Materials Literature
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Abstract Microparticles with controlled porosity have been widely used in various applications. In this Full Paper, a new method of freezing emulsions has been developed to prepare porous microparticles with unique aligned porosity. Aligned porous poly(ϵ‐caprolactone) microparticles are formed on an aligned porous pol…
The free four-coordinate Fe(III) porphyrin cation has not been previously observed due to its extreme electrophilicity. In order to isolate this very reactive species, we have synthesized a highly sterically hindered bis-pocket siloxyl porphyrin which has a top opening of only 2 Å. NMR studies of this Fe(III) porphyri…
First, molecular scale insight into the mobility of a novel class of organic materials for photonic applications with electro-optical activities larger than 300 pm/V is presented. A representative second order nonlinear optical (NLO) material of this class of self-assembling molecular glasses involving quadrupolar phe…
By combining both isothermal and rate heating experiments, structural relaxation times were determined in the glass transition range with in situ, high-temperature Raman spectroscopy. The obtained relaxation times agree well with the shear relaxation times obtained from viscosity data. Thus, the time scale for viscous…
We have measured how irradiation by Ar + and N + ions modifies electronic conduction in single-wall carbon nanotube (SWNT) networks, finding dramatically different effects for different thicknesses. For very thin transparent networks, ion irradiation increases localization of charge carriers and reduces the variable-r…
One-dimensional Au nanoparticles connected by ionic linkers self-assemble into a micrometer-scale network. Reactions between linker ions reinforce the assembly and lead to the formation of a continuous network. This continuous network demonstrates room-temperature Coulomb-blockade characteristics that are indicative o…
Numerous crystalline materials, including those of bioorganic origin, comprise incommensurate sublattices whose mutual arrangement is described in a superspace framework exceeding three dimensions. We report direct observation by neutron diffraction of superspace symmetry breaking in a solid-solid phase transition of…
Phase change random access memory (PRAM) is unique among semiconductor devices because heat is intrinsic to the operation of the device, not just a by-product. Here, we apply a material that is exotic in the context of typical semiconductor devices but has highly desirable properties for PRAM. Thin films of C60 are se…
A hierarchical nanostructure of PS-b-PEO is demonstrated (see figure) with a novel approach by solvent vapor annealing of a micropatterned block copolymer thin film selectively spun cast on microcontact printed surface of SAMs. Dewetting of the thin film, inevitable during the ordering of block copolymer microdomains…
Low coverage water adsorption on alkaline-earth oxides is studied by first principles methods and ab initio molecular dynamic simulations. On CaO and BaO(001), water dissociation is thermodynamically favored in contrast with the molecular adsorption found for MgO(001). On CaO(001), the barrier for water splitting is v…
We study the pyridinelike nitrogen-doped graphene (PNG) with dispersed transition metal (TM) atoms as a potential hydrogen storage medium using the pseudopotential density functional method. It is found that highly localized states near the Fermi level, which are derived from the nitrogen defects, contribute to strong…
Sub-micrometer-sized hollow tantalum oxide (Ta2O5) spheres with tunable shell thickness and void size have been fabricated exploiting beta-diketone-functionalized polystyrene (PS) beads as sacrificial templates in a sol-gel process. First, a controlled precipitation of Ta2O5 nanoparticles was carried out on the templa…
The confined crystallization of poly(ethylene oxide) (PEO) in predominantly spherical microdomains formed by several diblock copolymers was studied and compared. Two polybutadiene- b -poly(ethylene oxide) diblock copolymers were prepared by sequential anionic polymerization (with approximately 90 and 80 wt % polybutad…
Silks spun from the major (Ma) and minor (Mi) ampullate glands by the spider Nephila clavipes respond to water differently. Specifically, Ma silk supercontracts (shrinks 40-50% in length) while Mi silk does not contract at all when hydrated with water. In the present study, 1H --> 13C cross polarization magic angle sp…
Lanthanide complexes of the form Ln(hfa)3bpm (where Ln=Nd(III), Gd(III), or Tb(III); hfa=1,1,1,5,5,5-hexafluoroacetylacetone and bpm=2,2'-bipyrimidine) have been structurally characterized. The Nd and Gd complexes form one-dimensional arrays when X-ray-quality crystals are grown by the slow evaporation of concentrated…
Abstract We have successfully controlled the shape of gold nanocrystals through a simple and low‐cost hydrothermal method based on a modified polyol process. Well‐defined gold nanocrystals of icosahedral shape were synthesized in high yields by the rapid reduction of gold precursors with ethylene glycol (EG) in the pr…
A novel method for the fabrication of monodisperse mesoporous silica particles is suggested. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil ph…
The efficient photo-triggered surface relief formation in the H-boned supramolecular liquid crystalline system was performed for the first time. This supramolecular framework leads to facile and successful detachment of azobenzene unit from the SRG inscribed film with exact retention of the morphological periodicity.
Abstract Novel multifunctional magnetic gold nanocomposites (MGNCs) were synthesized for synchronous cancer therapy and diagnosis via magnetic resonance imaging (MRI). The MGNCs consist of magnetic kernels (aggregates of ultra‐sensitive MnFe2O4 magnetic nanocrystals wrapped in polymer) as effective MR contrast agents…
Landau-Ginsburg-Devonshire theory is introduced to investigate the size-dependent ferroelectric properties of BaTiO3 nanowires, with the consideration of polarization orienting along the radial direction. It is shown that the Curie temperature, mean polarization, and area enclosed by hysteresis loop decrease with the…