A new method for the formation of “smart” near-surface nanoscale composites has been developed. In this approach, small precipitates of active phases are embedded in the near-surface region of the material that is to be modified by a combination of ion implantation and thermal processing. The dispersion, concentration, and microstructure of the nanocrystals formed in the substrate material can be tailored through a careful choice of processing parameters – making this approach well suited to high-value-added, high-technology applications. The applicability of this approach to forming “smart” surfaces on otherwise inactive materials was established in the case of VO2 precipitates which were embedded in A12O3 single crystals to create a medium suitable for optical applications – including optical data storage. Most recently, this concept has been extended to the fabrication of magnetic-field-sensitive nanostructured surfaces by forming magnetostrictive precipitates of materials such as Ni or RFe2 (with R = Tm, Tb, Sm) that are embedded in various single-crystal-oxide hosts. These nanostructured, active surface composites have been characterized using XRD, RBS, TEM, and magneto-optical techniques.

The template method has been used to prepare concentric-tubular composite microstructures. These composite structures consist of an outer tubule composed of one material encapsulating concentric inner tubules composed of other materials. Tubular composites of this type consisting of metals, semiconductors, polymers, and Li-ion intercalation materials have been prepared. The chemical strategies used to prepared these composite structures include electroless plating of Au, electropolymerization of electronically conductive and insulating polymers, electrodeposition of metals and semiconductors, and sol-gel synthesis.

Nanoscale TiB2/TiN films have been prepared by d.c. and r.f. magnetron non-reactive sputtering and examined by TEM, SAED, SEM, AES, XPS, XRD, AFM as well as nanoindentation. Attention has been focused on both bulk and surface physical-mechanical properties. The effect of the latter on the nanoindentaion test results seems to be very important. Two types of film fracture under a Vickers indentor connected with homogeneous and inhomogeneous deformation have been described.

New composites based on nano-size particles provide a promising route to the fabrication of novel materials for advanced technology applications. To produce desired materials, it is important to control the composition and distribution of nanoclusters within the bulk or surface coating of nanostructured materials. Towards this purpose, we have developed a novel method of processing nanocomposite materials utilizing colloidal chemistry techniques to tailor their microstructure. Unique composite aggregates of nanoparticles with a core-shell structure were prepared using a special scheme of controlled polymer adsorption. Polymers which specifically adsorb on both nano- and micron- size particles are used as tethers to enable desired coating of the later particles with the former and to enhance the cluster integrity. Nanocomposite particles consisting of micron-size alumina or silicon nitride as cores and nano-size alumina, titania, or iron oxide as shell particles have been successfully prepared using this process. The surface charge of the core particles is reversed after the adsorption of polyacrylic acid polymers. This promotes the interaction between the core and the shell particles and therefore nanoparticles added subsequently to the core particle suspension coat on core particles by electrostatic as well as possibly hydrogen bonding bridging mechanisms. Success of the process depends to a large extent on the absence of homoflocculation of nanoparticles and this is achieved by removing all the unadsorbed free polymers from the bulk solution before introducing them to coat on the polymer coated core particles. Coating itself is estimated by monitoring change in the zeta potential of core-shell structure. The coating scheme as well as the characterization of these nanocomposite particles are discussed in detail. This processing scheme provides a simple way for the preparation of both bulk and surface coatings with these engineered nanostructured particles as building blocks.

Chemisorbed monolayers of decyltrichlorosilane, [11-(2-Naphthyl)undecyl]trichlorosilane, and a coadsorbed binary mixture of the two were prepared and subsequently investigated using lowangle x-ray reflectivity. Electron density profiles calculated from this data combined reveal well-defined naphthyl and alkyl regions in the [11-(2-Naphthyl)undecyl]trichlorosilane monolayer indicating a high degree of registry along the film normal. These conclusions are consistent with previous spectroscopic measurements of the same system.

