Solution behaviors of poly(styrene-co-sodium methacrylate) were studied by fluorescence spectroscopic methods using pyrene as a probe. The mol% of methacrylate was in the range 3.6–9.4. Water and N,N-dimethylforamide(DMF) mixture was used as a solvent (DMF/water = 0.2 mol %). The critical micelle (or aggregation) concentrations of ionomers and the partition coefficients of pyrene were obtained the temperature range 10–80°C. At room temperature, the values of CMCs (or CACs) were in the range 4.7 ×10-6 5.3 ×10-6 g/mL and we could not find any notable effect of the content of ionic repeat units within the experimental errors. Unlike CMCs, as the ion content increased, partitioning of pyrene between the hydrophobic aggregates and an aqueous media decreased from 1.5 ×105 to 9.4 ×104. As the temperature increased from 10 to 80 °C, the values of CMCs increased less than one order of magnitude. While, the partition coefficients of pyrene decreased one order of magnitude and the effect of the ion content became negligible.

The transformations induced by the application of a continuous bias voltage parallel to the growing surface during the sulfur-assisted hot-filament chemical vapor deposition (HFCVD) of nanocrystalline diamond (n-D) films were investigated by Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The films were deposited on molybdenum substrates using CH4, H2 and H2S. Bias voltages in the range of 0 – 800 VDC were applied parallel to the substrate surface continuously during deposition. The study revealed a significant improvement in the films' density and a lowering in the defect density of the nanocrystalline diamond structure for parallel bias (PB) voltages above 400V. These high PB conditions cause the preferential removal of electrons from the gaseous environment, thus leading to the net accumulation of positive species in the volume above the growing film, which enhances the secondary nucleation. The nanoscale carbon nuclei self-assemble into carbon nano-clusters with diameters in the range of tens of nanometers, which contain diamond (sp3-bonded C) in their cores and graphitic (sp2-bonded C) enclosures. Hence, the observed improvement in film density and in atomic arrangement appears to be connected to the enhanced presence of positively charged ionic species, consistent with models which propose that positively charged carbon species are the crucial precursors for CVD diamond film growth.

We investigate the surface kinetics of Pt using the extended embedded-atom method, an extension of the embedded-atom method with additional degrees of freedom to include the nonbulk data from lower-coordinated systems as well as the bulk properties. The surface energies of the clean Pt (111) and Pt (100) surfaces are found to be 0.13 eV and 0.147 eV respectively, in excellent agreement with experiment. The Pt on Pt (111) adatom diffusion barrier is found to be 0.38 eV and predicted to be strongly strain-dependent, indicating that, in the compressive domain, adatoms are unstable and the diffusion barrier is lower; the nucleation occurs in the tensile domain. In addition, the dissociation barrier from the dimer configuration is found to be 0.82 eV. Therefore, we expect that atoms, once coalesced, are unlikely to dissociate into single adatoms. This essentially tells that by changing the applied strain, we can control the patterning of nanostructures on the metal surface.

The interface-dependence of heteroepitaxial growth of iron oxide films is investigated by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). We show that the different chemical affinity to the metal substrate (Ru vs. Pt) and the step density (basal vs. vicinal Pt) significantly influence nucleation, heteroepitaxial crystal growth, and adhesion. Repeated Fe deposition-oxidation cycles lead to a Stranski-Krastanov growth mode on all substrates. On Ru(0001), metastable FeO(111) layers with strongly expanded lattice constants with a thickness up to 4 monolayers (ML) can be obtained by one-minute oxidation of the corresponding amount of Fe. Homogeneous nucleation of self-assembled, periodic Fe304(111) nanodomains embedded in an ultrathin FeO(111) film occurs on Ru(0001) in ∼4 ML thick FeO(111) films. Nucleation of Fe304(111) islands below 4 ML on Ru(0001) occurs preferentially at substrate step edges while on Pt(111), no influence of surface defects was observed. On a vicinal Pt substrate, the terrace width and step height triplicates under influence of the wetting FeO(111) film. Differences in the growth behavior are discussed in terms of the involved surface and interface free energies.

