Hostname: page-component-cd9895bd7-gxg78 Total loading time: 0 Render date: 2024-12-23T12:46:48.207Z Has data issue: false hasContentIssue false
  • English
  • Français

Optical properties of high-performance liquid crystal–xerogel microcomposite electro-optical film

Published online by Cambridge University Press:  21 March 2012

Martin Timusk ,
Martin Järvekülg ,
Aigi Salundi ,
Rünno Lõhmus ,
Silver Leinberg ,
Ilmar Kink  and
Kristjan Saal
Martin Timusk*
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
Martin Järvekülg
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
Aigi Salundi
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
Rünno Lõhmus
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
Silver Leinberg
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
Ilmar Kink
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
Kristjan Saal
Affiliation:
Institute of Physics, University of Tartu; and Estonian Nanotechnology Competence Center, Tartu 51014, Estonia
*
a)Address all correspondence to this author. e-mail: [email protected]
Get access

Abstract

Electro-optical films composed of liquid crystal (LC) microdroplets encapsulated in an organically modified xerogel matrix were prepared by combined sol-gel and phase separation methods. The incorporation of a titanium alkoxide in the synthesis process as a co-precursor to silicon alkoxides was achieved without any destructive influence on the macroscopic LC phase separation. The consequent increase in the refractive index of the matrix satisfied the important criteria for high-performance films. The prepared films exhibit an outstanding 75.9% change in transmittance as an electric field is applied. An original setup was developed that enables the measurement of the film transmittance versus applied voltage at different temperatures over the full visible and near-infrared (near-IR) spectral range. For the first time, the relationship between these important characteristics (i.e., change in transmittance versus wave length versus temperature) was measured for a xerogel-dispersed LC composite film. The maximum of the curve increased and moved from the IR to the midvisible range with increasing temperature, achieving its maximum at 25.2 °C and 551 nm.