The cleaning effectiveness of flowing hydrogen to remove oxygen (adsorbed and metal oxide) and carbon (elemental, carbides and carbon-hydrogen complex) from the surface of nanostructured alpha-iron and M50 type steel (Fe-Cr-Mo-V-C) alloy powders was investigated. The hydrogen treated powders and consolidated material were examined by bulk chemical analysis and metallographic examination. The trends in the cleaning effectiveness compared favorably with predictions from Richardson and Jeffies plots of metal-metal oxide equilibria.

We fabricated SiO2/Au nanocomposites using alternate sputtering method. The size of the Au particles seem was unchanged by the SiO2 sputtering and well controllable by the sputtering parameters. The nanoparticles in SiO2 were observed by TEM and the nanocomposites were characterized using XPS technique. TEM observation revealed the size of Au nanoparticles to be 2–15 nm. We observed a chemical shift of the Au4f peak in the XPS study. We demonstrate the efficiency of the technique for controlling the size and quantity of nanoparticles dispersed in nanocomposites.

The use of GaN/polymer nanocomposites in optoelectronics requires a perfect control of the GaN dispersion in the polymer matrix. This cannot be achieved without a good knowledge of the first atomic layer of the GaN nanoparticles. This paper reports the characterization of the surface chemical species of a GaN nanosized powder by diffuse reflectance infrared Fourier transform spectrometry.

We present an approach for synthesizing polymer matrices that have been pre-organized to bind metal ions selectively. The acyclic chelator, triethylenetetramine, was modified to include a polymerizable functional group and then complexed with a target metal ion. Unlike macro cyclic ligands, the acyclic chelators have the flexibility to form chelation rings that are dependent on metal-ion size and geometry. Therefore, we have used the complexation step as a means to optimize the chelator conformation for a particular metal ion. The resulting complex was then cross linked with the matrix monomer, TRIM (2-ethyl-2-(hydroxymethyl)propane-1,3-diol trimethacrylate), to provide a rigid polymer matrix for stabilization of the conformation for the metal-ligand site. These sites were then tested for selectivity towards the imprinted metal ion. Unlike imprinting for larger molecules, the relatively smaller size of the metal ions facilitated their access to the imprinted sites embedded in the porous polymers. In addition to metal-binding applications, polymeric materials doped with metal nanoparticles and metal ions can exhibit interesting physical, chemical, optical and electronic properties.

Preliminary rheological characterizations of aluminum nitride (AIN) nanoparticle suspensions in nonaqueous Newtonian fluid media, NMP and NMP/poly(amic acid) solutions, reveal marked differences in viscoelastic behavior, at relatively low dispersed phase volume fractions. Dynamic mechanical and steady shear measurements provide experimental evidence of the effective interparticle and polymer/particle interactions in a dispersion process of nonoxide nanoparticles for ceramic/polymer nanocomposites. The rheological nature of the nanoparticle suspensions corresponds to interparticle physicochemical interactions that have been previously concluded and discussed.

Direct images of the surface morphology of a series of the poly(styrene-b-butadiene-b-styrene) (SBS) ultrathin films have been obtained by atomic force microscopy (AFM). These films were formed under kinetic control. The resulting films consist of 25 nm-diameter spherical structures and/or cylindrical ones. These structures are surprisingly different fi-om alternative-lamellar structures which should be formed under annealed conditions because of the nearly equal length of two blocks of SBS. In nonselective solvents, the surface of the cast solution layer induces the copolymers to self-organize into micelle consisting of a polystyrene (PS) core and a polybutadiene (PB) shell in order to decrease film surface energy. The final structures depend on the property of the solvent used and filn-forming condition.

