XRD Pattern of Liquid Crystal Monomer Acrylate that ...

D

J. Chem. Chem. Eng. 6 (2012) 199-208

DAVID

PUBLISHING

XRD Pattern of Liquid Crystal Monomer Acrylate that Conjugated with Cholesterol and p-Hydroxyphenyl2-Methyl Butanoic Afrizal1*, Muhammad Hikam2, Bambang Soegiyono2 and Asep Riswoko3 1. Faculty of Mathemathics and Natural Science, University Of State Jakarta, Jakarta 13220 Indonesia 2. Department of Materials Science, Faculty of Mathemathics and Natural Science, University Of Indonesia, Depok 16424, Indonesia 3. Center for Material Technology, BPPT, Jl. MH.Thamrin 8 Jakarta 10310, Indonesia Received: November 01, 2012 / Accepted: November 30, 2012 / Published: December 25, 2012. Abstract: It was successfully synthesized liquid crystal monomer acrylate that conjugated with two mesogens were cholesterol and p-Hydroxyphenyl-2-Methyl Butanoat which called MA (monomer cholesteryl acrylate) and monomer (S)-(+)-4-(2-Methyl butanoat-1-butyloxy)phenyl 4-[1-(propenoyloxy) butyloxy]benzoate (MB). Two monomers were characterization by Differential Scanning Calorimetry (DSC), Polarization Optical Microscopy (POM), X Ray Diffraction (XRD). Mesophase temperature of MA and MB are 81.28 oC and 54.36 oC. Textures analysis by POM showed MA was oily streak and MB was schlieren. XRD pattern show the strongest 3 peaks of MA at room temperature are (2Theta, deg): 2.7153; 5.2992 and 18.8500. Strongest 3 peaks of MB at room temperature are (2Theta, deg): 9.1726; 9.7707 and 12.5389. XRD pattern MA and MB at mesophase and above mesophase temperature that each peaks disappear. Key words: Liquid crystal, cholesteryl acrylate, p-hydroxyphenyl-2-methylbutanoat.

1. Introduction The liquid crystal had kept itself quiet for a half century until the early 70’s. Since then, it has caught the vast interest of both science and industry. It has been applied especially in the display industry, such as in portable TVs and notebook and desktop computers [1]. One type of liquid crystal that has been widely used type of liquid crystal acrylate group. Several new product have been synthesized by using acrylates as precursors. An advantage of acrylate chemistry is that the starting materials can be highly purified and the free-radical cure chemistry need not involve any ionic compounds (Mucha 2003). The resulting films can have high volume resistivity if used with high

*

Corresponding author: Afrizal, M.Si., research field: liquid crystal. E-mail: [email protected].

resistivity liquid crystal mixtures, a necessary requirement for display applications [2]. It was successfully synthesized Liquid Crystal Monomer Acrylate that conjugated with two mesogens were cholesterol and p-Hydroxyphenyl-2-Methyl Butanoat. Acrylate monomer conjugated with cholesterol mesogen has been synthesized using a novel method of esterification using DCC (1,3-Dicyclohexylcarbodiimide) and DMAP (4-(N,N dimethylamino)pyridine) [2-4]. Figure 1 show structure of MA (monomer cholesteryl acrilat) and (S)-(+)-4-(2-Methyl butanoat-1-butyloxy) phenyl 4-[1-(propenoyloxy) butyloxy]benzoate (MB). Cholestryl acrylate is one of derivatifes of cholesterol that include the type of liquid crystals in 1888 a scientist cholesteric, Reinitzer find one of its kind that is cholesteric benzoate. Liquid crystal mesophase cholesteric nematic known as chiral phase

2

XRD Pattern Of Liquid Crystal Monomer Acrylate That Conjugated With Cholesterol and p-Hydroxyphenyl- 2-Methyl Butanoic

(N*). Attractive properties in this phase is to establish its structure a spiral helix. ChLCs (Cholesteric liquid

Figure. 1 structures of MA and MB.