Keywords

Sol-gelLiquid crystalOptical properties
Type
Articles
Information
Journal of Materials Research , Volume 27 , Issue 9 , 14 May 2012 , pp. 1257 - 1264
Copyright
Copyright © Materials Research Society 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1.Tanev, P.T., Chibwe, M., and Pinnavaia, T.J.: Titanium-containing mesoporous molecular sieves for catalytic oxidation of aromatic compounds. Nature 368, 321 (1994).CrossRefGoogle ScholarPubMed
2.Almeida, R.M. and Portal, S.: Photonic band gap structures by sol–gel processing. Curr. Opin. Solid State Mater. Sci. 7, 151 (2003).CrossRefGoogle Scholar
3.De Vos, R.M. and Verweij, H.: High-selectivity, high-flux silica membranes for gas separation. Science 279, 1710 (1998).CrossRefGoogle Scholar
4.Sekuli’c, J., ten Elshof, J.E., and Blank, D.H.A.: Separation mechanism in dehydration of water/organic binary liquids by pervaporation through microporous silica. J. Memb. Sci. 254, 267 (2005).CrossRefGoogle Scholar
5.Baetens, R., Jelle, B.P., and Gustavsen, A.: Aerogel insulation for building applications: A state-of-the-art review. Energy Build. 43, 761 (2011).CrossRefGoogle Scholar
6.Wang, S-H., Choua, T-C., and Liu, C-C.: Nano-crystalline tungsten oxide NO2 sensor. Sens. Actuators B Chem. 94, 343 (2003).CrossRefGoogle Scholar
7.Zayat, M. and Levy, D.: Surface organic modifications and the performance of sol-gel derived gel-glass dispersed liquid crystals (GDLCs). Chem. Mater. 15, 2122 (2003).CrossRefGoogle Scholar
8.Sakka, S., Langlet, M., and Kamiya, K.: Handbook of Sol-gel Science and Technology: Processing, Characterization and Applications, Vol. 1 (Kluwer Academic Publishers, Norwell, 2005), Ch. 2–5.Google Scholar
9.Scherer, G.W.: Theory of drying. J. Am. Ceram. Soc. 73, 3 (1990).CrossRefGoogle Scholar
10.Yusuf, M.M., Imai, H., and Hirashima, H.: Preparation of mesoporous TiO2 thin films by surfactant templating. J. Non Cryst. Solids 285, 90 (2001).CrossRefGoogle Scholar
11.Imhof, A. and Pine, D.J.: Ordered macroporous materials by emulsion templating. Nature 389, 948 (1997).CrossRefGoogle Scholar
12.Stein, A.: Sphere templating methods for periodic porous solids. Microporous Mesoporous Mater. 44–45, 227 (2001).CrossRefGoogle Scholar
13.Nakanishi, K. and Tanaka, N.: Sol-gel with phase separation. Hierarchically porous materials optimized for high-performance liquid chromatography separations. Acc. Chem. Res. 40, 863 (2007).CrossRefGoogle ScholarPubMed
14.Nakanishi, K.: Sol–gel process of oxides accompanied by phase separation. Bull. Chem. Soc. Jpn. 79, 673 (2006).CrossRefGoogle Scholar
15.Nakanishi, K. and Soga, N.: Phase separation in gelling silica-organic polymer solution: Systems containing poly(sodium styrenesulfonate). J. Am. Ceram. Soc. 74, 2518 (1991).CrossRefGoogle Scholar
16.Otón, J.M., Serrano, A., Cerna, C.J., and Levy, D.: Glass dispersed liquid crystals. Liq. Cryst. 5, 733 (1991).CrossRefGoogle Scholar
17.Levy, D., Cerna, C.S., and Otón, J.M.: Preparation of electro-optical active liquid crystal microdomains by the sol-gel process. Mater. Lett. 10, 470 (1991).CrossRefGoogle Scholar
18.Chang, W-P., Whang, W-T., and Wong, J-C.: Electrooptic characteristics of amino-gel-glass-dispersed liquid crystal and its matrix formation. Jpn. J. Appl. Phys. 34, 1888 (1995).CrossRefGoogle Scholar
19.Drzaic, P.S.: Liquid Crystal Dispersions (World Scientific, Teaneck, NJ, 1995) pp. 183–353.CrossRefGoogle Scholar
20.Schubert, U.: Chemical modification of titanium alkoxides for sol–gel processing. J. Mater. Chem. 15, 3701 (2005).CrossRefGoogle Scholar
21.Schwartz, R.W., Voigt, J.A., Tuttle, B.A., Payne, D.A., Reichert, T.L., and DaSalla, R.S.: Comments on the effects of solution precursor characteristics and thermal processing conditions on the crystallization behavior of sol-gel derived lead zirconate titanate thin films. J. Mater. Res. 12, 444 (1997).CrossRefGoogle Scholar
22.Hung, K.M., Hsieh, C.S., Yang, W.D., and Tsai, H.J.: Synthesis of nanometric-sized barium titanate powders using acetylacetone as the chelating agent in a sol-precipitation process. J. Electron. Mater. 36, 245 (2007).CrossRefGoogle Scholar
23.Ren, J., Li, Z., Liu, S., Xing, Y., and Xie, K.: Silica–titania mixed oxides: Si–O–Ti connectivity, coordination of titanium, and surface acidic properties. Catal. Letters 124, 185 (2008).CrossRefGoogle Scholar
24.Nath, A., Mandal, P., Paul, S., and Chaudhury, B.: Determination of molecular properties of some polar mesogenic compounds. Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. A 281, 57 (1996).CrossRefGoogle Scholar
25.Timusk, M., Järvekülg, M., Lõhmus, R., Kink, I., and Saal, K.: Sol–gel matrix dispersed liquid crystal composite: Influence of methyltriethoxysilane precursor and solvent concentration. Mater. Sci. Eng. B 172, 1 (2010).CrossRefGoogle Scholar
26.Castellon, E., Zayat, M., and Levy, D.: Molecular configuration transitions of a nematic liquid crystal encapsulated in organically modified silicas. Phys. Chem. Chem. Phys. 11, 6234 (2009).CrossRefGoogle ScholarPubMed
27.Kumar, S.: Liquid Crystals: Experimental Study of Physical Properties and Phase Transitions (Cambridge University Press, Cambridge, UK, 2000).Google Scholar
28.Boussoualem, M., Roussel, F., and Ismaili, M.: Thermophysical, dielectric, and electro-optic properties of nematic liquid crystal droplets confined to a thermoplastic polymer matrix. Phys. Rev. E: Stat. Nonlin. Soft Matter Phys. 69, 031702 (2004).CrossRefGoogle ScholarPubMed
29.Aliev, F.M.: Molecular and collective relaxation in deeply supercooled confined liquid crystal. J. Non Cryst. Solids 307–310, 489 (2002).CrossRefGoogle Scholar