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The electrodes of a hybrid electrochemical capacitor which utilize the quinone (Q)-hydroquinone (QH2) couple, a prototypical organic redox system known to provide fast and reversible proton-coupled electron-transfer reactions, are deterministically mesostructured via a colloidal templating strategy to provide good ion and electron transport pathways, enabling a high rate performance. Specifically, a conducting polymer, polypyrrole (PPy), is functionalized with a pseudocapacitive material, a Q/QH2-containing catechol derivative, by noncovalent interactions. The mesostructure of this hybrid material is formed into an ordered 3D porous structure by a polystyrene colloidal crystal template-assisted electrosynthesis. The catechol derivative is sufficiently bound to the PPy through noncovalent interactions to provide a volumetric capacitance as high as ≈130 F cm−3 and a capacitance retention of ≈75% over 10 000 charging/discharging cycles. When compared with a randomly structured electrode, the deterministically structured electrode exhibits an improved rate performance due to the mesostructure facilitated electron and ion transport.

Protein adsorption and reversible cell attachment are investigated as a function of the grafting density of poly( N- isopropyl acrylamide) (PNIPAM) brushes. Prior studies demonstrated that the thermally driven collapse of grafted PNIPAM above the lower critical solution temperature of 32 ° C is not required for protein adsorption. Here, the dependence of reversible, proteinmediated cell adhesion on the polymer chain density, above and below the lower critical solution temperature, is reported. Above 32 ° C, protein adsorption on PNIPAM brushes grafted from a non-adsorbing, oligo(ethylene oxide)coated surface exhibits a maximum with respect to the grafting density. Few cells attach to either dilute or densely grafted PNIPAM chains, independent of whether the polymer brush collapses above 32 ° C. However, both cells and proteins adsorb reversibly at intermediate chain densities. This supports a model in which the proteins, which support reversible cell attachment, adsorb by penetrating the brushes at intermediate grafting densities, under poor solvent conditions. In this scenario, reversible protein adsorption to PNIPAM brushes is determined by the thermal modulation of relative protein-segment attraction and osmotic repulsion.

A self-healing approach for optically transparent thermoplastic polymers, based on plasticizer-induced solvent welding, is reported. For the specific system investigated, dibutylphthalate (DBP) filled urea-formaldehyde capsules are dispersed in a polymethylmethacrylate (PMMA) matrix. Upon a damage event, DBP is released into the crack, and locally plasticizes and swells the polymer, enabling it to remend. Two challenges are addressed to maintain optical transparency: minimization of light scatter from the capsules in the polymer matrix and minimization of light scatter from the healed polymer. PMMA films containing DBP capsules have good transmissive properties as a result of the close index match between PMMA and DBP. The transmission properties are better than, for example, when DBP capsules are dispersed into a poorly index matched matrix, such as polystyrene. In the DBP PMMA system, the healed material is inherently index matched to the polymer matrix and thus the polymer's original optical properties are largely restored. Self-healing using both small capsules, 1.5 μm in diameter, and large capsules, 75 μm in diameter is demonstrated. Smaller capsules are particularly important for thin polymer films which are not thick enough to hold the larger capsules. Polymer films with smaller capsules also have very good transmission properties due to a minimization of light scattering by the small size of the capsules. Large capsules enable healing of larger damage events, but do inherently result in some light scattering. This plasticizer-based approach to self-healing is shown to enable recovery of the protective properties and a portion of the mechanical properties of a polymeric film.

A 2D polystyrene colloidal crystal self-assembled on a flat gold surface supports multiple photonic and plasmonic propagating resonance modes. For both classes of modes, the quality factors can exceed 100, higher than the quality factor of surface plasmons (SP) at a polymer–gold interface. The spatial energy distribution of those resonance modes are carefully studied by measuring the optical response of the hybrid plasmonic–photonic crystal after coating with dielectric materials under different coating profiles. Computer simulations with results closely matching those of experiments provide a clear picture of the field distribution of each resonance mode. For the SP modes, there is strong confinement of electromagnetic energy near the metal surface, while for optical modes, the field is confined inside the spherical particles, far away from the metal. Coating of dielectric material on the crystal results in a large shift in optical features. A surface sensor based on the hybrid plasmonic–photonic crystal is proposed, and it is shown to have atomic layer sensitivity. An example of ethanol vapor sensing based on physisorption of ethanol onto the sensor surface is demonstrated.