crystals) continue to attract a great deal of attention because their unique helical structures give rise to selective reflection of incident light [3, 4]. In contract to the liquid crystal monomer MA, MB monomer liquid crystal is one kind of liquid crystal of benzoic acid ester type. Previous research has been made of liquid crystal of this kind of benzoate esters, namely chiral side-chain liquid crystal polyacrylates containing (S)-4’-(-2-methyl-1-butyloxy) phenyl 4-[1-propenoyloxy)alkyloxy] benzoate [5]. These liquid crystal have chiral phase smektic (Smc*). Liquid crystal properties of this type generally have ferroelectric, which this liquid crystal for LCD technology applications and other applications. Therefore, the synthesis of liquid crystal research benzoate esters of this type to be attracted to the more commonly found types of liquid crystal type other benzoate esters. In this study the type of liquid crystal ferroelectric discuss benzoic ester type are p-methyl-2-hydroxylphenylbutanoat. In this paper special report XRD pattern of both Liquid Crystal Monomer Acrylate that conjugated with cholesterol and p-Hydroxylphenyl-2-Methyl Butanoat. The result of XRD analysis on a liquid crystal MA and MB will be discussed with the results of thermal analysis using DSC and liquid crystal texture analysis of MA and MB using POM.

2. Experiments Monomer Cholesteryl Acrylate was synthesized from precursor acryloyloxy buthoxy benzoate with cholesterolusing a novel method of esterification. The chemical structure of monomer cholesteryl acrylate was characterized by Perkin Elmer FT-IR

Spectrometer. In FT-IR spectrum, the absorb bands at 770.58 cm-1 represent aromatics group, 964.42 cm-1 represent cyclohexnane, 1,204.57 cm-1 represent benzene derivate, 1,370 cm-1 represent C=O at acrylate (ester), 1,467.85 cm-1 represent -C-H (alkana), 1,733.7 cm-1 and 1,708.6 cm-1 represent the ester group and carboxyl group, respectively, and 2,936.67-3,522.08 represent -CH2- group in chain alkane [5]. The second monomers were prepared using a novel method of steglich esterification between acrylate precursor acrylate with p-Hydroxylphenyl-2-Methyl Butanoic. Synthesis of chiral compound (S)-(+)-2-HFM derived from acid (S)-(+)-2-methyl butanoic which has a chiral carbon.The chemical structure of monomer (S)-(+)-4-(2-Methyl butanoic-1-butyloxy)phenyl 4-[1-(propenoyloxy) butyloxy]benzoate was characterized by Perkin Elmer FT-IR Spectrometer. Peaks are observed including peak 3,323 cm-1 which shows the phenyl group (aromatic), 2,851 cm-1 peak indicating alkyl [6-10]. XRD pattern of monomer MA and monomer MB were performed using a Shimadzu XRD 7,000, diffractometer equipped with a copper anode producing CuKα radiation (λ = 1.54 Å), diffracted beam flat nickel monochromator, and scintillation detector. The sample was suspended horizontal.

3. Results and Discussion According to Mihara et al. [9] monomer from acrylate exhibited mesophase properties depending upon the helical pitch length, which itself was dependent with temperature. Based on thermal analysis result by DSC, it be obtained information that monomer MA and MB temperature of mesophase are


81.28 oC and 54.36 oC. POM (polarized optical microscopy) observations at mesophase temperature of monomer MA showed gradjean or oily texture visible streak, which seemed like a pipe line which divides the crystal texture. At high temperatures (above mesophase temperature), the state of monomer having a clear point. Monomer state phase transformation from solid is clear isotropic state, where the texture color with the light polarized when the time does not reflect the typical color. Colors on each component clear and transparent, so that when observed using POM, does not look like the typical colors during the previous state. XRD diffraction patterns of MA at each measurement temperature produce a sharp three peaks. At room temperature, show the peak in 2theta 2.7513; 5.2992 and 18.5800. At mesophase temperature there is a peak in 2theta 2.6820; 2.9600 and 5.2488. While at temperatures above mesophase there is a peak in 2theta 17.1060; 23.1000 and 42.6800 (Figure 3). Figure 4 shows the texture of monomer MB at RT (room temperature), and when sample heated until 75 o C, revealing sample schlieren texture of a chiral mesiphase smectic C (SmC*) as shown by Figure 4. Further heating of the sample change phase to isotropic phase is uniform. XRD diffraction pattern of monomer MB at each measurement temperature produces a sharp three peaks at room temperature in 2theta 9.1726; 9.7707 and 12.5389. At mesophase temperature there is a peak in 2theta 18.3000; 7.7561 and 18.6600. While at temperatures above mesophase there is a peak in 2theta 21.3650; 18.7291 and 22.6519 (Figure 5).

