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Low molecular weight poly(ethylene glycol) silanes (PEG silanes) have been grafted onto the surface of silicon wafers in a one-step procedure yielding ultrathin and stable PEG monolayers. Structural investigation by means of X-ray reflectivity provided data on the thickness of the PEG monolayers. The layer thickness varied between 10 and 17 Å depending on the PEG silane concentration applied. These results have been confirmed by X-ray photoelectron spectroscopy measurements. Atomic force microscopy data indicate very smooth and homogeneous coverages with roughnesses of less than 3 Å. The PEG layers are hydrophilic as determined with advancing water contact angles between 36 and 39°.

effectively a disposable consumable, with properties which can be easily tuned in the production process.The TPSs we generated can be considered to be hybrid structures, referred to as a solid-inverse structure, consisting of a solid nanostructure and an identical shaped void (inverse structure) directly above it. In line with Babinet's principle, the roles of electric and magnetic fi elds are switched between solid and inverse structures. The implications of this are that symmetry equivalent electric and magnetic modes of the solid and inverse structures are spatially located directly above each other, and can consequently couple in an analogous manner to hybridization of orbitals in molecular systems. [ 23 ] We show with our chiral hybrid metafi lms, that by controlling the spatial overlap between the solid and inverse structure, using fi lm thickness, the coupling between electric and magnetic modes can be controlled enabling the chiral/optical properties to be manipulated with relative ease. This is a far more versatile approach to manipulating coupling in hybrid metamaterials than the current paradigm of altering the geometric design. [ 24 ] Our work demonstrates that fi lm thickness is an important parameter in the metamaterial design tool kit. To illustrate the potential of the tunable "disposable" TPS, we present an exemplar case where a chiral substrate, consisting of a periodic array of "shuriken" indentations which are either left (LH) or right handed (RH), is used for picogram characterization of protein structure with "plasmonic polarimetry." [ 5 ] The combination of the low cost injection-molded templates and the tunability of the fi lms they can be used to produce, make the present study a signifi cant step in the technological application of metamaterials.The shuriken TPSs were fabricated using a new approach for templating Au fi lms on nanostructured polycarbonate substrates. Injection molding enables high-throughput manufacturing of sub-micrometer resolution nanosurfaces with high levels of reproducibility and quality. [ 21,25 ] In this work, we fabricate injection-molded polycarbonate templates, Figure 1 A, that consists of chiral shuriken shaped indentations, of either left or right handedness, arranged in a square lattice. A detailed description of the injection-molding process can be found elsewhere. [ 16,19,22,26 ] The depth of the indentation is 80 nm while the distance from the end of one arm to that of the end of the arm opposite is 500 nm. The periodicity of the array is 700 nm. Due to the nature of injection molding, the edges of the structure are not perfectly sharp and the inner walls of the structures are sloped by approximately 30° (see Supporting Information).We deposited fi lms of Au with thickness ranging from 20 to 100 nm on to the nanostructured polycarbonate template to produce the TPS samples, Figure 1 B,C. The continuous nature of the Au fi lms is evidenced by an absence of charging in scanning electron microscope (SEM) images of the substrates (see Artifi cially engineere...

Conjugated polymers such as polypyrrole (PPy) are of interest as artificial muscles. Although one of the most important parameters for this application is the magnitude of the volume change, estimates of this have varied greatly. We wanted a simple method to measure volume change directly and in situ on thin films, so we chose atomic force microscopy (AFM). We present results on polypyrrole doped with dodecylbenzenesulfonate (DBS) patterned into small rectangles using photolithography. The volume change was strongly anisotropic, increasing by over 35 % in the reduced state compared to the oxidized state in the direction perpendicular to the plane of the substrate but by much less parallel to the substrate.The volume of polypyrrole can be controlled by an applied potential. [1±9] The volume change is thought to be governed primarily by the insertion and de-insertion of ions and solvent that occurs during oxidation and reduction (redox), with a reduction in volume when ions exit and an increase when they enter. [1,10±14] The electrochemical redox process, also called doping/undoping, can be represented by Equations 1 and 2. P + (A ± ) + C + + e ± . P o (AC)(1) P + (A ± ) + C + + e ± . P o + A ± + C +In these equations, P + represents the doped (oxidized) state of the polymer and P o the undoped (reduced, neutral) state. P + (A ± ) indicates that the anion A ± is incorporated in the polymer as a dopant. In the first case, the cations enter the polymer during reduction, while in the second case the anions leave during reduction in order to maintain charge neutrality. Both processes may occur simultaneously. Al-though not shown in these equations, the ions are often accompanied by their solvation shells. [2,11,15±17] Estimates of the magnitude of the volume change that can be achieved vary greatly. The strain was measured directly by Chiarelli et al. and Della Santa et al. [12,18,19] Using free-standing PPy films obtained commercially and doped with benzenesulfonate, the strain was measured during redox in the direction parallel to the film surface using a displacement transducer and servo-controlled actuator. Strains of 0.5±2 % were obtained. Another way of determining the volume change is with a bending bilayer. The degree of bending can be related to the strain by making a number of assumptions about the mechanical behavior if the elastic moduli and thicknesses of the layers are known. This is an indirect method and was used by Pei et al., [13,20] who calculated strains of 0.45±3.4 % in polypyrrole doped with various anions, again in the direction parallel to the film surface. For polyaniline films, the strain was estimated to be <1 %. [21] A completely different method was used by Otero et al., [3] who measured the mass and density of oxidized and reduced PPy films after they were removed from the electrochemical cell and dried. They found a difference in mass of 35 %, but no difference in density (1.5 g/cm 3 in both cases), and concluded that the volume change must therefore also be 35 %. Baughman et al. ...

The nanometer scale topography of self‐assembling structural protein complexes in animals is believed to induce favorable cell responses. An important example of such nanostructured biological complexes is fibrillar collagen that possesses a cross‐striation structure with a periodicity of 69 nm and a peak‐to‐valley distance of 4–6 nm. Bovine collagen type I was assembled into fibrillar structures in vitro and sedimented onto solid supports. Their structural motif was transferred into a nickel replica by physical vapor deposition of a small‐grained metal layer followed by galvanic plating. The resulting inverted nickel structure was found to faithfully present most of the micrometer and nanometer scale topography of the biological original. This nickel replica was used as a die for the injection molding of a range of different thermoplastic polymers. Total injection molding cycle times were in the range of 30–45 seconds. One of the polymer materials investigated, polyethylene, displayed poor replication of the biological nanotopographical motif. However, the majority of the polymers showed very high replication fidelity as witnessed by their ability to replicate the cross‐striation features of less than 5 nm height difference. The latter group of materials includes poly(propylene), poly(methyl methacrylate), poly(L‐lactic acid), polycaprolactone, and a copolymer of cyclic and linear olefins (COC). This work suggests that the current limiting factor for the injection molding of nanometer scale topography in thermoplastic polymers lies with the grain size of the initial metal coating of the mold rather than the polymers themselves. magnified image