Curvature determination of spinodal interface in a condensed matter system

Laser scanning confocal microscopy has been used to study the time evolution of a three dimensional spatially bicontinuous structure of a phase-separated polymer blend undergoing the late stage of spinodal decomposition, as a model example of condensed matter systems. Both the mean and Gaussian curvatures of the interface between two coexisting phases have been directly measured for the first time from the reconstructed 3D image. The Gaussian curvature is negative, clearly demonstrating that the interface of the bicontinuous structure is anticlastic, while the mean curvature is close to zero. Self-similar growth of the structure is inferred from the time evolution of the average radius of curvature of the interface.