3

Figure 2 Analysis texture of Monomer MA by POM (RT: room temperature, MT: Mesophase temperature, AMT: above mesophase temperature). RT

MT

AMT

Figure 3 XRD pattern of Monomer MA (R: room temperature, M: Mesophase temperature, A: above mesophase temperature).

RT

MT

AMT

Figure 4 Analysis texture of Monomer MB by POM (RT: room temperature, MT: Mesophase temperature, AMT: above mesophase temperature).

RT

MT

AMT

RT

MT

AMT

4


Figure 5 XRD pattern of Monomer MB (R: room temperature, M: Mesophase temperature, A: above mesophase temperature). Table 1 FWHM of monomer MA. At room temperature Peak 2θ (deg) d (Å) FWHM (deg) 2.7153 32.51138 0.13970 5.2992 16.66315 0.13400 18.5800 4.77168 0.22080 At mesophase temperature Peak 2θ (deg) d (Å) FWHM (deg) 2.6820 32.91497 0.17140 2.9600 29.82422 0.10900 5.2488 16.82304 0.16090 At above mesophase temperature Peak 2θ (deg) d (Å) FWHM (deg) 17.1060 5.17939 4.10800 23.1000 3.84721 0.00000 42.6800 2.11678 3.44000

Table 1 shown are several values of FWHM (Full Width at Half Maximum) for monomer MA. The values of FWHM monomer MA at room temperature lower than FWHM at mesophase temperature and above mesophase temperature. Therefore the peak at room temperature looks very sharp. While the monomer MA at mesophase temperature and above mesophase temperature the peak looks rather broad peaks. Differences width of the peaks at each temperature will be seen more clearly in Figure 5. XRD pattern of Figure 5 is MB each temperature conditions. Three conditions temperatures are room temperature, mesophase temperature, and above mesophase temperature. The values of FWHM for monomer MB can be seen in Table 2. Analysis of the values of FWHM like for monomer MA. The peaks that appear at room temperature looks sharper than at mesophase temperature and above at mesophase temperature. Differences in peak width at each temperature will be seen more clearly in Figure 5. XRD pattern of Figure 5 is MB each temperature conditions. Three conditions temperatures are room temperature (24 oC),

mesophase temperature, and above mesophase temperature. In general the values of Full Width at Half Maximum for monomer MA and MB at room Table 2 FWHM of monomer MB. at room temperature d (Å) FWHM (deg) 9.63350 0.20930 9.04510 0.22610 7.05375 0.21340 at mesophase temperature Peak 2θ (deg) d (Å) FWHM (deg) 18.3000 4.84405 0.71380 7.7561 11.38940 0.14500 18.6600 4.75140 0.88000 at above mesophase temperature Peak 2θ (deg) d (Å) FWHM (deg) 21.3650 4.15555 0.31000 18.7291 4.73403 0.26540 22.6591 3.92229 0.21040 Peak 2θ (deg) 9.1726 9.7707 12.5389

Figure 6

XRD pattern of MA.

Figure 7

XRD pattern of MB.


temperature about 0.13-0.22 oC, which is lower than the values of FWHM at mesophase temperature and above mesophase temperature. We can conclude that monomer MA and MB are well crystallized material and indicating the layer structure at room temperature. According to previous research, The shift of the maximum of the broad peak towards higher angle values indicates higher packing density in the SmC* phase, than in the isotropic and chiral nematic phases, giving the values decreasing with temperature [11].