Copolymer latexes of poly(styrene/acrylic acid) were closely packed into two-dimensional arrays on glass, mica and silicon substrates respectively. When the small latexes were negatively charged due to −SO4− and −COO− groups on the surface, their film formation, in some degree, was affected by the electrostatic interaction between two particles as well as capillary force. Different electrolytes were added into the colloid to adjust the particle interaction so that the attractive and the repulsive forces were properly balanced and the ordered arrays were achieved. Thin metal film was deposited on the latex monolayer through thermal evaporation in vacuum. Then, the spheres were dissolved away to leave behind a surface with features located where the interstitial spaces between the densely packed spheres had been. This process depended upon the interaction between the microspheres and the substrates, and the adhesion between the film materials and the substrates. Different patterns of honeycomb net, triangle islands and separate spots can be obtained by controlling the ultrasonic time and intensity.

Solid sol of silver in poly(methyl methacrylate), Ag/PMMA, was prepared by bulk polymerization of methyl methacrylate solution of silver (I) triflluoroacetate (AgTfa) and followed by postheating. The formation of the metallic Ag nanocluster was characterized by visible spectroscopy, and effects of the concentrations of AIBN and AgTfa and the heat-treatment duration on the formation of Ag cluster were investigated. Furthermore, based on the kinetic study of MMA in the presence of AgTfa, possible mechanism for the reduction and agglomeration of silver is proposed.

Microparticles of poly(lactide) (PLac) and its copolymers with the amino acids, serine (P(Lac- Ser)), and aspartic acid (P(Lac-Asp)), respectively, were synthesized using the solvent evaporation microemulsion technique. Poly(vinyl alcohol) (PVA) was added as a non-ionic surfactant to stabilize the particles. The particle sizes are in the range of 200 nm. The surface of the particles was characterized by FTIR transmission spectroscopy under evacuation at room temperature and at 200°C. Hydroxy groups originating from PVA exist on the surfaces of the particles and they were observed at 3506 cm−1. Free hydroxy groups originating from the serine residue pendant to the copolymer P(Lac-Ser) backbone were observed at 3396 cm−1. Also, free carboxylic acid groups pendant to the copolymer P(Lac-Asp) backbone, originating from the aspartic acid residue, were observed at 3387 cm−1. The appearance of the free hydroxy or carboxylic acid groups in the IR spectra also showed that these hydrophilic functional groups moved to the surface of the particles in the process of microemulsion.

The effects of the surface silanol structure and interaction force between solid surfaces in water on the gel structure using acid catalyzed hydrolysis alkoxide-derived silica gels with various preparation conditions. The present study focused on the amount of catalysts and H2O/TEOS mole ratios. Surface silanol structure, interaction between solid surfaces and the structure in dried-gels were determined by a FT-nIR, FT-IR, Atomic Force Microscope (AFM) and a mercury porosimetry, respectively. As results, when a relatively low H2O/TEOS mole ratio ( from 4 to 40) was used, surface silanol was almost hydrogen bonded silanol, and isolated silanol disappeared. Since this hydrogen-bonded silanol formed a hydrogen bonded water layer on silica surface, short-range additional hydration force (less than 2 nm) appeared between solid surface and the tip of AFM. When H2O/TEOS mole ratio increase in the range from 20 to 40, the surface density of isolated silanol increased and that of residual Si-OC2H5 decreased. Relatively long-range additional repulsive force on these silica gels reached 20 nm from solid surface. The pore diameter in each dried gel almost corresponded to the surface distance, which acted the additional repulsive force.

Monolayers on surfaces have become a topic of considerable interest over the last few years. This has arisen from the need to functionalize a surface so that its properties are different than the properties of the bulk material. This research has involved functionalizing copper surfaces to enhance adhesion to epoxy. We have accomplished this using block copolymers made by Ring-Opening Metathesis Polymerization (ROMP). In this paper we discuss the synthesis and characterization of these block copolymers and their segregated monolayer conformation at copper surfaces, including NMR, GPC, SANS, neutron reflectivity, and TOF-SIMS. We also discuss a comparison of block copolymers to SAMS for surface functionalization.

