Conductive nanothick gold on hydrophilic polymeric nanomembranes

The properties of separation membranes have been predicted and proven to be outstanding when their thickness approaches the dimensions of the molecules being separated. Ultrafast diffusion and high selectivity of such nanomembranes promise significant economic benefits by fewer and shorter processes with lower pressures. However, their widespread and industrial application is commonly impaired by poor biocompatibility and laborious, costly fabrication of currently used materials. Here we present the fabrication of self-supporting, hydrophilic, permeable nanomembranes from a thermosetting resin. A facile spin-coating procedure is employed which can be altered to yield two different kinds of porosity: (i) diffusion channels intrinsic to the covalently crosslinked resin network allowing small molecule permeation and (ii) perforations of defined geometric shape and size suitable for biomacromolecule separations. We show that the permeability of type (i) can be tuned by adjusting the resin component concentrations whereas perforations in type (ii) are introduced by a phase separation approach. Their remarkable features make nanomembranes, in particular biocompatible ones, very attractive materials for fast (bio-)sensing or functional bio-composite materials. In this respect, we furthermore show that small molecule separation nanomembranes can be rendered electrically conductive by coating with a thin gold layer whilst permeability is preserved. Please click Additional Files below to see the full abstract

Crystallographic structure of ultrathin Fe films on Cu(100)

We report bcc-like crystal structures in 2-4 ML Fe films grown on fcc Cu(100) using scanning tunneling microscopy. The local bcc structure provides a straightforward explanation for their frequently reported outstanding magnetic properties, i.e., ferromagnetic ordering in all layers with a Curie temperature above 300 K. The non-pseudomorphic structure, which becomes pseudomorphic above 4 ML film thickness is unexpected in terms of conventional rules of thin film growth and stresses the importance of finite thickness effects in ferromagnetic ultrathin films.Comment: 4 pages, 3 figures, RevTeX/LaTeX2.0