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Defects in Liquid-Crystalline Polymers

Published online by Cambridge University Press:  29 November 2013

M. Kléman
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The properties of imperfections (or defects) of the atomic or molecular order in condensed matter can be conveniently described under two headings: (1) Topological properties—Defects break a specific symmetry of the ordered system at a local scale, that is, along a point defect, a line defect (a dislocation or a disclination), or a surface defect (a wall). (2) Elastic properties—Defects are sources of two types of distortions of the order: long-range distortions, which depend crucially on the broken symmetry but also on the material constants, and short-range distortions in the “core” region of the defect where the order parameter of the ordered phase is broken. These distortions are irreversible in the sense that defects appear during plastic deformation (in solids) or rheological flow (in liquid crystals).

To illustrate this classification, let us recall the example of dislocation lines in solids. These defects break translational symmetries (henceforth a dislocation is defined topologically by the translation b it breaks, the so-called Burgers vector). They are at the origin of rather weak, long-range, internal distortions and stresses that depend on the elastic constants (in the region of the good crystal) and rather strong, short-range distortions and stresses in the “core” region, implying a complete rearrangement of the molecular order. These stresses are different in the static and dynamic states, and the shape of the dislocation line, as well as its size, etc., depend on the history of the sample.

In this article, we will focus on defects in liquid-crystalline polymers. A synthetic polymer that displays mesomorphic order (intermediate between crystalline and liquid) is usually made of units that are themselves mesogenic and that align coherently when in contact.

Type
Defects in Polymers
Information
MRS Bulletin , Volume 20 , Issue 9 , September 1995 , pp. 23 - 28
Copyright
Copyright © Materials Research Society 1995