Monolayers on surfaces have become a topic of considerable interest over the last few years. This has arisen from the need to functionalize a surface so that its properties are different than the properties of the bulk material. This research has involved functionalizing copper surfaces to enhance adhesion to epoxy. We have accomplished this using block copolymers made by Ring-Opening Metathesis Polymerization (ROMP). In this paper we discuss the synthesis and characterization of these block copolymers and their segregated monolayer conformation at copper surfaces, including NMR, GPC, SANS, neutron reflectivity, and TOF-SIMS. We also discuss a comparison of block copolymers to SAMS for surface functionalization.

To control the hetero-coagulation structure of ultra-fine γ-A12O3 and SiO2 powders for mullite ceramics, hetero-coagulation structures in suspensions with different pH conditions were investigated by experimental approach and computer simulation. Electrophoretic mobility distribution, which was determined by a Laser Doppler method, was used for the estimation of hetero-coagulation structure. As results, a bimodal electrophoretic mobility distribution was observed when precursor powders were prepared by colloidal mixing processes at pH=9.5. Since each peak almost corresponded to the electrophoretic mobility of γ-A12O3 or SiO2 particles, hetero-coagulates were not formed in suspension. In the case of pH=6.0, heterocoagulates generated in suspension, however, uniform and fine hetero-coagulates could not be attained. On the other hand, narrow and single mode electrophoretic mobility distribution was observed after colloidal mixing at pH=4.4. The change of hetero-coagulation structure with different pH conditions were analyzed by using Brownian dynamic methods with considering hetero-coagulated system. The change of hetero-coagulation structure with different pH conditions were qualitatively simulated by this model.

Nanostructured yttrium stabilized zirconia powders with yttria concentrations between 0.0 and 10.0 mol % were prepared via an aqueous chemical synthesis route. This synthesis involved the spray atomization of the aqueous solution mixture of zirconyl chloride and yttrium chloride into a reaction vessel that contained a diluted ammonium hydroxide, followed by ultrasonication, separation and heat treatment. These powders were characterized using SEM, TEM, XRD, and chemical analysis. The crystalline structure was refined using the Rietveld technique. At temperatures below 200 °C, the powders were amorphous solid solutions with an structure independent of yttria concentration, where yttrium atoms occupied the zirconium positions in the zirconyl group, e.g., (Zr4(1-x) Y4x(OH)8(OH2)16)(8-4x)+. Annealing the sample at 400 °C, the amorphous phases crystallized into monoclinic, tetragonal or cubic nanocrystalline zirconia, depending on yttria concentration, where the non-doped samples had a mixture of monoclinic and tetragonal phases.

We have investigated the kinetic role of a surfactant in the epitaxial crystal growth of Si/Ge using an ab initio molecular dynamics approach. We find that adsorption and diffusion of an adatom on monohydride Si(001) surface is drastically altered from that on a clean surface in several ways. We particularly emphasize the role of H as a surfactant, and this is further compared to typical group V materials.

The arival on the market of new therapeutic and antigenic molecules requires the development of appropriate delivery systems. The design of injectable nanoparticulate drug caniers invisible to the mononuclear phagocyte system is a major challenge. Also, overcoming mucosa baniers, such as the nasal one, using biodegradable nanospheres is another strategy still to be explored. These routes of administration require nanoparticulate systems with optimized surface properties. We investigated the ability of polyethylene glycol (PEG)-coated nanospheres made of amphiphilic diblock copolymers to achieve these goals. After an optimization of the nanosphere surface properties, we studied the possibility of entrapping macromolecules within the PEG-coated nanospheres. Results showed that it is possible to encapsulate a model protein, human serum albumin (HSA) within monodisperse nanospheres of a mean diameter of about 200 nm, reaching loadings as high as 9% (w/w). Moreover, these nanospheres showed excellent abilities for the transport of a model antigen, tetanus toxoid (Tr) through the nasal mucosa.