Polymer-coated PtCo nanoparticles deposited on diblock copolymer templates: chemical selectivity versus topographical effects.

Metal-polymer hybrid films are prepared by deposition of polymer-coated PtCo nanoparticles onto block copolymer templates. For templating, a thin film of the lamella-forming diblock copolymer poly(styrene-b-methyl methacrylate) P(S-b-MMA) is chemically etched and a topographical surface relief with 3 nm height difference is created. Two types of polymer-grafted PtCo nanoparticles are compared to explore the impact of chemical selectivity versus the topographical effect of the nanotemplate. A preferable wetting of the polystyrene (PS) domains with poly(styrenesulfonate) (PSS)-coated PtCo nanoparticles (instead of residing in the space between the domains) is observed. Our investigation reveals that the interaction between PSS-coated nanoparticles and PS domains dominates over the topographical effects of the polymer surface. In contrast, a non-selective deposition of poly(N-vinyl-2-pyrrolidone) (PVP)-coated PtCo nanoparticles and the formation of large metal-particle aggregates on the film is observed.

In situ X-ray study of the structural evolution of gold nano-domains by spray deposition on thin conductive P3HT films.

Gold (Au) nanoparticles are deposited from aqueous solution onto one of the most used conductive polymers, namely poly(3-hexylthiophene) (P3HT), using airbrush deposition. We report on the structure formation and packing of the Au nanoparticles after a 5 s spray cycle. In situ grazing incidence small-angle X-ray scattering (GISAXS) measurements with 20 ms time resolution allow a real-time observation of the emergence and evolution of the microstructure during a spray cycle and subsequent solvent evaporation. The results reveal multistage nanoscale ordering of the Au nanoparticles during the spray cycle. Further ex situ atomic force microscopy measurements of the sprayed films showed the formation of Au monolayer islands on top of the polymer film. Our study suggests that the solvent-substrate interaction as well as solvent evaporation kinetics are important factors that need to be taken into consideration in order to grow a compact uniform monolayer film for the fabrication of ultrathin films using airbrush deposition.

Note: Comparison of grazing incidence small angle x-ray scattering of a titania sponge structure at the beamlines BW4 (DORIS III) and P03 (PETRA III).

Grazing incidence small angle x-ray scattering (GISAXS) is a powerful technique for morphology investigation of nanostructured thin films. GISAXS measurements at the newly installed P03 beamline at the storage ring PETRA III in Hamburg, Germany, are compared to the GISAXS data from the beamline BW4 at the storage ring DORIS III, which had been used extensively for GISAXS investigations in the past. As an example, a titania thin film sponge structure is investigated. Compared to BW4, at beamline P03 the resolution of larger structures is slightly improved and a higher incident flux leads to a factor of 750 in scattered intensity. Therefore, the acquisition time in GISAXS geometry is reduced significantly at beamline P03.

Note: grazing incidence small and wide angle x-ray scattering combined with imaging ellipsometry.

The combination of grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) with optical imaging ellipsometry is presented as an upgrade of the available measurement techniques at the wiggler beamline BW4 of the Hamburger Synchrotronstrahlungslabor. The instrument is introduced with the description of the alignment procedure to assure the measurement of imaging ellipsometry and GISAXS∕GIWAXS on the same sample spot. To demonstrate the possibilities of the new instrument examples of morphological investigation on films made of poly(3-hexylthiophene) and [6,6]-phenyl-C(61) butyric acid methyl ester as well as textured poly(9,9-dioctylfluorene-alt-benzo-thia-diazole) are shown.

Grazing incidence wide angle x-ray scattering at the wiggler beamline BW4 of HASYLAB.

We present an upgrade of the available measurement techniques at the wiggler beamline BW4 of the Hamburger Synchrotronstrahlungslabor (HASYLAB) to grazing incidence wide angle x-ray scattering (GIWAXS). GIWAXS refers to an x-ray diffraction method, which, based on the measurement geometry, is perfectly suited for the investigation of the material crystallinity of surfaces and thin films. It is shown that the overall experimental GIWAXS setup employing a movable CCD-detector provides the capability of reliable and reproducible diffraction measurements in grazing incidence geometry. Furthermore, the potential usage of an additional detector enables the simultaneous or successive measurement of GIWAXS and grazing incidence small angle x-ray scattering (GISAXS). The new capability is illustrated by the microbeam GIWAXS measurement of a thin film of the conjugated polymer poly(3-octylthiophene) (P3OT). The investigation reveals the semicrystalline nature of the P3OT film by a clear identification of the wide angle scattering reflexes up to the third order in the [100]-direction as well as the first order in the [010]-direction. The corresponding microbeam GISAXS measurement on the present morphology complements the characterization yielding the complete sample information from subnanometer up to micrometer length scales.

Layered TiO2: PVK nano-composite thin films for photovoltaic applications. TiO2: PVK nano-composite thin films.

The influence of the solvent used for spin-coating on the homogeneity of poly(N-vinylcarbazole) (PVK) films is investigated. Homogenous films are obtained only by the use of toluene, solution in tetrahydrofuran (THF) and chloroform results in radially oriented inhomogeneities and films prepared by use of N-methylpyrrolidone and dimethylacetamide show particle formation during spin-coating. Layered nano-composite thin films are prepared by spin-coating a PVK film on top of a nano-structured titanium dioxide ( TiO2) layer. The TiO2 thin films are prepared by a sol-gel process using an amphiphilic copolymer as structure-directing agent. Structural characterisation of the TiO2 :PVK nano-composite films is done by field emission scanning electron microscopy (FESEM) and grazing-incidence small-angle scattering (GISAXS). Bare TiO2 films are probed for comparison. Light is basically only absorbed in the ultraviolet regime and absorption slightly increases upon addition of PVK, which makes the layered TiO2 :PVK nano-composite thin films good candidates for UV photovoltaic devices. Furthermore, absorption remains stable over a period of several days.

In situ GISAXS investigation of gold sputtering onto a polymer template.

Microphase-separation structures in mixed diblock-triblock copolymer thin films are used for the incorporation of gold atoms inside the polymer matrix via sputtering of gold. Polystyrene (PS) spheres are arranged in a liquidlike type with a well defined nearest neighbor distance inside a polyisoprene matrix acting as a template for directing the gold atoms. Sputtering conditions are selected with a very low sputtering rate to avoid clustering in the atmosphere so that gold reaches the polymer surface in its atomic state. Due to the mobility of the gold atoms and the selective interaction with the PS parts of the microphase separation structure, gold is accumulated inside the polymer film in the PS spheres, as probed in situ with grazing incidence small-angle X-ray scattering (GISAXS). Nominally 4.3 A of gold is deposited, which by diffusion is spread out vertically over a thickness of 280 nm. UV-vis spectroscopy reveals a small blue shift for the gold sputtered polymer film. Atomic force microscopy proves the absence of gold clusters on the film surface. For low sputtering rate, GISAXS proves good sensitivity for gold migration inside the polymer film and opens new possibilities for studying polymer-metal interaction.