work, we have implemented a cyclic experiment in which we use the values of to determine when a steady state is reach. As mentioned in work the approach allows both and to be evaluated. in order to achieve complete switching we typically applied ( ) volt (peak to peak) at a frequency of 500 Hz. The variation of the transmitted light intensity as a function of the applied voltage and the required voltage for each material in this work for complete switching. By reducing the temperature T NI the saturation states showed in these figures shifted, the required voltage for complete switching was increased in this case. the same behavior was observed for the materials in work although the materials in this work show lrger differences between the required voltages for each material compared with the materials in work. Reproducible switching effect were Observed at temperatures close to the nematic isotropic transition temperature where the viscosity of the polymer is relatively low and measurement were made in the range of T NI to T NI -4 for matrials no.1 and 2 and no response to the applied field had been observed for these materials in the smectic phase but measurements were made for the materials no.3.4 and 5 in the range of T NI to T NI 5 at the same time reproducible swiching effects were observed in the smectic phase no.3 show as a function of the time for respectively, each set of experiment were made at constant temperature. The experimental arrangement used for the static electro properties is similarly used for the dynamic electro-optic effects. Fields with a frequency of 500Hz were employed for measurements. The static electro optic properties are important

5 27 Khalid Al.Ammar and Zahraa kazem,2016 because they contain important experiments between the threshold voltage U c and curvature elastic constants K ii and their relationship to composition and temperature for the liquid crystal copolymers. The results obtained for the material in this study are presented in Fig (9). There is a marked reduction in the threshold voltage for both increasing temperature and reducing the molecular weight. In this series of polymers, Fig (10) makes a direct comparison of the threshold voltage obtained in the nematic phase at a constant step below T NI for the series of polymers prepared. It is clear that there is an increase in the threshold voltage with increasing molecular weight. Indeed if the effect of the end groups of the polymer chains are taken into account then the trend will be even more marked. It is emphasized that any dynamic effects arising from changing viscosity have been eliminated in the procedures outlined above. A few contributions, have dealt with measuring the threshold voltage for polysiloxane polymers. Unfortunately, molecular weight data were not given, however the threshold voltages reported are broadly similar to those found here. The marked increase of the threshold voltage with temperature follows similar dependence observed of the materials, in which the mesogenic density along the polymer backbone is changed. It is noticeable that there is no sudden step in the threshold voltage at the transition from nematic to smectic phases for polymers 3. From a smectic phases the value of K 11 is usually similar to that observed for the nematic phase, since layer deformation is a relatively facile process. In the present study, using infrared dichroism to analyze the orientational ordering of the liquid crystalline side-chain polymers on prealigned cells, Also using the different molecular weights to obtain information about the orientational order of the head part, by observing the bands corresponding to the vibrations of the relevant functional groups, where the major vibration absorption band C N occur in the 2235 cm -1 region. The dependence of temperature with different molecular weight M w is shown in Fig. (11). Where crystals. It is evident that the polymers with the highest M w exhibit the lowest of these liquid reflect an incomplete monodomain formation due high viscosity, there was no experimental evidence to suggest that the measurements were anything other than true steady state values. 25 t on(sec) Time left off (sec) Fig. 4: the relation between and time left off for polymer 1 Fig. 5: the relation between and time left off for polymer 2

6 28 Khalid Al.Ammar and Zahraa kazem,2016 Fig. 6: the relation between and time left off for polymer 3 Fig. 7: the relation between and time left off for polymer 4 Fig. 8: the relation between and time left off for polymer 5

7 29 Khalid Al.Ammar and Zahraa kazem,2016 Fig. 9: plots of the measured threshold voltages a function of temperature Vth(volt) Molecular Weight g/mole Fig. 10: aplots of the measured threshold voltages as a function of the molecular at (1and 3) below TNI Fig. 11: Order parameter S as a function of temperature obtained through measurement of the infrared dichroism

8 30 Khalid Al.Ammar and Zahraa kazem,2016 Discussion: In this study, research on the impact of the BaTiO3 nanoparticles on electro-optical properties of liquid crystals polymer polysiloxan with side chian.used different molecular weight, and when adding BaTiO3 nanoparticles which is equal (0.07) to the polymer polysiloxane with side chain will work to increase the viscosity of the polymer, as well as the works of these nanoparticles added to increase connectivity polymer shed when an electric field, and working to reduce the degree phase transition of polymer, this leads to reduce the switching times ( ). Finally redeeming range Syano was chosen because of the interest in electrical characteristics of the polymer could make it particularly suitable for applications, and in any case add BaTiO 3 possible particles increase the density mesogen units which are connected with a series polymer to increase the contribution of dual-electrode parallel group Syano molecules torque along the axis mesogen Group this in turn increases the dielectric anisotropy Δε. It is found that decreasing the molecular weight lower, the phase transition temperature for high molecular weight polymers (materials no.1,2 and 3) a smectic phase is observed with very narrow nematic range however at low molecular weight (material no.4and 5) only the nematic phase is observed. complementary to the reduction of the phase transition temperature with decreasing the molecular weight of the polymers there is a market lowering of the glass transition temperature of value of the glass transition is found to increase as the molecular weight of the polymer is increased. REFERENCES [1] Callister, D.W., "Material Science and Engineering, An Introduction", Sixth Edition, Department of Metallurgical Eng., The University of Utah, John Wiley and Sons, Inc., USA. [2] Arifitekhar, M., "Introduction to Composite Materials", BMEn York,Anchor Press, Doubleday ( 1986). [3] Drexler, K.E., "Engines of Creation,The Coming Era of nanotechnology", New York,Anchor Press, Doubleday. [4] Robertson, J., "Realistic applications of CNTs",Materials Today, 7(5): [5] Aharoni, S.M., "Metal- Filled Plastics", J. Appl. Phys, 43(1). [6] Rahe, S., "Study of Effect X-ray on the physical properties of a polyvinyl pyrrolidon (PVPD)", M.Sc. Thesis, University of Mustansiriah, collage of science. [7] Taniguchi, N., " Proc.of International Conference on Precision Engineering", Tokyo, Part II, Japan Society of Precision Engineering, pp: [8] Mohammed Akram, A., "plastics Chemistry", University of Mosul. [9] Reintzer, F.Monatsh, chem, 9: 421. [10] Shibaev, P. and N.A. Plate, Adv.polym. Sci., 60161,173. [11] Al-Ammar, K. and Z. AL-Maamori, "Effect of Molecular Weight on the Static Electro Optic Properties of Polysiloxane Liquid Crystal Polymers, "Journal of Babylon University/ Pure and Applied Sciences, (6): 22. [12] Brown, G.H. and J.J. wolken, "liquid crystals and biological structures". ISBN: , 3 rd Edition, Academic press, London. [13] C.S., "Liquid Crystals". Cambridge University Press, UK. [14] Kizwini, S.F. Thesis, " Effect of Gold Nanopartcle on Electro Optical Prpperties of Polysiloxane Liquid Crystal Polymer ". Dept. Phys, college of Science, of Babylon University.