Nonlinear Analysis of Stripe Textures in Hexagonal Lyotropic Mesophases

P. Oswald , J. Géminard , L. Lejcek , L. Sallen

Fan-shaped textures of hexagonal mesophases of lyotropic systems are often striated. These striations are due to a thermomechanical undulation of the columns. We measure their wavelength and amplitude in the lyotropic mixture C12EO6+water. By comparing these measurements to the theoretical predictions in the strongly nonlinear regime (our model is generalization of the model of Singer [17] to columnar phases), we find that the penetration length $\lambda=\sqrt{K/B}$ is of the order of 40 Å (where B is the compressibility modulus of the hexagonal array and K the curvature modulus of the columns). This value is in qualitative agreement with that found by using X-rays [11] or the grain-boundary method [10]. In addition, we find that the shear elastic modulus μ of the hexagonal array is 5 to 10 times smaller than B, in agreement with X-ray experiments [16].

Domaines: Articles anciens

P. Oswald, J. Géminard, L. Lejcek, L. Sallen. Nonlinear Analysis of Stripe Textures in Hexagonal Lyotropic Mesophases. Journal de Physique II, 1996, 6 (2), pp.281-303. ⟨10.1051/jp2:1996182⟩. ⟨jpa-00248298⟩