Submicron KMnF3 cubic and spherical nanoparticles were synthesized using the reverse micelle method. The nanostructures of the nanocrystals were studied by field emission electron microscopy and transmission electron microscopy. KMnF3 nanocrystals synthesized at room temperature started with cubic submicron particles (∼100 nm) and consisted of KMnF3 nanocrystallites (10-15 nm). As the reaction continued, the nanocrystals fused together and transformed into perfect cubic nanocrystals. Spherical beads composed of KMnF3 nanocrystallites were observed at low temperature synthesis. As the reaction continued, the spherical particles grew larger, however, no characteristic cubic shape of KMnF3 nanoparticles were observed. Even as they grew larger, there was no evidence of homogeneous crystal morphology as seen in the room temperature samples. Cubic shape KMnF3 nanocrystals were self-assembled into large area self-assembling patterns.

The electrostatic self-assembly of hetero-nanostructured multilayers of metal and semiconductor nanoparticles in polyelectrolytes, the self-assembly dynamics, and electrochemistry at the assembled films is reported. Polyacrylate-capped Pt (<d>=2.5 ± 0.6 nm) and Q-CdS nanoparticles (<d>=3.6 ± 0.5 nm) were assembled in poly(diallyldimethylammonium chloride). The nanoparticle assembly dynamics is shown to be a function of the nanoparticle solution ionic strength and its composition. Electrochemical studies at Pt nanoparticles in PDDA reveal that charge hopping is feasible through the nanocomposite film, and that the catalytic activity of the nanoparticles is retained in the assembled structures.

This study details development of hybrid mesoporous materials in which molecular transport through mesopores can be precisely controlled and reversibly modulated. Mesoporous silica materials formed by surfactant templating were modified by surface initiated atom transfer radical polymerization of poly(N-isopropyl acrylamide) (PNIPAAm) a stimuli responsive polymer (SRP) within the porous network. Thermo gravimetric analysis and FTIR spectroscopy were used to confirm the presence of PNIPAAm on the silica surface. Nitrogen porosimetry, transmission electron microscopy and X-ray diffraction analyses confirmed that polymerization occurred uniformly within the porous network. Uptake and release of fluorescent dyes from the particles was monitored by spectrofluorimetry and scanning laser confocal microscopy. Results suggest that the presence of PNIPAAm, a SRP, in the porous network can be used to modulate the transport of aqueous solutes. At low temperature, (e.g., room temperature) the PNIPAAm is hydrated and extended and inhibits transport of analytes; at higher temperatures (e.g., 50°C) it is hydrophobic and is collapsed within the pore network, thus allowing solute diffusion into or out of the mesoporous silica. The transition form hydrophilic to hydrophobic state on polymer grafted mesoporous membranes was determined by contact angle measurements. This work has implications for the development of materials for the selective control of transport of molecular solutes in a variety of applications.

Palladium nanowires have been electrodeposited into mesoporous silica thin film templates. Palladium continually grows and fills silica mesopores starting from a bottom conductive substrate, providing a ready and efficient route to fabricate a macroscopic palladium nanowire thin films for potentially use in fuel cells, electrodes, sensors, and other applications. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate it is possible to create different nanowire morphology such as bundles and swirling mesostructure based on the template pore structure.

Conjugated poly(2,5-thienylene ethynylene) (PTE)/silica nanocomposites with cubic and lamellar mesostructures have been synthesized. Surfactant directed assembly coorganized 2,5-diiodothiophene monomer and palladium-based catalyst within a silica matrix. Subsequent polymerization initiated by exposing the monomer/catalyst/silica nanostructures to acetylene gas resulted in the formation of an ordered, mesostructured poly(2,5-thienylene ethynylene)/silica nanocomposite as determined by XRD, UV-vis, FTIR, and TEM experiments. Mesostructured PTE with 287m2/g surface area is obtained after silica removal. Further polymerization of PTE oligomers occurs after exposure to acetylene gas due to active Pd catalyst attached to the polymer chains. This novel approach provides a unique route to synthesize mesostructured conjugated polymer/inorganic nanocomposites and porous mesostructured PTE.

Mesoporous silica materials have been studied for the time-dependent delivery of bioactive agents. It has already been shown that ibuprofen molecules can be encapsulated with loading as high as 30 wt% in MCM-41 silica, functionalized or not by amino groups. Interactions between the guest molecules and the host matrix have been investigated by 1H, 29Si and 13C solid state NMR spectroscopy. These experiments demonstrate an extremely high mobility of the ibuprofen molecules when the matrix is not functionalized, despite of the presence of a carboxylic function on the ibuprofen molecules. On the contrary, when the silica matrix is functionalized by amino groups, the 13C NMR response shows a strong restriction in mobility suggesting the existence of interactions between the amino groups and the carboxylic groups.

