A detailed investigation of the processing parameters influencing the oxidative polymerization of 3,4‐ethylenedioxythiophene (EDOT) and a methanol‐substituted derivative (EDOT–CH2OH) was performed with the goal of maximizing the conductivity of the polymer. We show that the conductivity can be significantly enhanced by varying the monomer, oxidant (iron(III) p‐toluenesulfonate (Fe(OTs)3)), weak base (imidazole (Im)), solvent (various alcohols), and solution concentrations. The effect of each variable on the final materials properties is investigated, and the parameters have been optimized to achieve conductivities as high as 900 S cm–1. Surface resistance below 150 Ω/□ for 80–90 nm thick films with visible‐spectrum transparency exceeding 80 % is achieved. The combination of these properties makes the films highly suitable for numerous device applications.

Creation of an orientationally ordered hierarchical nanocomposite can be done by the preferential insertion of individual polymer-covered clay layers into block copolymer (BCP) microdomainsin the present instance, PS-functionalized silicate layers into the polystyrene (PS) domains of a styrene−butadiene−styrene triblock copolymer (SBS). We present here the method required to achieve such an ordered block copolymer−nanoparticle composite and report preliminary mechanical properties. PS is grafted-to or polymerized-from individual clay sheets in order to provide a neutral enthalpic interaction between the PS chains on the clay layers and the PS blocks in the SBS. The molecular weight of the PS chains tethered to the clay was varied, and we show that higher molecular weight is critical in obtaining individual clay sheets dispersed in the SBS matrix. When exfoliated, the clay sheets serve as a template for the lamellar domains. Because of their large areal dimensions and concentration, the clay particles likely form a discotic nematic that is responsible for the observed orientational flipping transition of the BCP layers during the roll-cast process. We also show through experiments and simulations that the mechanical properties of these anisotropic hierarchical nanocomposites are not significantly changed by the insertion of 2 wt % of the clay sheets for deformation parallel to the lamellae.

In vitro assembly of Wiseana iridescent virus (WIV) yields iridescent pellets and films with structural color more vivid than in the native insect. WIV is icosahedral in shape, 140 nm in diameter, with 30 nm long fibrils attached to the outer surface, and exhibits a surface charge ca. 1/6th that of a comparable polymer colloid. The low surface charge and tethered chains on the virus surface allow the facile modification of the interparticle distance. Directed sedimentation yields predominantly an amorphous liquid‐like packing of the virus. Such samples exhibit a broad reflection band that is angle independent and for which the broad maximum can be reversibly shifted from blue towards red with increased hydration. Slow sedimentation and flow‐assisted assembly methods produce thin films with a polycrystalline morphology that exhibit narrower, more intense reflectivity peaks, which are hydration and angle dependent. This study points toward the potential of viral particles for photonic crystals where their unique structural features (icosahedral symmetry, extreme monodispersity, precise surface functionalization, and tethered surface chains of low surface‐charge density) may lead to superior control of optical properties of their assembled arrays.

Submicron patterns of block copolymers were generated using an elastomeric mold against solutions of block copolymers. To prevent the swelling of the elastomeric mold by the solvent used in the block copolymer solution, a thin layer of amorphous fluorinated polymer was coated on the surface of the mold. The comparison of patterns generated using an unmodified mold with those generated using a modified mold is also reported. Coupled with their microphase separation at nanometer scale, these block copolymer patterns can be applied in nanofabrication as nanotemplates.

Many naturally occurring solids possess periodic structures that give rise to visible photonic crystal properties, [1] commonly termed structural colors. Some stunning examples are butterfly wings (one-dimensional, 1D), [2] abalone shells (1D), [3] sea-mouse spines (two-dimensional, 2D), [4] and natural opals (three-dimensional, 3D).[5] Exploitation of other periodic natural structures, is however limited by the inherently large size scale and the low dielectric contrast of the materials. Furthermore, these generally more complex geometries are a challenge to model correctly in order to obtain correct band diagrams. Here we report the development of a high fidelity cyclic size reduction and infiltration scheme, and apply it to a sea urchin exoskeleton to successfully fabricate a high dielectric contrast 3D photonic crystal exhibiting a stop band in the mid-IR range. The band structure of the exoskeleton is modeled using level set mathematics and agrees well with the experimental reflectivity exhibited by the 3D bicontinuous tellurium network of the replicated urchin.Periodic bicontinuous structures [6] are prevalent in systems such as surfactants, [7] block copolymers, [8] plant prolamellar bodies, [9] cell membranes, [10] and even in man-made playground architectures.[11] Naturally occurring bicontinuous structures are also found in the skeletons of sea urchins (termed stereom). [12,13] Stereoms are comprised of interpenetrating high magnesium calcite (incorporating up to 15 % MgCO 3 ) and soft tissue, with periodic spacings typically on the order of a few tens of micrometers. These labyrinthine composite structures are believed to have evolved to provide excellent nutrient access and to prevent crack propagation through the calcitic plates, although this latter notion has recently been challenged. [14] Some efforts to utilize these structures as templates for creating engineered material systems have previously been reported.[15±18] Among the various labyrinthine structures, the periodic structure termed ªrecti-linearº by marine biologists, [13] also commonly known as the ªPlumber's Nightmareº by the self-assembly community [19] and as ªSchwarz's P-surfaceº by mathematicians, [20] may exhibit unique optical characteristics. Rectilinear stereoms are found in many different sea urchin species, and we have used a stereom from the interambulacral plates of the Phyllacanthus species, having a unit cell with a lattice parameter of approximately 30 lm (see Fig. 1a).A perfectly periodic rectilinear stereom may be approximated using a level set equation for Schwarz's P-surface family [21] 10(cos x + cos y + cos z) ± 5.1(cos x cos y + cos y cos z + cos x cos z) = tThe structure has cubic Pm3 Å m symmetry; each node has six arms directed outwards along the three orthogonal directions. Varying the magnitude of t dilates or contracts the thickness of the arms defining the dividing surface and thus the network volume fraction of the bicontinuous structure. Calculations based on confocal microscopy and comparisons of scanning...