The fabrication and characterization of two-photon polymerized features written within and outside of colloidal crystals is presented. Two-photon polymerization (TPP) response diagrams are introduced and developed to map the polymerization and damage thresholds for features written via modulated beam rastering. The use of tris[4-(7-benzothiazol-2-yl-9,9-diethylfluoren-2-yl)phenyl]amine (AF-350) as an initiator for TPP is demonstrated for the first time and TPP response diagrams illustrate the polymerization window. These diagrams also demonstrate that the polymerization behavior within and outside of colloidal crystals is similar and electron microscopy reveals nearly identical resolution. Fluorescence confocal microscopy further enables visualization of non-self-supporting, three-dimensional TPP features within self-assembled photonic crystals. Finally, microspot spectroscopy is collected from a two-photon feature written within a colloidal crystal and this is compared with simulation.

Aqueous gel-like lyotropic liquid crystals with extensive hydrogen bonding and nanoscale hydrophilic compartments have been used to define the growth of macroscopic nanotemplated CdS and CdTe thin films. These mesoporous semiconductor films contain a hexagonal array of 2.5 nm pores, 7 nm center-to-center, that extend in an aligned fashion perpendicular to the substrate. The CdS is deposited on a polypropylene substrate by a reaction between Cd(NO 3 ) 2 dissolved in the liquid crystal and H 2 S transported via diffusion through the substrate. The CdTe is electrodeposited on indium-tin-oxide-coated glass from TeO 2 and Cd(NO 3 ) 2 , both of which are dissolved in the liquid-crystal template. The porous nature of the CdTe films enables chemical transformations of the entire bulk of the film. As electrodeposited, the CdTe films are Te rich and, in contrast to a non-templated film, the excess Te could be removed via a chemical treatment, proving the continuity of the pores in the nanotemplated films. These results suggest that liquid-crystal lithography with hydrogen-bonding amphiphiles may be a useful approach to create materials with nanoscale features over macroscopic dimensions.

Electrically conducting nanocomposites of bismuth metal and insulating ceramic phases of SiO2 and MgO were generated via high-energy ball milling for 24 h using zirconia milling media. The resulting nanocomposites contain Bi nanoparticles with sizes down to 5 nm in diameter. The morphology is a strong function of the oxide phase: specifically, the Bi appears to wet MgO while it forms spherical nanoparticles on the SiO2. X-ray diffraction measurements indicate a nominal bismuth grain size of 50 nm, and peak fitting to a simple bidisperse model yields a mixture of approximately 57 % bulk bismuth and 43 % 27 nm diameter crystallites. Nanoparticles as small as 5 nm are observed in transmission electron microscopy (TEM), but may not constitute a significant volume fraction of the sample. Differential scanning calorimetry reveals dramatic broadening in the temperatures over which melting and freezing occur and a surprising persistence of nanostructure after thermal cycling above the melting point of the Bi phase.

FeF2 is considered a promising conversion compound for the positive electrode in lithium-ion batteries due to its high thermodynamic reduction potential (2.66 V vs Li/Li+) and high theoretical specific capacity (571 mA h g−1). However, the sluggish reaction kinetics and rapid capacity decay caused by side reactions during cycling limit its practical application. Here, the fabrication of Ni-supported 3D Al2O3-coated FeF2 electrodes is presented, and it is shown that these structured electrodes significantly overcome these limitations. The electrodes are prepared by iron electrodeposition on a Ni support, followed by a facile fluorination process and Al2O3 coating by atomic layer deposition. The 3D FeF2 electrode delivers an initial discharge capacity of 380 mA h g−1 at a current density of 200 mA g−1 at room temperature. The 3D scaffold improves the reaction kinetics and enables a high specific capacity by providing an efficient electron pathway to the insulating FeF2 and short Li diffusion lengths. The Al2O3 coating significantly improves the cycle life, probably by preventing side reactions through limiting direct electrode–electrolyte contact. The fabrication method presented here can also be applied for synthesis of other metal fluoride materials on different 3D conductive templates.