The bowtie-shaped deformation isotherm of superhydrophobic cylindrical mesopores

Loïc Michel (1) , Lukas Ludescher (2) , Viviana Cristiglio (3) , Elisabeth Charlaix (1) , Oskar Paris (2) , Cyril Picard (1)

1 LIPhy - Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères]
2 MUL - Montanuniversität Leoben
3 ILL - Institut Laue-Langevin

Deformation of superhydrophobic cylindrical mesopores is studied during a cycle of forced water filling and spontaneous drying by in situ small-angle neutron scattering. A high pressure set up is put forward to characterize the deformation of ordered mesoporous silanized silica up to 80 MPa. Strain isotherms of individual pores are deduced from the shift of the Bragg spectrum associated to the deformation of the hexagonal pore lattice. Due to their superhydrophobic nature, pore walls do not cover with a pre-wetting film. This peculiarity gives the ability to use a simple mechanical model to describe both filled and empty pore state without the pitfall of disjoining pressure effects. By fitting our experimental data with this model we measured both the Young's modulus and the Poisson ratio of the nanometric silica wall. The measurement of this later parameter constitutes a specificity offered by superhydrophobic nanopores with respect to hydrophilic ones.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Matière Molle [cond-mat.soft]; Mécanique des matériaux [physics.class-ph]

Loïc Michel, Lukas Ludescher, Viviana Cristiglio, Elisabeth Charlaix, Oskar Paris, et al.. The bowtie-shaped deformation isotherm of superhydrophobic cylindrical mesopores. Langmuir, 2022, 38 (1), pp.211-220. ⟨10.1021/acs.langmuir.1c02427⟩. ⟨hal-03630263⟩