We have demonstrated a method to rapidly and reliably fabricate arrays based on the self-assembled morphology of block copolymer ultra thin films. An ordered, nanoporous structure obtained from the block copolymer thin films is used a template for the subsequent electrodeposition of conducting polymer nanomushrooms of polypyrrole (PPy). The influence of current density, deposition charge and morphology of the templates and nanostructured conducting polymer coatings has been investigated. The electrical properties of the polymer coatings were studied.

Learning how to purify and manipulate single wall carbon nanotubes (SWNTs) presents a unique challenge in material science. The processing-related difficulties of these long nano-fibers stem from their high aspect ratio, rigidity and the profound hydrophobic attractions along their tubular walls. Shortening them into discrete segments, with lengths from tens to hundreds of nanometers, presents a viable methodology to alleviate the shape-induced intractability. In addition, the metal-assisted self-organization of these nanosized objects into nano-forest geometries with dense perpendicular surface grafting, demonstrates that such nanosized objects hold significant promise for the development of nanoscale devices. This paper will present an extensive characterization of the topological characteristics of these assemblies, along with their surface coverage, growth characteristics and height fluctuation on iron hydroxide substrates.

Homopolymer and block copolymer brushes grafted from Au and Si (SiOx) surfaces via living anionic surface initiated polymerization (LASIP) has been reported. 1,1-diphenylethylene (DPE) derivative, an initiator for anionic polymerization, was grafted onto planar Si-wafer and Au surfaces by self-assembled monolayer (SAM) techniques. n-BuLi was used to activate the DPE for anionic polymerization of monomers at the interface under high vacuum. By a careful sequence of monomer introduction, reaction, and termination, homopolymer and block copolymer tethered polymer brushes were obtained. The importance of initiator activation, control of polymerization conditions, and removal of excess BuLi is emphasized. Interesting differences in morphology, thickness, grafting density, and polymerization conditions contrasts LASIP from solution and other surface initiated polymerization (SIP) mechanisms. The formation of block copolymer sequences highlights the unique utility of a living anionic polymerization technique on surfaces.

This paper reports on the influence of the field-effect mobility of transistors based on regioregular head-to-tail coupled poly (3-hexylthiophene) by mechanically induced alignment on differently treated insulator surfaces. It is demonstrated that on hydrophilic insulator surfaces mechanical rubbing of the polyhexylthiophene layers perpendicular to the source drain contacts can increase the field-effect mobility whereas rubbing parallel to the source drain contacts results in a reduced mobility. In contrast it is shown that in transistors with a hydrophobic insulator surfaces, which show much higher mobilities no further improvement can be achieved. The rubbing induced polymer alignment is deduced from optically polarized transmission spectroscopy on polymer-coated quartz glass substrates. The different behavior of the field-effect mobility will be explained in terms of different degrees of crystallinity.

Delamination of organic coatings from metal surfaces can occur in a number of different ways, e.g. as pure cathodic delamination, as Filiform corrosion or a mixture of these. In fact, in most technical systems the pure cases are the exception and, of course, delamination is usually very slow. It has been shown that in fast delaminating systems the length scales may range between several 100 μm and several millimetres, while in systems which show slow delamination the reaction zones can be confined to submicroscopic distances [1]. This underlines the importance of investigation methods with submicroscopic resolution. As a very promising new technique Scanning Kelvin Probe Force Microscopy (SKPFM) was applied for the investigation of cathodic delamination and filiform corrosion on a submicroscopic scale [1, 2]. Indeed, these first investigations have shown that SKPFM gives basically the same information as the standard Scanning Kelvin Probe (SKP), but with a much improved resolution. It could be shown, for instance, that the extension of the reaction zone seems to be much narrower than would have to be assumed from the SKP measurements. Based on the knowledge about the different delamination types that was obtained from investigations with the standard SKP [3–12] the SKPFM should be the ideal tool to get information on the submicroscopic scale. However, SKPFM alone is not sufficient for revealing the underlying fundamental mechanisms; of even higher importance is the knowledge of the molecular and mesoscopic structure at the buried interface. In this paper a design for suitable model samples is proposed and first results are presented.