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References

1.Friedel, J., Dislocations, 1st ed. (Pergamon Press, Oxford, 1964).Google Scholar
2.Onsager, L., Ann. N.Y. Acad. Sci. 51 (1949) p. 627.CrossRefGoogle Scholar
3.Bernal, J.D. and Fankuchen, L., J. Gener. Physiol. 25 (1941) p. 111.CrossRefGoogle Scholar
4.Frank, F.C., in Liquid Crystals: Their Physics, Chemistry, and Applications, edited by Hilsum, C. and Raynes, E.P. (The Royal Society, London, 1983) p. 1.Google Scholar
5.Voigt-Martin, I.G. and Durst, H., Macromolecules 22 (1989) p. 168.CrossRefGoogle Scholar
6.Frank, F.C., Discuss. Faraday Soc. 25 (1958) p. 1.CrossRefGoogle Scholar
7.Kléman, M., Rep. Prog. Phys. 52 (1989) p. 555.CrossRefGoogle Scholar
8.Liquid Crystallinity in Polymers, edited by Ciferri, A. (VCH, New York, 1991).Google Scholar
9.Meyer, R.B., Philos. Mag. 27 (1973) p. 405; Cladis, P.E. and Kléman, M., J. Phys. Lett. 33 (1972) p. 591.CrossRefGoogle Scholar
10.Bouligand, Y., in Physics of Defects, Les Houches, Section XXXV, NATO ASI, edited by Balian, R., Kléman, M., and Poirier, J.P. (NHPC, Amsterdam, 1982) p. 665.Google Scholar
11.Toulouse, G. and Kléman, M., J. Phys. Lett. 37 (1976) p. L–149; Mermin, N.D., Rev. Mod. Phys. 51 (1979) p. 591; Michel, L., Rev. Mod. Phys. 52 (1982) p. 617.CrossRefGoogle Scholar
12.de Gennes, P.G., The Physics of Liquid Crystals (Clarendon Press, Oxford, 1974); Kléman, M., Points, Lines and Walls (Wiley & Sons, J., Chichester, U.K., 1983).Google Scholar
13.Lee, S.D. and Meyer, R.B., in Liquid Crystallinity in Polymers, edited by Ciferri, A. (VCH Publishers Int., New York, 1991) p. 343.Google Scholar
14.Zasadzinski, J.A.N., Sammon, M.J., Meyer, R.B., Cahoon, M., and Caspar, D.L.D., Mol. Cryst. Liq. Cryst. 138 (1986) p. 211.CrossRefGoogle Scholar
15.Kléman, M., Liébert, L., and Stzrelecki, L., Polymer 24 (1983) p. 295; Mazelet, G. and Kléman, M., Polymer 27 (1986) p. 714; Shiwaku, T., Nakai, A., Hasegawa, H., and Hashimoto, T. , Macromolecules 23 (1990) p. 1,590.CrossRefGoogle Scholar
16.Nye, J.F., Acta Metall. 1 (1953) p. 153.CrossRefGoogle Scholar
17.Hodbell, J. and Windle, A. (private communication).Google Scholar
18.Toulouse, G., J. Phys. Lett. 38 (1977) p. L–37.Google Scholar
19.De'Neve, T., Kléman, M., and Navard, P., J. Phys. II France 2 (1992) p. 187.Google Scholar
20.Friedel, J. and Kléman, M., J. Phys. Colloq. 30 (1969) p. C4–43.Google Scholar
21.Trebin, H-R., Adv. Phys. 31 (1982) p. 195.CrossRefGoogle Scholar
22.Hilbert, D. and Cohn-Vossen, S., Geometry and the Imagination (Chelsea, New York, 1952).Google Scholar
23.Harris, W.F., in Fundamental Aspects of Dislocation Theory, vol. 317 (1) (N.B.S. Spec. Publ.) p. 379; Nabarro, F.R.N., in Fundamental Aspects of Dislocation Theory, vol. 317 (1) (N.B.S. Spec. Publ.) p. 393.Google Scholar
24.Robinson, C. and Beevers, J.C., Discuss. Faraday Soc. 25 (1966) p. 29; Bouligand, Y. and Livolant, F., J. Phys. Lett. 45 (1984) p. 1,899.CrossRefGoogle Scholar
25.Livolant, F., J. Phys. Lett. 48 (1987) p. 1,051; Kléman, M., Phys. Scri. T19 (1988) p. 565.Google Scholar
26.Livolant, F. and Bouligand, Y., Chromosoma 80 (1980) p. 97; Kléman, M., J. Phys. Lett. 46 (1985) p. L723; M. Kléman, J. Phys. Lett. 46 (1985) p. 1,193.CrossRefGoogle Scholar
27.Kiss, G. and Porter, R.S., Mol. Cryst. Liq. Cryst. 60 (1980) p. 267; Marucci, G., Pure Appl. Chem. 57 (1985) p. 1,545; Navard, P., J. Polym. Sci., Polym. Phys. Ed. 24 (1986) p. 435; Moldenaers, P., Fuller, G., and Mewis, J., Macromolecules 22 (1989) p. 960.CrossRefGoogle Scholar
28.Takeuchi, Y., Shuto, Y., and Yamamoto, F., Polymer 29 (1988) p. 605; De'Nève, T., Navard, P., and Kléman, M., J. Rheol. 37 (1993) p. 515.CrossRefGoogle Scholar
29.Millaud, B., Thierry, A., and Skoulios, A., J. Phys. Lett. 39 (1978) p. 1,109; Aldermann, N.J. and Mackley, M.R., Faraday Discuss. Chem. Soc. 79 (1985) p. 149.Google Scholar
30.Marrucci, G. and Maffetone, P.L., Macromolecules 22 (1989) p. 4,076; Larson, R.G. and Öttinger, H.C., Macromolecules 24 (1991) p. 6,270.CrossRefGoogle Scholar
31.Geiger, K. and De'Neve, T., Rheol. Acta 33 (1994) p. 542.CrossRefGoogle Scholar
32.De'Nève, T., Kléman, M., and Navard, P., C.R. Acad. Sci. Paris 316 série II, (1993) p. 1,037; De'Nève, T., Kléman, M., and Navard, P., Macromolecules 28 (1995) p. 1,541.Google Scholar