Mesoporous templated MCM-48 silica was prepared using a C16 surfactant as template. The MCM-48 powders and thin films were characterized by different techniques. Two types of porous supports were used, namely macroporous á-alumina and silicon microsieves. The supported MCM-48 layers were applied as liquid permeable membranes in pressure-driven nanofiltration and electric field-mediated ion transport experiments.

The physical and electronic properties of tungsten oxide and some related hybrid materials have been examined via various spectroscopic techniques and the results complemented by ab initio computation. Hybrid materials based on intercalated straight-chain σ,ω-diaminoalkanes in between sheets of corner-shared tungsten-oxide octahedra exhibit from XRD a linear expansion in the interlayer spacing with increasing number of carbon atoms in the amines. UV-visible diffuse reflectance spectra of several hybrid powders indicate a dominant absorption edge centred at 4.0 eV, with no apparent trend among the different samples as the alkyl chain length changes. This is higher than that of tungsten trioxide powder, which has an absorption edge centred at 2.8 eV. Ab initio calculations show that these experimental values may relate to the indirect band-gap energies of the respective compounds rather than the optical band gap. This was confirmed from the absorption coefficient results of WO3 thin films which yield a strong edge at 4.0 eV. Similar measurements of hybrid films with 1,12-diaminododecane as the organic spacer showed absorption throughout the visible range, with weak features at 4.2 and 4.9 eV.

We have previously shown that hierarchical self-organization is achieved upon physically bonding amphiphilic molecules to diblock copolymers. Here we discuss the effect of imposed shear flow to achieve overall alignment of the locally self-organized structures. We will first present shear aligned polystyrene-block-poly(4-vinyl pyridine) diblock copolymers (PS-b-P4VP), where pentadecyl phenol (PDP) has been hydrogen bonded to the pyridines. Depending on the selected molecular weights, eg. hexagonal arrangement of PS cylinders in the lamellar matrix of P4VP(PDP) can be obtained with high overall order of both structures. This is a template to obtain discrete PS nanorods, which have P4VP corona once the PDP molecules have been cleaved off by a solvent treatment. Selecting a relatively high molecular weight PS block and a short P4VP block leads to mesoporous materials with emptied cylinders with P4VP brushes at the walls. The glassy state of the PS matrix prevents the pores from collapsing. The pyridine groups of PS-b-P4VP can be protonated using eg. toluene sulphonic acid and the resulting polymeric salt has been complexed using PDP. The weight fractions have been selected so that the polyelectrolyte/amphiphile complex self-organizes into cylindrical domains with hexagonal packing. Shear alignment leads to high overall order. SAXS in combination with structural models suggests that within the cylinders there are parallel self-organized layers. The conductivity is anisotropic. We will also discuss dielectric reflectors based on self-organized block polyelectrolytes consisting PS-b-P4VP where DBSA has been complexed to P4VP. In this case, plasticization due to the oligomeric side chains promotes a facile structure formation at long periodicities in comparison to concepts based on eg. blends of high molecular weight polymers and block copolymers. Finally, plasticized comb-shaped supramolecules based on rigid conjugated poly(p-pyridine) are discussed. Even gentle shearing leads to highly aligned lamellar structures, which show efficient polarized photoluminescence.

The first synthesis of phenol-furfural polymer nanotubes of 2–3nm hollow diameter is demonstrated as well as those with a hexagonal mesostructure. These nanopolymers were obtained by the templating method using a two-step reaction. At the first step, phenol and furfural were moderately reacted into cooligomers in the presence of NaOH. The resulting cooligomeric species were fully anionized and then reacted with additional phenol and alkyl trimetyl ammonium bromide at 40-80°C. The major phase for the 80°C product obtained at low concentration of surfactant was identified as nanotubular polymers of 1.9-3 nm inside and 6 nm outside diameters depending on the chain length of surfactant. In contrast, hexagonal mesostructured polymers characterized by a definite XRD peak occurred preferentially in the reaction using high surfactant-concentrations.