We report on the recent progress of our continued effort for the preparation and characterization of well oriented films of tetratetracontane (n-C44H90) and perfluorotetracosane (n-C24F50), which are good model molecules of fundamental polymers, polyethylene (CH2)n and poly(tetrafluoroethylen) (CF2)n, vacuum-deposited on metal surfaces. When the surface of the metal substrate was oxidized, the deposited chain molecules are aligned with their molecular axes vertically standing on the surface, while they lie flat on the surface when atomically clean Cu(100) surface was used. In the case of n-C44H90 on Cu (100), low-energy electron diffraction (LEED) studies revealed that the molecules were also azimuthally aligned with the chain axis almost parallel with the <100> and <010> axis, and infrared reflection-absorption spectroscopy (IR-RAS) enabled detailed studies of the film structure at increasing film thickness._By applying the technique of angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) to these flat-lying molecules, the intramolecular energy-band dispersion relation could be determined, The results agreed well with the results deduced from the previous work using vertically standing molecules assuming an inner potential V0. of –5 eV, confirming the validity of the estimation of V0. Excellent agreement was found between the observed and simulated spectra using the independent-atomic-center (IAC) approximation. Also the value of the vacuum level shift by molecular deposition was deduced for TTC/Cu(100) system to be – 0.3 eV. As for n-C24F50, the E(k) relation deduced in our previous study using vertically standing molecules showed discrepancy with band calculations. The detailed reexamination of the experimental data using IAC calculations for the previous report gave more realistic estimation of V0, and the newly deduced E(k) relation using this data showed good correspondence with theoretical band calculations, thus removing the difficulty in the previous work.

The current design of implants or implant materials is under the pressure of an increasing demand. In our society we find more and more active older people with an increasing life time. On the other hand it can be observed that also for younger people implants become more and more necessary due to sport or accidents. As a consequence the development of new surgery strategies as well as new materials systems is needed. In this work we present the idea of creating a metal implant surface which mimics a cell membrane or at least parts of it. Scanning electron and atomic force microscopy investigations show that a multilamellar closed lipid layer can be prepared and that this layer resembles the same contact angle observed for the membrane of an osteoblast.

Highly conducting thin films of C60 were deposited by thermal evaporation in high vacuum on single crystal silicon substrates. The microstructure of the films was characterized by using Atomic Force Microscopy, and laser Raman spectroscopy. The films were polymerized by uv irradiation. The dc electrical resistivities of the as-deposited and uv-polymerized films were measured as functions of temperature between 295 and 17K by the four-probe technique. We present results on the effects of uv-irradiation on the surface microstructure and the temperature dependence of the electrical resistivity of these films.

Alkylacrylate compounds were deposited by the ionization-assisted deposition (IAD) method to form thin films of comb-like polymers having long alkyl side chains on the vinyl polymer backbone. From the source material of n-octadecyl acrylate, polymer thin films having average molecular weight of 6000 were obtained at the polymer yield of 45 to 65%. For the preparation of fluorinated polymer thin films, 1H, 1H, 11H-eicosafluoroundecyl acrylate was used as the source material. Although the conventional evaporation method could not accumulate any films with this material, the IAD was able to produce insoluble thin films that have large contact angle against water droplet. In either material, the polymerization reaction was enhanced with increasing electron emission current for IAD. These results indicate that the IAD enables the preparation of thin polymer coatings that have polyethylene or Teflon-like properties without using the solvents.

Two kinds of dendrimers, DAB and PAMAM (with the same terminal groups but different branched repeat units), were chosen as interlayers for Cu ultrathin films deposited on native oxide Si(100) wafers. 10 nm Cu thin films were deposited directly on the dendrimer monolayers by DC sputtering at room temperature. The nanomechanical results show that PAMAM and DAB have significant effects on the properties of the resulting films, with the DAB layer acting as a stiffer ‘spring’, compared to PAMAM, underneath the Cu films. Both dendrimer interlayers lower the hardness of the film, compared to Cu alone; the effect is greater for PAMAM than DAB interlayers. However, the introduction of either dendrimer monolayer significantly increased the elasticity of the Cu film.

