We investigated a gradient of nanometer-sized, self-assembled gold clusters on top of a thin polymer film. Using an advanced characterization method for gradient surfaces and thin films, the characteristic change in cluster height is detected. Our unprecedented approach combining a powerful thin-film characterization method with a micrometer-sized x-ray beam enhances the spatial resolution used thus far by two orders of magnitude. We show that this advanced concept allows for a nondestructive and contact-free reconstruction of the three-dimensional structure and morphology of the nanocluster gradient layer. Despite its change in thickness, the individual clusters’ in-plane shape and distance remains constant.

Hierarchically structured titania films for application in hybrid solar cells are prepared by combining microsphere templating and sol-gel chemistry with an amphiphilic diblock copolymer as a structure-directing agent. The films have a functional structure on three size scales: (1) on the micrometer scale a holelike structure for reduction of light reflection, (2) on an intermediate scale macropores for surface roughening and improved infiltration of a hole transport material, and (3) on a nanometer scale a mesoporous structure for charge generation. Poly(dimethyl siloxane)-block-methyl methacrylate poly(ethylene oxide) (PDMS-b-MA(PEO)) is used as a structure-directing agent for the preparation of the mesopore structure, and poly(methyl methacrylate) (PMMA) microspheres act as a template for the micrometer-scale structure. The structure on all levels is modified by the method of polymer extraction as well as by the addition of PMMA particles to the sol-gel solution. Calcination results in structures with increased size and a higher degree of order than extraction with acetic acid. With addition of PMMA a microstructure is created and the size of the mesopores is reduced. Already moderate microstructuring results in a strong decrease in film reflectivity; a minimum reflectivity value of less than 0.1 is obtained by acetic acid treatment and subsequent calcination.

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The influence of nanoparticles on the domain orientation in a particle co-operated self-assembly process in thin diblock copolymer films is investigated toward the preparation of ordered magnetic nanoparticle arrays. Thin films are prepared from a mixture of chemically masked iron oxide nanoparticles and a polystyrene-block-poly (methyl methacrylate) diblock copolymer. The resulting nanostructures are investigated with grazing incidence small-angle X-ray scattering, atomic force microscopy and scanning electron microscopy. Nanoparticles arrange themselves spontaneously inside the upright cylindrical domains due to the selective affinity to the poly (methyl methacrylate) minority phase during the microphase separation process and due to the balance of the surface free energies between the polymers and the nanoparticle coating after annealing. The incorporation of the nanoparticles inside the cylindrical domains increases the diameter of the cylindrical domains and the distance between two neighboring domains. A spatially ordered arrangement of magnetic nanoparticles is observed below a critical concentration of 0.2 vol % for the investigated molecular weight of 77 kg/mol.