This measure has been used by Chang and Olbricht (1). It This paper studies the rheological properties of ultrathin aminowas found to be delicate to perform and not very precise. methacrylate membranes that are synthesized at the interface be-Another method which is extensively used for biological tween oil and water. We have measured the kinetics of the crosscells consists of sucking part of the membrane into a microlinking reactions, the zero shear modulus, and the nonlinear pipette and then observing the height of aspiration inside the rheological properties of those two-dimensional networks. The tube for a given depression (2). This method allows the measurements were performed at a planar interface using a special membrane mechanical properties to be evaluated, provided surface rheometer. Once stabilized, the membranes exhibit rubberthere is no slippage between the pipette and the membrane. elastic properties. In addition, we have formed small emulsion droplets using the same type of interfacial polymerization. In order However, the validity of this last hypothesis is often questo get more information on the mechanical properties of the retioned. Finally, another line of approach consists of sussulting microcapsules, we have developed a new experimental pending the capsule in another liquid subjected to flow and technique that consists in measuring the deformation of a capsule measuring the resulting particle deformation under the inin a spinning drop apparatus. A theoretical analysis of the deforfluence of viscous shear forces (1, 3). The problem with mation process allows an interface apparent elastic Young moduthis method is that it is difficult to relate the overall capsule lus to be calculated. From a comparison of the surface shear modudeformation to the intrinsic physical parameters of the partilus with the Young modulus, it is then possible to estimate the cle, unless a fairly complete model of the mechanics of surface Poisson ratio, which is here approximately zero. These the particle is available. Such models either are limited to results point to the existence of area compressible anisotropic spherical capsules and small deformations (4, 5) or are numembranes.