Advanced Functional Materials

On page 3972, Pérez-Ramírez et al. introduce the hierarchy factor as a valuable descriptor to categorize hierarchical zeolites and to optimize their design for catalytic applications. They demonstrate a direct correlation between the catalytic performance of ZSM-5 in benzene alkylation and the hierarchy factor. Maximization of the hierarchy factor is achieved by enhancing the mesopore surface area without reducing the micropore volume. For this purpose, a novel desilication variant involving NaOH treatment in the presence of pore growth moderators (quaternary ammonium cations) is presented.

The inside cover image showns a side view of a hydroxyapatite membrane with aligned crystal domains synthesized as described by Liu et al. on page 3941. The microstructure of the membrane is engineered to promote proton transport through orientation of the proton conducting paths. These novel structures have significantly higher proton conductivity than traditional hydroxyapatite ceramics and may offer improved performance in intermediate temperature fuel cells.

Nanotechnology has had tremendous impact on drug delivery and diagnostics and has yielded a wide spectrum of novel carriers. Novel design parameters of polymeric carriers, such as shape and mechanical properties, are being explored, and the interplay of these parameters with the size and surface chemistry of particles is being investigated. Recent advances are highlighted, with particular focus on the importance of particle shape, and the challenges that are yet to be fulfilled are underscored.

Biocompatible zeolite anti-corrosion coatings have potential for success as bone scaffolding materials. In this work, reported by Y. Yan and co-workers, titanium-based dental implants are covered with zeolite MFI coatings to prevent against corrosion within the dental cavity. Zeolite coatings are non-toxic, and prevent the release of toxic ions from metals into tissue. The 3D micro-topology of the zeolites also enhances cell proliferation, differentiation, and surface adhesion.

The 3D microstructure of the zeolite MFI surface simulates the natural bone environment where osteoblast cells proliferate and differentiate faster than on metallic surfaces. Faster proliferation and differentiation on zeolite-coated versus bare titanium alloy indicate superior osteoconductive and osteoinductive properties of the zeolite surface. The interlayered bone tissue does not delaminate from the zeolite-coated titanium alloy's surface indicating that zeolite coatings may enhance the lifespan of orthopedic and dental implants

The self-assembly of pH-responsive Fab′-targeting polyion complex micelles consisting of a block copolymer, antisense oligonucleotides or siRNA, and dendrimers are reported. Upon complexation at neutral pH, the charge-compensated nucleic acid/ polymeric chains form a core–shell nanostructure. After cell uptake, the lower endosomal pH triggers physical dissociation of the micelle corona, thereby releasing a positively charged core with membrane-destabilizing properties.

A thin layer of a vertically aligned nanocomposite structure is deposited between the electrolyte, Ce_0.9Gd_0.1O_1.95 (CGO), and the thin film cathode layer, La_0.5Sr_0.5- CoO₃ (LSCO), of a thin-film solid-oxide fuel cell (TFSOFC). The maximum power density of the single cell with the interlayer varied with temperature from 329 to 812 mW cm⁻² at 550 and 700 °C, respectively (see figure), which demonstrates superior cell performance compared to the cells without the interlayer.

The energy levels of conjugated polymers, in particular the ionization energy (IE) and the electron affinity (EA), are shown to depend on the orientation of the polymer backbone with respect to organic/(in) organic interfaces. These findings provide new insights into the working principles of organic electronic devices and call for novel strategies in materials design.

The growth of chemical vapor deposition (CVD) diamond films is dependent on various deposition parameters, which are analyzed using high resolution EBSD. The primary fiber textures and their twinning components are shown, as well as various types of grain boundaries. A growth and a twinning model are proposed to explain the growth of CVD diamond films.

Inert hydrophobic upconversion nanoparticles (UCNPs) are converted into carboxyl/aldehyde-functionalized ones through a clean and flexible ozonolysis strategy (see figure). The carboxyl-functionalized UCNPs are characterized by good solubility in water, facilitating their application in biolabels, while aldehyde-modified UCNPs can easily be functionalized further for a myriad of other applications.

Gold nanoshell-based, targeted, multimodal contrast agents in the near-IR are fabricated and utilized as a diagnostic and therapeutic probe for magnetic resonance imaging, fluorescence optical imaging, and photothermal cancer therapy of breast carcinoma cells in vitro.

