Tunable topographical cellulose for electro-optical liquid crystal cells

• Autorzy: Costa I. , Almeida P. L. , Filip D. , Figueirinhas J. L. , Godinho M. H.
• Konferencja: International Workshop on Liquid Crystals for Photonic ; (26-28.04.2006 ; Gent, Belgium)
• Języki publikacji: EN

Abstrakty

EN

In this work we have used acetoxypropylcellulose (APC) to produce free standing solid films (~60 µm) that were used for assembling electro-optical devices. Thin films were obtained from concentrated lyotropic solutions of cellulose derivatives. Induced by the cast and shearing preparation conditions wrinkles and band textures can be observed in their free-surface plane. In order to eliminate and control these textures we used a process similar to that introduced in literature [1] which consists of storing the films in the same solvent-vapour atmosphere as the solution system. Lyotropic APC liquid crystalline solutions in dymethylacetamide (DMA) with crosslinker were prepared, thin films were obtained by using a shear/casting technique and stored in the solvent-vapour atmosphere until a planar structure was achieved. The dried crosslinked films were analyzed by optical polarised microscopy (POM) and scanning electron microscopy (SEM). The films with different topographies were used to produce optical cells composed by the cellulose derivative film covered on both free surfaces by a layer of the nematic liquid crystal E7 and placed between two transparent conducting substrates. The electro-optical properties of these cells were obtained.

Słowa kluczowe

EN

acetoxypropylcellulose; liquid crystals; PDLC; electrooptical properties

• Wydawca: Stowarzyszenie Elektryków Polskich ; Polska Akademia Nauk ; Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
• Czasopismo: Opto-Electronics Review
• Rocznik: 2006
• Tom: Vol. 14, No. 4
• Strony: 299--303
• Opis fizyczny: Bibliogr. 25 poz., il.

Twórcy

autor

Costa I.

autor

Almeida P. L.

autor

Filip D.

autor

Figueirinhas J. L.

autor

Godinho M. H.

• Dept. Eng. Mecânica, EST/IPS, Campus do IPS, Estefanilha, 2910-761 Setúbal, Portugal

