Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures

• Autorzy: Inglot K. , Martyński T. , Bauman D.
• Języki publikacji: EN

Abstrakty

EN

A study of azo dye/liquid crystal mixtures in monolayers formed at air-water (Langmuir films) and air-solid substrate (Langmuir-Blodgett films) interfaces was performed. Three azo dyes with various molecular structure and two liquid crystal materials: 4-octyl-4'-cyanobiphenyl (8CB) and trans-4-octyl(4'-cyanophenyl)-cyclohexane (8PCH) were used. The morphology of Langmuir films was monitored by means of a Brewster angle microscope (BAM). Moreover, a surface pressure and electronic absorption spectra of the monolayer spread on the water surface of dye/liquid crystal mixtures as a function of a mean molecular area were simultaneously recorded. In addition, the absorption for Langmuir-Blodgett films deposited on quartz plates was measured. Information about intermolecular interactions in the mixtures of the nonamphiphilic dye and the liquid crystal with polar terminal group was obtained. Conclusions about the formation of self-aggregates between dye molecules have been drawn. The influence of the dye molecular structure and its concentration on aggregates' geometry was found.

Słowa kluczowe

EN

Langmuir film; Langmuir-Blodgett film; azo dye; liquid crystal; electronic absorption

• Wydawca: Stowarzyszenie Elektryków Polskich ; Polska Akademia Nauk ; Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
• Czasopismo: Opto-Electronics Review
• Rocznik: 2009
• Tom: Vol. 17, No. 2
• Strony: 120--128
• Opis fizyczny: Bibliogr. 20 poz., wykr., il.

Twórcy

autor

Inglot K.

autor

Martyński T.

autor

Bauman D.

• Faculty of Technical Physics, Poznań University of Technology, 13A Nieszawska Str., 60-965 Poznań, Poland

Bibliografia

• [1] Organic Molecular Aggregates: Electronic Excitation and Interaction Processes. Edited by P. Reineker, H. Haken, and H. C. Wold, Springer, Berlin, 1983.
• [2] T. Kawai, J. Umemura, and T. Takenaka: UV absorption of azobenzene-containing long-chain fatty acids and their barium salts in spread monolayers and Langmuir-Blodgett films. Langmuir 5, 1378-1383, 1989.
• [3] T. Martyński and J. Miyake: Langmuir-Blodgett films of dichroic dyes oriented by liquid crystal. Supramol. Sci. 5, 643-647, 1998.
• [4] K. Inglot, A. Kaleta, T. Martyński, and D. Bauman: Molecular aggregation in Langmuir-Blodgett films of azo dye/liquid crystal mixtures. Dyes Pigments 77, 303-314, 2008.
• [5] Side Chain Liquid Crystal Polymers, edited by C.B. Mc Ardle, Blackie, Glasgow, 1984.
• [6] G. Roberts, Langmuir-Blodgett Films, Plenum Press, New York, 1990.
• [7] A. Ulman, An Introduction to Ultrathin Organic Films-from Langmuir-Blodgett to Self-Assembly, Academic Press, New York, 1991.
• [8] M. C. Petty, Langmuir-Blodgett Films - An Introduction, Cambridge University Press, Cambridge, 1996.
• [9] J. Xue, C. S. Jung, and M. W. Kim: Phase transitions of liquid crystal films on an air-water interface. Phys. Rev. Lett. 69, 474-477, 1992.
• [10] M. C. Friedenberg, G. G. Fuller, C. Frank, and C. R. Robertson: Formation of bilayer disks and two-dimensional foams on a collapsing/expanding liquid-crystal monolayer. Langmuir 10, 1251-1256, 1994.
• [11] M. N. G. de Mul and J. A. Mann jr.: Multilayer formation in thin films of thermotropic liquid crystals at the air-water interface. Langmuir 10, 2311-2316, 1994.
• [12] T. Martyński, R. Hertmanowski, and D. Bauman: Molecular organization in two dimensional films of liquid crystalline mixtures. III. Langmuir films of binary mixtures of liquid crystal materials with -CN or -NCS group. Liq. Cryst. 29, 99-105, 2002.
• [13] K. Inglot, T. Martyński, and D. Bauman: Influence of the alkyl chain length of some mesogenic molecules on the Langmuir film formation ability. Liq. Cryst. 33, 855-864, 2006.
• [14] D. Hoenig and D. Moebius: Direct visualization of monolayers at the air-water interface by Brewster angle microscopy. J. Phys. Chem. 95, 4590-4592, 1991.
• [15] A. Biadasz, K. Łabuszewska, E. Chrzumnicka, E. Michałowski, T. Martyński, and D. Bauman: Spectral properties of some fluorescent dyes in two-dimensional films formed by means of Langmuir-Blodgett technique. Dyes Pigments 74, 598-607, 2007.
• [16] M. Kasha, H. R. Rawls, and M. Ashraf El-Bayoumi: The exciton model in molecular spectroscopy. Pure Appl. Chem. 11, 371-392, 1965.
• [17] D. Moebius: Scheibe aggregates. Adv. Mater. 7, 437-444, 1995.
• [18] E. Johnson, R. Aroca, and Y. Nagao: Electronic and vibrational spectra of films and Langmuir-Blodgett monolayers of N-octyl-3,4,perylenedicarboximide. J. Phys. Chem. 95, 8840-8843, 1991.
• [19] R. Hertmanowski, T. Martyński, and D. Bauman: Alignment of molecules in Langmuir and Langmuir-Blodgett films of binary mixtures of 3,4,9,10-tetra-(n-alkoxy-carbonyl)-perylenes with a liquid crystal. J. Mol. Struct. 741, 201-211, 2005.
• [20] A. Biadasz, T. Martyński, R. Stolarski, and D. Bauman: Molecular organization in binary mixtures of derivatives of naphthalenebicarboxylic acid and naphthoylene-benzimidazole with a liquid crystal in two-dimensional layers. II. Langmuir-Blodgett films. Liq. Cryst. 33, 307-319, 2006.