We have developed a simple technique for the fabrication of polymer nanotubes with a monodisperse size distribution and uniform orientation. When either a polymer melt or solution is placed on a substrate with high surface energy, it will spread to form a thin film, known as a precursor film, similar to the behavior of low molar mass liquids (1, 2). Similar wetting phenomena occur if porous templates are brought into contact with polymer solutions or melts: A thin surface film will cover the pore walls in the initial stages of wetting. This is because the cohesive driving forces for complete filling are much weaker than the adhesive forces. Wall wetting and complete filling of the pores thus take place on different time scales. The latter is prevented by thermal quenching in the case of melts or by solvent evaporation in the case of solutions, thus preserving a nanotube structure. If the template is of monodisperse size distribution, aligned or ordered, so are the nanotubes, and ordered polymer nanotube arrays can be obtained if the template is removed. Any melt-processible polymer, such as polytetrafluoroethylene (PTFE), blends, or multicomponent solutions can be formed into nanotubes with a wall thickness of a few tens of nanometers. Owing to its versatility, this approach should be a promising route toward functionalized polymer nanotubes. We used ordered porous alumina and oxidized macroporous silicon templates with narrow pore size distribution (3). Extended regular pore arrays were prepared by lithography. The pores are well-defined, straight, with a smooth inner surface and with diameters D P between 300 and 900 nm. To process melts, we placed the polymer on a pore array at a temperature well above its glass transition temperature, in

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A perfect two-dimensional porous alumina photonic crystal with 500 nm interpore distance was fabricated on an area of 4 cm 2 via imprint methods and subsequent electrochemical anodization. By comparing measured reflectivity with theory, the refractive indices in the oxide layers were determined. The results indicate that the porous alumina structure is composed of a duplex oxide layer: an inner oxide layer consisting of pure alumina oxide of 50 nm in thickness, and an outer oxide layer of a nonuniform refractive index. We suggest that the nonuniform refractive index of the outer oxide arises from an inhomogeneous distribution of anion species concentrated in the intermediate part of the outer oxide.

Dual-wavelength reflection interference contrast microscopy (DW-RICM) is established as a microinterferometric technique to measure absolute optical distances between transparent planar substrates and hard or soft surfaces such as colloidal beads or artificial and biological membranes, which hover over the substrate. In combination with a fast image processing algorithm the technique was applied to analyze the trajectories of colloidal beads sedimenting under gravity. As the beads approach the surface of the substrate, they slow down because of hydrodynamic coupling of the bead motion to the substrate. The effective surface friction coefficients were measured as a function of the absolute distance of the beads from the surface. The height dependence of the friction coefficient was found to be in quantitative agreement with previous theoretical predictions. Furthermore, we demonstrate that the DW-RICM technique allows the determination of the height of membranes above substrates and the amplitude and direction of height fluctuations. Without any further need to label the membrane the unambiguous reconstruction of the surface profile of soft surfaces is possible.

We present an experimental system suitable for producing spherical crystals and for observing the distribution of lattice defects (disclinations and dislocations) on a significant fraction (50%) of the sphere. The introduction of fluorescently labeled particles enables us to determine the location and orientation of grain boundary scars. We find that the total number of scars and the number of excess dislocations per scar agree with theoretical predictions and that the geometrical centers of the scars are roughly positioned at the vertices of an icosahedron.