4. Conclusions DSC thermal analysis result obtained information that the sample of monomer MA has two melting point at temperatures of 85 oC and 90 oC. Texture observation of monomer MA by POM at room temperature showed textures of crystalline cholesteryl acrylat. Texture of the surface of the monomer molecules appear parallel and arranged with a regular lattice. At a temperature of 85 oC gradjean or oily texture visible streak, which seemed like a pipe line which divides the crystal texture. the texture of monomer MB at 75 oC is schlieren texture of a chiral mesiphase smectic C (SmC*). XRD pattern of MA at room temperature are (2Theta, deg): 2.7153; 5.2992 and 18.8500. At mesophase temperature there is a peak in 2theta 2.6820; 2.9600 and 5.2488. While at temperatures above mesophase there is a peak in 2theta 17.1060; 23.1000 and 42.6800. XRD pattern of MB at room temperature are (2Theta, deg): 9.1726; 9.7707 and 12.5389. At mesophase temperature there is a peak in 2theta 18.3000; 7.7561 and 18.6600. While at temperatures above mesophase there is a peak in 2theta 21.3650; 18.7291 and 22.6519. Temperature is a factor that greatly affects the properties of liquid crystals of a compound mesophase. Analysis of the crystalline monomer can be seen from peak FWHM (full width at half maximum).

Acknowledgments

5

This research supported by some laboratory equipments in STP BPPT laboratory, Department of Material Science UI, Research Laboratory of Department Chemistry in University State of Jakarta, and joint research with grand research from Faculty of Mathematics and Natural Sciences of UNJ.

References [1]

Wang, Xin-Jiu.; Zhou, Qi-Feng. Liquid Crystalline Polymers; World Scientific Publishing Co. Pte. Ltd, 2004; pp 19-20. [2] Haruhisa, A.; Mallia, V. A.; Nobuyuki, T. Synthesis, Liquid-Crystalline Properties, and Photo-optical Studies of Photoresponsive Oligomeric Mesogens as Dopants in a Chiral Glassy Liquid Crystal. Adv. Funct. Mater 2006, 16, 477-484 [3] Chen, T. Thermo-Optical Properties of Polymer Dispersed Liquid Crystals. Thesis of School of Applied Sciences Science, Engineering and Technology Portfolio RMIT University, 2007. [4] Zhou Y.; Briand, V.A.; Sharma, N.; Ahn, S.-K; Kasi, R.M. Review Polymers Comprising Cholesterol: Synthesis, Self-Assembly and Applications. Materials 2009, 2, 636-660. [5] Madhusudana, Recent Advances in Thermotropic Liquid Crystals, Special Section: Soft Condensed Matter. Current Science 2001, 80(8), 1018. [6] Afrizal, M. H.; Riswoko, A. Synthesis and Their Thermotropic Liquid Crystalline Cholesteryl Acrylate Behaviour by Polarizing Optical Microscopy, Proceeding of the QiR FTUI, 2011. [7] Merlo, A. A.; Olga, M. S.; Ritter, F. V.; Pereira, C. H. V.; da Silveira, N. P. J. Braz. Chem. Soc. 2001, 12(2), 184-191. [8] Jean-d’Amour, K. T.; Grindley, T. B. Organic Letters 2011, 13(12), 2988-2991 [9] T. Mihara, T. Uedaira, N. Koide, Fixation of Cholesteric Helical Structure by the Photopolymerization of A Cholesteryl Derived Monomer. Liquid Crystals 2002, 26(6), 855-861. [10] The Chemicalbook website. [Online]. Available: http://www.chemicalbook.com. [11] OBADOVIC Dusanka Z.; VAJDA Aniko; GARIC Maya; BUBNOV A.; HAMPLOVA Vera; KASPAR M.; FODOR-CSORBA Katalin., Thermal Analysis and X-Ray Studies of Chiral Ferroelectric Liquid Crystalline Materials and Their Binary Mixtures. Journal of Thermal Analysis and Calorimetry 2005, 82, 519-523.