Nanoscale buckling deformation in layered copolymer materials

Ali Makke (1, 2) , Michel Perez (1) , O. Lame (1) , Jean-Louis Barrat (3)

1 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
2 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures
3 LIPhy - Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères]

In layered materials, a common mode of deformation involves buckling of the layers under tensile deformation in the direction perpendicular to the layers. The instability mechanism, which operates in elastic materials from geological to nanometer scales, involves the elastic contrast between different layers. In a regular stacking of "hard" and "soft" layers, the tensile stress is first accommodated by a large deformation of the soft layers. The inhibited Poisson contraction results in a compressive stress in the direction transverse to the tensile deformation axis. The hard layers sustain this transverse compression until buckling takes place and results in an undulated structure. Using molecular simulations, we demonstrate this scenario for a material made of triblock copolymers. The buckling deformation is observed to take place at the nanoscale, at a wavelength that depends on strain rate. In contrast to what is commonly assumed, the wavelength of the undulation is not determined by defects in the microstructure. Rather, it results from kinetic effects, with a competition between the rate of strain and the growth rate of the instability. http://www.pnas.org/content/early/2011/12/23/1111367109.abstract

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Ali Makke, Michel Perez, O. Lame, Jean-Louis Barrat. Nanoscale buckling deformation in layered copolymer materials. Proceedings of the National Academy of Sciences of the United States of America, 2011, pnas.1111367109. ⟨10.1073/pnas.1111367109⟩. ⟨hal-00655988⟩