Flat porphyrin molecules have been linked at right angles, using metal atoms, to create square or open-ended box structures having minimum cavity widths of about 2.4 nm and nominal volumes of ca. 14 nm3. Chemically modified versions of the squares feature reactive hydroxyl groups at the top and bottom of each of the four walls of the box structure. These groups combine readily with acid chloride functionalized molecules to yield robust ester linkages. If the reactions are carried out at a liquid-liquid interface with squares in one layer and difunctional acid chloride linkers in the other, polymer formation occurs at the interface. As with other liquid-liquid interfacial polymerizations, the reaction is self-limiting because transport of reactants is inhibited by membrane formation. Polymer films prepared by this method have controllable thicknesses ranging from about 200 nm to 2 microns. The membranes display size-selective porosity with respect to molecules smaller than the intra-square cavity and blocking behavior with respect to larger molecules. Electrochemical and electrochemiluminescence methods are used to measure qualitative and quantitative sieving behavior by employing a conductive metal or ceramic electrode as an underlying platform. In these and related membranes, selective molecular transport is being engineered for applications such as chemical sensing, energy conversion, and chemical catalysis.

Compressed CO2 is employed as the solvent for the deposition of polymers onto patterned surfaces created by a lithographic technique. This deposition technique should have wide applicability in the deposition of organic and polymeric materials for optoelectronic devices. The advantage of controlled deposition confers a further benefit in the control of the patterned surface. In a specific example a perfluorinated polymer was dissolved in liquid carbon dioxide. The polymer solution was deposited by use of a nozzle onto a pre-patterned surface. The resulting polymer film showed a clear image of the original pattern as measured by optical microscopy.

We examined blood compatibility of titanium oxide layer on stainless-steel (SUS316L). The oxide layers with varied thickness were yielded on SUS316L plates by dip-coating of sol-gel solution starting from tetraethyltitanate. The blood compatibility was evaluated in term of platelet adhesion using platelet rich plasma. With increase in the thickness of the oxide layer, the number of adherent platelets decreased rapidly, reached minimum around 150nm. This indicated that the thickness of titanium oxide layer affected platelet adhesion.

New metal powders containing organic thin film layer with multi-functional properties are prepared and used in the manufacturing of anisotropic conductive film (ACF) material for electronic package application. The organic thin film layer possesses both insulating property and thermo-compressed flowable property. The former insulating property ensures metal powder to have good insulation property at room temperature, and the latter thermo-compressed flowable property maintains the electric conductance of ACF material after high temperature compression process. Besides, the organic thin film layer also exhibited good steric hindrance to enhance the dispersion and anti-settling of metal powers in resin matrix. The functional organic groups on the surface thin film will also improve the interface adhesion between metal powder and resin matrix. Such metal powder with surface chemical modification is suitable for electronic material application, for example, anisotropic conductive film (ACF).

Non-contact Atomic Force Microscopy (AFM) was used to study the embedding of 10 nm and 20 nm gold nano-particles into the surface of polystyrene films spin-coated onto silicon substrates. The rate of embedding was determined by measuring the apparent nanosphere height as a function of annealing time. This was accomplished by two different methods. In the first case, each image (after a specific annealing time) is acquired at a different spot on the sample surface. In this case a fairly large (∼40) number of particles were imaged in order to have acceptable statistics. A second method involved the use of a kinematic mounting hot stage that allowed the same spot on the sample to be imaged at each time. This allows the same final precision without the same necessity for imaging large numbers of particles. The results indicate that sub nm resolution is easily obtainable with either technique.