Nanotetrapods of pure CdS, core–shell (CdS)_1−x@(CdSe)_xand alloy CdS_1−xSe_x, displaying controlled photoluminescence properties (see image), are fabricated easily in water using ethylenediamine as a solvent-coordinating molecular template and characterized using diverse static and time-resolved spectroscopic methods. Photoluminescence shifts to the red continuously with the fractional concentration of Se in alloy nanotetrapods.

Here, M. T. Pettes and L. Shi report for the first time the thermal conductance, diameter, and chiral angle for a single single-walled carbon nanotube (SWCNT). A scanning electron micrograph of the suspended micro-thermometer device and transmission electron microscopy images used to determine the SWCNT's (22, 12) chirality are shown in this frontispiece image, along with the rendered unit cell.

Individual single-, double-, and multi-walled carbon nanotubes (CNTs) suspended between two microthermometers are characterized by thermal transport measurements and transmission electron microscopy. For the first time, the thermal conductance, diameter, and chiral angle are measured on the same individual single-walled CNT.

Orthorhombic boron carbide is grown by pyrolysis of diborane and methane. The figure elucidates the various morphologies of the nanostructures present in the spherical deposits found on the substrate after deposition. These morphologies include mostly smaller nanowires, some larger nanowires, and a few nanobelts. Depending on the temperature gradient, the size of the nanowires can be tuned.

Degraded organic solar cells can be recovered by thermal annealing treatment. Thermally stimulated current measurement reveals that the cause of photo-degradation is carrier accumulation. When the degraded organic solar cell is annealed, the accumulated carriers escape from the trap sites, and oppositely charged carriers then recombine in the photoactive layer.

A novel multistep surface crystallization technique is reported to synthesize ultrathin proton conducting ceramic membranes that are microstructurally engineered to enhance proton transport. Growth conditions are selected to align proton conducting pathways and eliminate resistive grain boundaries.

A new amorphous molecular material having a hole drift mobility of 1.0 ×  10⁻² cm² V⁻¹ s⁻¹, tris[4-(5-phenylthiophen-2-yl)phenyl]amine (TPTPA), is developed. pn-Heterojunction organic photovoltaic devices using TPTPA as an electron donor exhibit high performance with fill factors of 0.66∼0.71 and power conversion efficiencies of 1.7∼2.2% under air-mass 1.5 G illumination at an intensity of 100 mW cm⁻².

Multiple photochromic oxazines can be appended to a single macromolecular backbone on the basis of ring-opening polymerization reactions. The resulting photoresponsive materials switch from colorless to colored states upon UV irradiation and return thermally to the original form on a microsecond timescale. Furthermore, they tolerate hundreds of switching cycles with no sign of degradation.

A novel route to fabricate liquid crystalline polymers containing individually dispersed multiwalled carbon nanotubes (MWCNTs) based on the introduction of chemical moieties on the surface of the nanotubes is reported. The mechanical and thermal properties of MWCNT-filled polymer are strongly dependent on the type of MWCNT functionalization, state of dispersion, and interaction of the MWCNTs with the polymeric matrix.

A direct correlation between the catalytic activity in benzene alkylation and the hierarchy factor of ZSM-5 is demonstrated. The hierarchy factor introduced in this work enables the categorization of hierarchical zeolites and the optimization of their design for catalytic applications. High-hierarchy factor zeolites are engineered by alkaline treatment in the presence of quaternary ammonium cations that function as pore-growth moderators (right photograph).

The utilization of iron-based compounds encapsulated into carbon nanotubes as reactants in an electrochemical synthesis is reported for the first time. Prussian blue is electrosynthesized in a heterogeneous reaction between ferricyanide ions in aqueous solution, resulting in novel carbon nanotubes/Prussian blue electrodes. These are employed as a H₂O₂ sensor presenting low limit of detection and high sensitivity.

A novel molecular design of fluorene-based oligomers imparts these materials with excellent thermal stability, high fluorescence quantum efficiency, pronounced spectra stability, good hole injection, and excellent transporting ability. Deep-blue-light OLEDs based on these undoped fluorene-based emitters (see figure) achieved good performance with maximum efficiencies up to 1.91 cd A⁻¹ (external quantum efficiency of 2.7%). DFSTPA as a hole-injection and transporting material greatly improves device performance as compared to the common NPB-based device.