Bibliografia

• 1. S. Suto and K. Suzuki, "Crosslinked hydroxypropyl cellulose films retaining cholesteric liquid crystalline order. I. Effects of cast conditions and heat treatment on the textures and order of films", J. Appl. Polymer Science 55, 139-151 (1995).
• 2. D.G. Gray, "Chiral nematic ordering of polysaccharides", Carbohydrate Polymers 25, 277-284 (1994).
• 3. E. Bianchi, E. Marsano, P. Picasso, L. Matassini, and C. Costa, "Polymeric liquid crystals: cholesteric superstructure from blends of hydroxypropylcellulose esters", Polymers for Advanced Technologies 14, 529-536 (2003).
• 4. J. Giasson, J.F. Revol, D.G. Gray, and J. Stpierr, "Preparation of chiral nematic gels by radiation cross-linking", Macromolecules 24, 1694-1696 (1991).
• 5. H. Hou, A. Reuning, J.H. Wendorff, and A. Greiner, "Tuning of the pitch height of thermotropic cellulose esters", Macromolecular Chemistry and Physics 201, 2050-2054 (2000).
• 6. S.L. Tseng, A. Valente, and D.G. Gray, "Cholesteric liquid crystalline based on (acetoxypropyl)cellulose", Macromolecules 14, 715-719 (1981).
• 7. T. Sato, J. Nakamura, A. Teramoto, and M.M. Green, "Cholesteric pitch of lyotropic polymer liquid crystals", Macromolecules 31, 1398-1405 (1998).
• 8. S.N. Bhadani and D.G. Gray, "Cellulose-based liquid crystalline polymers - esters of (hydroxypropyl)-cellulose", Molecular Crystals and Liquid Crystals 99, 29-38 (1983).
• 9. I. Rusig, M.H Godinho, L. Varichon, P. Sixou, J. Dedier, C. Filliatre, and A.F. Martins, "Optical properties of cholesteric (2-hydroxypropyl)cellulose (HPC) esters", J. Polymer Science: Part B: Polymer Physics 32, 1907-1914 (1994).
• 10. M. Muller and R. Zentel, "Cholesteric phases and films from cellulose derivatives", Macromolecular Chemistry and Physics 201, 2055-2063 (2000).
• 11. G.V. Laivins and D.G. Gray, "Characterization and chain stiffness of (acetoxypropyl)cellulose", Macromolecules 18, 1746-1752 (1985).
• 12. G.V. Laivins and D.G. Gray, "Liquid crystalline", Macromolecules 18, 1753-1759 (1985).
• 13. J.B. Riti, M.T. Cidade, M.H. Godinho, A.F. Martins, and P. Navard, "Shear induced textures of thermotro-pic acetoxypropylcellulose", J. Rheology 41, 1247-1260 (1997).
• 14. H.G. Graighead, J. Cheng, and S. Hackwood, "New display based on electrically induced index matching in an inhomogeneous-medium", Appl. Phys. Lett. 40, 22-24 (1982).
• 15. M.H. Godinho, A.F. Martins, and J.L. Figueirinhas, "Novel PDLC type display based on cellulose derivatives", Liquid Crystals 20, 373-376 (1996).
• 16. J.L. Figueirinhas, P.L. Almeida, and M.H. Godinho, Polysaccharides Structural Diversity and Functional Versatility, New York, Marcel Dekker, 2004.
• 17. M.H. Godinho, J.G. Fonseca, A.C. Ribeiro, L.V. Melo, and P. Brogueira, "Atomic force microscopy study of hydroxypropylcellulose films prepared from liquid crystalline aqueous solutions", Macromolecules 35, 5932-5936 (2002).
• 18. P.J. Sebastio, C. Cruz, C. Pires, A. Ferraz, P. Brogueira, and M.H Godinho, "Anisotropic hydroxypropyl-cellulose films as alignment layers of a bistable ferroelectric device", Liquid Crystals, 29, 1491-1495 (2002).
• 19. P.L Almeida, S. Tavares, A.F. Martins, M.H. Godinho, M.T. Cidade, and J.L. Figueirinhas, "Cross-linked hydroxypropylcellulose films: mechanical behaviour and electro-optical properties of PDLC type cells" Optical Materials 20, 97-100 (2002).
• 20. J.G. Fonseca, M.H. Godinho, and A.C. Ribeiro, "Anchoring properties of a nematic liquid crystal on anisotropic hydroxypropylcellulose films", Liquid Crystals 32, 913-919 (2005).
• 21. X.S. Zhou and Y. Huang, "Temperature dependence of the phase separation in ethyl cyanoethyl cellulose/poly (acrylic acid)/4'-n-pentyl-4-cyano-biphenyl composite films", J. Polymer Science: Polymer Physics Edition 40, 1334-1341 (2002).
• 22. O.A Aphonin, Y.V. Panina, A.B. Pradin, and D.A. Yakolev, "Optical-properties of stretched polymer dispersed liquid crystal films", Liquid Crystals 15, 395-407 (1993).
• 23. I. Amimori, N.V. Priezjev, R.A. Pelvovits, and G.P. Crawford, "Optomechanical properties of stretched polymer dispersed liquid crystal films for scattering polarizer applications", J. Appl. Phys. 93, 3248-3252 (2003).
• 24. D. Filip, I. Costa, J.L. Figueirinhas, and M.H. Godinho, "Anisotropic cellulose derivative matrix for dispersed liquid crystals", Liquid Crystals 33, 109 (2006).
• 25. D. Filip, I. Costa, J.L. Figueirinhas, and M.H. Godinho, "Strain-induced matrix and droplets anisotropic deformation in liquid crystalline cellulose dispersed liquid crystal films", Composite Interfaces 13, 477-486 (2006).