Adhesion induced buckling of spherical shells

Deformation of a spherical shell adhering onto a rigid substrate due to van der Waals attractive interaction is investigated by means of numerical minimization of the sum of the elastic and adhesion energies. The conformation of the deformed shell is governed by two dimensionless parameters C-s/epsilon and C-b/epsilon, where C-s and C-b are respectively the stretching and the bending constants, and epsilon is the depth of the van der Waals potential. As a function of Cb/epsilon, we find both continuous and discontinuous buckling transitions for small and large C-s/epsilon, respectively, which is analogous to van der Waals fluids or gels. Some scaling arguments are employed to explain the adhesion induced buckling transition.