Copper-doped carbon aerogels, which were prepared by sol-gel polymerization of a mixture of resorcinol, formaldehyde and copper ions, followed by supercritical drying with liquid CO2 and carbonization at different temperatures under a N2 atmosphere, were characterized by magnetic susceptibility and temperature-dependent conductivity measurements. The experimental results show that the magnetic susceptibilities (χ) of all the copper-doped carbon aerogels are larger than that of the blank carbon aerogel. The temperature-dependent magnetic susceptibilities of the copper-doped carbon aerogels are well fit to a Curie function in the low temperature region (below 45 K). According to the Curie constant obtained, the spin concentration (N) of the copper-doped carbon aerogels was calculated and the results show that the spin concentration of doped samples increases at first with an increase in the copper concentration used in doping, and then drops from the maximum in N and χ when the copper concentration is further increased above 0.1 wt%. Magnetic susceptibility results suggest that copper-doped carbon aerogels carbonized at 800 °C are more disordered than those carbonized at 1000 °C. The conductivity of these copper-doped carbon aerogels is apparently higher than that of the blank carbon aerogel, especially at low temperature (T < 45 K). The temperature-dependent resistivities of both the copper-doped and the blank carbon aerogels follow a linear functional form log ρ(T) ∼ (1/T)1/2 with two distinct regions below and above 45 K, indicating that the conduction of both the copper-doped and the blank carbon aerogels obey a tunneling and/or a hopping mechanism.

We propose a new method of optically fabricating kinoforms using polyester containing cyanoazobenzene units in the side chain. This method utilizes the surface relief structures induced optically on the azopolymer films. Using a gray-tone amplitude mask with black and white lines as a spatial light modulator, we constructed the surface relief structures on the azopolymer films with an argon-ion laser beam (488nm). The relief depths constructed were deep enough to provide a wide range of visible light with a phase difference of 2π. In addition, irradiation on the azopolymer film with a spatially modulated light that had multilevel intensities inscribed the multilevel relief structure reflecting the intensity modulation. This property is applicable to the fabrication of diffractive optical elements, especially kinoforms, because the multilevel relief structure provides an incident light with phase modulation. We designed a phase pattern for a kinoform by computation and expressed it as a gray-tone amplitude mask. Irradiation on the film through the gray-tone mask with the pump beam inscribed a multilevel relief structure that diffracted an incident light to produce a desired image. The desired image appeared without the effect of the internal refractive index modulation of the film. We, therefore, confirmed a possibility of fabricating a kinoform with a multilevel relief structure on the azopolymer film. Since our fabrication method for kinoforms requires only exposure, it has a significant advantage over other techniques that require additional processes such as developing and etching.

It has been theoretically predicted that a polymer chain in poor solvent conditions undergoes a phase transition from a collapsed globule to a stretched coil. In this paper, we present force-distance curves, obtained by atomic force microscopy (AFM), showing the characteristic forceplateau associated with this transition. We show that the magnitude of the force depends on the environment (interfacial energy) that the stretched coil experiences when it is pulled-out as it is predicted by the theory.

Several nylon nanocomposites was prepared using pristine and organically modified silicates. DSC and XRD reveal that the metastable γ phase is stabilized in the nanocomposites and the amount of γ phase scales with the silicate loading. Both storage and loss moduli of the nanocomposites increase with increasing silicate content. The overall characteristics of these systems become more solid-like before the onset of the glass transition. The increases in moduli are most pronounced in the rubbery regime. Pristine silicates have marginal effect on the mechanical response due to poor dispersion and/or lack of interactions with the polymer matrix.

The three-year collaboration between Simmons College and the Cornell Center for Materials Research (CCMR) is focused on undergraduate student/faculty research in organic light emitting diodes (OLEDs). The physics of OLED devices is characterized by three major processes: charge injection, charge transfer, and light emission as a result of the electron-hole recombination. In the first year of the program our research has been related to the first two stages.

OLEDs based on small molecule as well as polymeric layers have been investigated. The devices were prepared using mostly aluminum (also nickel and iron) as electrodes and PC:TPD or polythiophene as the organic layer. Electrodes of about 20 nm were formed by vacuum evaporation, and organic layers of approximately 100–200 nm were spin-coated. The current-voltage characteristics, measured under forward and reverse bias up to 10 volts, demonstrate typical semiconductor S-shape behavior, and show variations dependent on aging, thickness of the polymer layer, and type and combination of electrodes.

The results presented here specifically track the degradation of devices using polythiophene sandwiched between aluminum electrodes. The I-V curves and successive current response as a function of time and under constant voltage drive are presented along with complementary mass spectra and UV-visible and infrared absorption spectra. These measurements along with preliminary computer modeling of HOMO and LUMO energies for a series of thiophene oligomers suggest a correlation between internal changes in the polymer and variations in the electrical characteristics of the devices.