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Christoph Weder

Publications and source records attributed to Christoph Weder.

8 recordsLinked to original sources
PubMed2006

Single-molecule spectroscopy of uniaxially oriented terrylene in polyethylene.

Single terrylene molecules doped into linear low-density polyethylene can be oriented by tensile deformation of the matrix. In measurements on ensembles at ambient and on single terrylene molecules at cryogenic temperature, strong orientation along the stretching direction was observed by polarization-resolved confocal microscopy. At cryogenic temperatures narrow and spectrally stable zero-phonon lines were found. The low saturation intensity of 0.07 W cm(-2) is consistent with an uniaxial orientation of terrylene in the sample plane.

Journal Article↗
PubMed2005

Synthesis, processing and properties of conjugated polymer networks.

Despite the diverse research activities focused on the chemistry, materials science and physics of conjugated polymers, the feature of conjugated cross-links, which can provide electronic communication between chains, has received little attention. This situation may be a direct consequence of the challenge to introduce such links while retaining adequate processability. Focusing on recent studies of materials for which charge transport or electrical conductivity data are available, this feature article attempts to present an overview of the synthesis, processing and electronic properties of conjugated polymer networks. For the purpose of this discussion, two distinctly separate architectures-featuring covalent cross-links on the one hand and non-covalent organometallic bridges on the other-are treated in separate sections. The available data indicate that cross-linking can have significant benefits for intermolecular charge transfer if the polymers are carefully designed.

Journal Article↗
PubMed2005

Liquid crystalline nanowires in porous alumina: geometric confinement versus influence of pore walls.

Aligned liquid crystalline nanowires within ordered porous alumina templates show a pronounced texture on a macroscopic scale. We have investigated the influence of the geometric confinement and the nature of the pore walls on the mesophase formation by means of X-ray diffraction. The apparent texture is the result of a complex interplay of the pore geometry, interfacial phenomena, and the thermal history. Pores with a diameter of a few hundred nm guide the mesophase formation more efficiently than those with a diameter below 100 nm.

Aluminum Oxide↗
PubMed2004

Synthesis and optical properties of metallo-supramolecular polymers.

Metal-ligand interactions between metal ions, such as Zn2+, and ditopic low-molecular weight conjugated monomers, which utilize the 2,6-bis(1'-methylbenzimidazolyl)pyridine ligand, lead to the formation of supramolecular conjugated polymers with interesting optical properties.

Journal Article↗
PubMed2003

Dichroic ultraviolet light filters.

With the intention to produce dichroic filters for use in photoluminescent systems that rely on polarized UV light, we synthesized a number of linear, dichroic dyes, which absorb mainly in the near-UV range of the electromagnetic spectrum. These dyes were designed for compatibility with common thermoplastic polymers such as linear low-density poly(ethylene), poly(ethylene terephthalate), and polyamide-12. Films of these host polymers that consisted of 0.2% by weight of various dichroic UV dyes were produced by common melt-processing schemes. Uniaxial drawing of these films yielded highly dichroic UV filters with dichroic ratios in absorption that in some cases exceeded 100. The fact that these free-standing films display little or no coloration and are environmentally stable makes them useful for various applications that involve generation of polarized UV light.

Journal Article↗
PubMed2002

High charge carrier mobility in conjugated organometallic polymer networks.

The improvement of charge transport in conjugated polymers is a focal point of current research. It is shown here that the carrier mobility can be substantially increased through the introduction of conjugated cross-links between the conjugated chains. Novel organometallic polymer networks based on a poly(p-phenylene ethynylene) (PPE) derivative and Pt0 were synthesized by ligand-exchange reactions between the linear PPE and a low-molecular Pt complex. Time-of-flight measurements revealed ambipolar charge carrier mobilities of up to 1.6 x 10-2 cm2 V-1 s-1 for these materials, which are an order of magnitude higher than those of the neat polymer and represent the highest mobilities yet observed in disordered conjugated polymers.

Journal Article↗