A comparison of different experimental methods for investigating the mechanical properties of plane polysiloxane membranes and capsule walls

Abstract

In this publication we systematically compared the surface rheological properties of different polysiloxane capsule membranes with planar cross-linked films of the same chemical composition. We performed interfacial rheological measurements and different experiments of the capsule deformation in shear and centrifugal fields. In a series of experiments we determined the surface shear and Young's moduli of the polysiloxane membranes. These investigations allowed us to calculate the two-dimensional Poisson ratio of the viscoelastic polysiloxane shells. We also compared the yield values of the capsule deformation D_max and the maximal shear strain γ_max, which describe the limits of the linear viscoelastic response. In the regime of large centrifugal forces, we observed a new capsule bursting mechanism. For small deformations, where the membranes showed linear-viscoelastic properties we found a very good agreement between measurements and theoretical predictions.