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Mechanical properties of monodomain nematic side-chain liquid-crystalline elastomers with homeotropic and in-plane orientation of the director

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Abstract

We present the first study of the shear mechanical properties of monodomain nematic side-chain liquid-crystal elastomers (SCLCEs) prepared by cross-linking with UV irradiation a nematic side-chain liquid-crystal polymer oriented with an electric or a magnetic field. Their elastic behavior was studied in the dry, swollen and stretched states, in order to check the various theoretical descriptions of these systems. The shear measurements taken on the dry samples show that the shear anisotropy is much smaller than that of the usual twice cross-linked samples oriented by a mechanical stretching of the network formed after the first cross-linking step, demonstrating that the elasticity of the networks strongly depends on the preparation procedure used. The shear experiments performed on the swollen state of these two different types of elastomers reveal that the elasticity of the network is Gaussian for the elastomers oriented with the electric or the magnetic field, and non-Gaussian for the elastomers oriented with the usual stretching procedure. The analysis of the stress-strain curves of both types of elastomers with the neoclassical model based on Gaussian rubber elasticity confirms the Gaussian and non-Gaussian nature of their elasticity. The shear experiments performed as a function of the elongation of the homeotropically oriented elastomer when the shear is applied in a direction parallel to the elongation, do not show the decrease of the associated shear modulus, which is theoretically expected when the strain approaches the threshold value marking the beginning of the elastic plateau. However, the observation of this effect could be prevented by possible small misalignments of the director, as suggested by a calculation presented in one of the theories describing this effect.

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References

  1. J. Küpfer, H. Finkelmann, Macromol. Chem. Phys. 195, 1353 (1994).

    Article  Google Scholar 

  2. See, for instance, M. Warner, E.M. Terentjev, Liquid Crystal Elastomers (Oxford University Press, Oxford, 2003).

  3. H.R. Brand, H. Pleiner, P. Martinoty, Soft Matter 2, 182 (2006).

    Article  ADS  Google Scholar 

  4. P.G. de Gennes, in Liquid Crystals of One- and Two-Dimensional Order, edited by W. Helfrich, G. Heppke (Springer, Berlin, 1980) p. 231

  5. M. Warner, P. Bladon, E.M. Terentjev, J. Phys. II 4, 93 (1994).

    Article  Google Scholar 

  6. P. Olmsted, J. Phys. II 4, 2215 (1994).

    Article  Google Scholar 

  7. L. Golubovic, T.C. Lubensky, Phys. Rev. Lett. 63, 1082 (1989).

    Article  ADS  Google Scholar 

  8. G. Verwey, M. Warner, Macromolecules 28, 4303 (1995).

    Article  ADS  Google Scholar 

  9. M. Warner, J. Mech. Phys. Solids 47, 1355 (1999).

    Article  ADS  MATH  MathSciNet  Google Scholar 

  10. G. Verwey, M. Warner, E.M. Terentjev, J. Phys. II 6, 1273 (1996).

    Article  Google Scholar 

  11. G. Verwey, M. Warner, Macromolecules 30, 4189 (1997).

    Article  ADS  Google Scholar 

  12. G. Verwey, M. Warner, Macromolecules 30, 4196 (1997).

    Article  ADS  Google Scholar 

  13. P. Bladon, E.M. Terentjev, M. Warner, Phys. Rev. E 47, R3838 (1993).

    Article  ADS  Google Scholar 

  14. S. Conti, A. DeSimone, G. Dolzmann, Phys. Rev. E 66, 061710 (2002).

    Article  ADS  Google Scholar 

  15. E.M. Terentjev, M. Warner, Eur. Phys. J. E 4, 343 (2001).

    Article  Google Scholar 

  16. S.M. Clarke, A.R. Tajbakhsh, E.M. Terentjev, M. Warner, Phys. Rev. Lett. 86, 4044 (2001).

    Article  ADS  Google Scholar 

  17. P. Martinoty, P. Stein, H. Finkelmann, H. Pleiner, H.R. Brand, Eur. Phys. J. E 14, 311 (2004).

    Article  Google Scholar 

  18. D. Rogez, G. Francius, H. Finkelmann, P. Martinoty, Eur. Phys. J. E 20, 369 (2006).

    Article  Google Scholar 

  19. F. Ye, R. Mukhopadhyay, O. Stenull, T.C. Lubensky, Phys. Rev. Lett. 98, 147801 (2007).

    Article  ADS  Google Scholar 

  20. J.S. Biggins, E.M. Terentjev, M. Warner, Phys. Rev. E 78, 041704 (2008).

    Article  ADS  Google Scholar 

  21. A.M. Menzel, H. Pleiner, H.R. Brand, Eur. Phys. J. E 30, 371 (2009).

    Article  Google Scholar 

  22. J.-L. Gallani, L. Hilliou, P. Martinoty, F. Doublet, M. Mauzac, J. Phys. II 6, 443 (1996).

    Article  Google Scholar 

  23. J. Weilepp, P. Stein, N. Aßfalg, H. Finkelmann, P. Martinoty, H.R. Brand, Europhys. Lett. 47, 508 (1999).

    Article  ADS  Google Scholar 

  24. J. Weilepp, J.J. Zanna, N. Aßfalg, P. Stein, L. Hilliou, M. Mauzac, H. Finkelmann, H.R. Brand, P. Martinoty, Macromolecules 32, 4566 (1999).