Systematic studies of the growth temperature and growth rate effect of the formation of InAs/GaAs quantum dots (QDs) have been demonstrated. These QDs are formed with large InAs coverage (3.0 MLs) and periodic growth interruption via Strnski-Krastonov (S-K) epitaxial growth mode by using metalorganic chemical vapor deposition (MOCVD). The room temperature photoluminescence (PL) spectra show red-shift of peak wavelength by decreasing the InAs growth temperature from 540°C to 500°C. As growth rate increases from 0.05 ML/s to 0.2 ML/s at growth temperature of 500°C, PL linewidth could be narrowed and emission intensity could be increased. These results could be correlated to the In clusters and uniformity of InAs/GaAs QDs observed by scanning electron microscopy (SEM) image. Finally, the room temperature photoluminescence spectra of InAs/GaAs QDs directly capped with GaAs shows peak wavelength of 1.35 μm with narrow linewidth of 30.8 meV is obtained.

Polystyrene-block-poly(4-vinylpyridine) (PS-block-P4VP) diblock copolymer was complexed with dodecylbenzenesulfonic acid (DBSA), leading to comb-coil polymeric supramolecules PS-block-P4VP(DBSA)y (y = 1.0, 1.5, and 2.0). Complexes formed hierarchical lamellar structure with long period of ca. 1400 Å. Due to periodicity and refractive index contrast between the layers, transmission and reflectance measurements showed a relatively narrow incomplete bandgap at ca. 460 nm. The angular dependence of the bandgap was also studied using different angles (ø) relative to the surface normal. The mid-gap was blue-shifted when the incident angle was increased indicating that the lamellar structure was partly oriented by the surfaces of quartz glasses.

Zinc oxide (ZnO) nanorods have been grown by hydrolyzing Zn(OAc)2•2H2O in methanol solution. Nanoparticles in sizes ranging from 2 to 4 nm were first obtained at low concentration. The growth kinetics was monitored by UV-vis absorption spectroscopy. The precursor was then concentrated by 10 folds and refluxed at 60°C for 24 hours to form ZnO nanorods with an aspect ratio of 12. Ligand adsorption growth model was proposed to explain the anisotropic growth.

Growth of nanostructures with controlled shape, on inhomogeneously strained surfaces, is investigated by means of kinetic Monte Carlo (KMC) simulations. We propose a method to assemble self organized sub-lithographic nanostructures. The method is based on a strain-assisted mechanism for adatom surface diffusion and nucleation. For an inhomogeneous surface strain field there is normally a driving force toward the most tensile strained areas. It is shown by means of KMC simulations, that almost straight and continuous Ag nanowires can be produced on the Pt(111) surface if the growth is followed by high-temperature annealing. We suggest also how the method can be utilized as the first step of a process to reduce the circuit line width.

The properties of organic electronic materials in the solid-state are determined not only by those of individual molecules but also by those of ensembles of molecules. The ability to control the architectures of these ensembles is thus essential for optimising the properties of conjugated materials for use in electronic devices (light emitting diodes, field effect transistors, solar cells,…) and is primordial for potential technological applications in nanoelectronics.

Here, we report on the observation by atomic force microscopy (AFM) of 1D and 2D nanoscale architectures obtained in the solid-state from solutions of molecularly-dissolved conjugated block copolymers or oligomers, and demonstrate that the conjugated molecules can organize onto a surface over lengthscales from nanometers to several microns, forming semiconducting fibrils by π-stacking processes.

Europium-doped hexagonal-mesostructured and nanotubular yttrium oxides templated by dodecylsulfate species as well as surfactant free bulk oxides were synthesized by the homogeneous precipitation method. All the as grown nanostructured or bulk materials with amorphous or poorly crystalline frameworks showed weak luminescence bands at room temperature. On calcination at 1000°C these materials were converted into highly crystalline yttrium oxides, resulting in a total increase in intensity of all the bands by one order of magnitude. In the hexagonal-mesostructured system, the main band due to the 5D0-7F2 transition for the calcined phases showed a sharp but asymmetrical multiplet splitting indicating multiple Eu sites. Concentration quenching was found at a Eu content of 3 mol% or above for these phases. In contrast, the main emission for the calcined solids in the nanotubular system occurred as poorly resolved broad band and the intensity of the main band at higher Eu content was significantly enhanced compared with those for the other two systems.