Morphology of self-assembled polystyrene particle layers has been modified by reactive ion etching. The etched layers have two-dimensional periodic structures in submicron scale, the period of which is determined by the initial size of the particles, and the shape of the etched particles has been gradually changed to a thinner ellipsoid depending on the etching time. Resonant phenomenon between incident light and electromagnetic eigenmodes of the photonic band of the etched layers has been observed in transmission measurement. The resonant frequencies have gradually shifted according to the etching time, i.e., the photonic band structure of the layers has been successfully modified. Various kinds of applications can be expected due to the electromagnetic resonant phenomenon and the characteristic surface structure of the layers.

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The Span 40 (sorbitan monooleate)/Tween 40 (polyoxyethylene sorbitan monolaurate) system gives faceted vesicles with angular surfaces, rather than spherical vesicles. Herein, a continuous and facile preparation method, based on the subcritical water-assisted emulsification and solvent diffusion, was presented to yield faceted vesicles with two major and minor axes (Type A) and vesicles closer to a polyhedron (Type B). Type A, rather than Type B, vesicles were likely to be formed. From the measurements concerning ζ-potential, membrane fluidity, and the polarization environment of the membranes, faceted vesicles could be obtained at 0.25 wt% of the surfactant concentration. The phase-separated behavior of Span 40 and Tween 40 within vesicle membranes could explain the structural feature of faceted vesicles and calcein leakage behavior. The significant advantage is that Type A vesicles would be utilized as alternative drug carriers for others with low encapsulation efficiency, although the present technical limitations cause difficulty in the selective formation of Type A and B vesicles and the selection of adequate solvent to accelerate the solvent diffusion step.

A phase separation in a dispersion of two kinds of particles has recently been reported to result from entropic interactions between particles and between particles and surfaces in closed spaces. In many cases, the phase separation took place localization of large particles in the vicinity of a compartment. However, phase separation in closed systems has been limited to systems in which the number of small particles was much larger than the number of large particles. In contrast, we prepared giant vesicles (GVs) in which the volume fraction of large particles was higher than that of the small particles. As a result, we observed a new phenomenon in which small particles localized spontaneously and stably in the vicinity of the vesicular membrane. To explain this phenomenon theoretically, we assumed that an equilibrium osmotic pressure was realized between an outer phase containing a relatively large number of small particles and another inner phase. The osmotic pressure was estimated from the free energy change due to the excluded-volume effect. There was good agreement between the distribution ratio of the number of large and small particles in the phases calculated from fluorescent microscopy images and the prediction of the osmotic equilibrium model.