    Article  ADS  Google Scholar 

  25. P. Stein, N. Aßfalg, H. Finkelmann, P. Martinoty, Eur. Phys. J. E 4, 255 (2001).

    Article  Google Scholar 

  26. J.J. Zanna, P. Stein, J.D. Marty, M. Mauzac, P. Martinoty, Macromolecules 35, 5459 (2003).

    Article  ADS  Google Scholar 

  27. D. Rogez, H. Brandt, H. Finkelmann, P. Martinoty, Macromol. Chem. Phys. 207, 735 (2006).

    Article  Google Scholar 

  28. J.L. Gallani, L. Hilliou, P. Martinoty, P. Keller, Phys. Rev. Lett. 72, 2109 (1994).

    Article  ADS  Google Scholar 

  29. P. Martinoty, L. Hilliou, M. Mauzac, L. Benguigui, D. Collin, Macromolecules 32, 1746 (1999).

    Article  ADS  Google Scholar 

  30. D. Collin, P. Martinoty, Physica A 320, 235 (2003).

    Article  ADS  Google Scholar 

  31. D. Collin, P. Martinoty, Eur. Phys. J. E 19, 87 (2006).

    Article  Google Scholar 

  32. O. Pozo, D. Collin, H. Finkelmann, D. Rogez, P. Martinoty, Phys. Rev. E 80, 031801 (2009).

    Article  ADS  Google Scholar 

  33. D. Collin, G.K. Auernhammer, O. Gavat, P. Martinoty, H.R. Brand, Macromol. Rapid Commun. 24, 737 (2003).

    Article  Google Scholar 

  34. G.K. Auernhammer, D. Collin, P. Martinoty, J. Chem. Phys. 124, 204907 (2006).

    Article  ADS  Google Scholar 

  35. D. Collin, P. Lavalle, J. Mendez Garza, J.C. Voegel, P. Schaaf, P. Martinoty, Macromolecules 37, 10195 (2004).

    Article  ADS  Google Scholar 

  36. F. Brömmel, H. Finkelmann, to be published

  37. A. Lebar, Z. Kutnjak, S. Zumer, H. Finkelmann, A. Sanchez-Ferrer, B. Zalar, Phys. Rev. Lett. 94, 197801 (2005).

    Article  ADS  Google Scholar 

  38. P.G. de Gennes, C. R. Acad. Sci. (Paris), Sér. B 281, 101 (1975).

    Google Scholar 

  39. A.M. Menzel, H. Pleiner, H.R. Brand, J. Appl. Phys. 105, 013503 (2009).

    Article  ADS  Google Scholar 

  40. The chain anisotropy r of the samples prepared by E- or H-field is much smaller than the chain anisotropy of the usual samples prepared by mechanical stretching, and is very similar to the chain anisotropy of the sample oriented by wall effect 46. F. Brömmel, private communication.

  41. L.R.G. Treloar, The Physics of Rubber Elasticity (Clarendon Press, Oxford, 1949).

  42. The stress-strain measurements were performed by F. Brömmel

  43. r = 1.26. F. Brömmel, private communication

  44. H. Finkelmann, private communication

  45. As suggested by one of the referees, the discontinuity in slope of the stress-strain curve around the threshold λ1 (instead of the rounding observed for our sample or for the sample of 46) is the necessary condition for the vanishing of \(\tilde C_5\) at λ1. This suggestion can be checked by the light scattering experiments of [47, 48] revealing the existence of a dynamic soft mode associated with the fluctuations of the director, which, according to the theories, must appear concomitantly with the vanishing of \(\tilde C_5\). However, the slope of the stress-strain curve (see, for example, fig. 12 of the present paper) does not show the discontinuity around λ1 expected by the referee. The discontinuity in slope is therefore not required for the observation of the soft mode

  46. K. Urayama, R. Mashita, I. Kobayashi, T. Takigawa, Macromolecules 40, 7765 (2007).

    Google Scholar 

  47. A. Petelin, M. Copic, Phys. Rev. Lett. 103, 077801 (2009).

    Article  ADS  Google Scholar 

  48. A. Petelin, M. Copic, Phys. Rev. E 82, 011703 (2010).

    Article  ADS  Google Scholar 

  49. The error on λ1 (1.05 < λ1 < 1.07 at T = 75 °C and T = 60 °C) is deduced via eq. (3) from the error on α ((α = 3.9 ± at 0.8)% at T = 75 °C, α = (6.3 ± 1.2)% at T = 60 °C).

  50. The error on λ1 (1.072 < λ1 < 1.092) is deduced via eq. (3) from the error on α (α = (11.7 ± 1.2)%).

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  1. UPR 22, CNRS/UDS, Institut Charles Sadron, 23 rue du Loess, 67034, Strasbourg, France

    D. Rogez & P. Martinoty

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  1. D. Rogez
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  2. P. Martinoty
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Correspondence to P. Martinoty.

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Rogez, D., Martinoty, P. Mechanical properties of monodomain nematic side-chain liquid-crystalline elastomers with homeotropic and in-plane orientation of the director. Eur. Phys. J. E 34, 69 (2011). https://doi.org/10.1140/epje/i2011-11069-8

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  • DOI: https://doi.org/10.1140/epje/i2011-11069-8

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