Gradient arrays are now common tools in combinatorial chemistry for discovery of new leads to commercial materials. Although the cost per sample has dropped markedly with new high throughput methods, efficient use of experimental resources is still important. Examination of gradient arrays from an informational standpoint suggests that designs which use the concepts of sphere packing and covering will be more efficient than simple gradients. This is especially true in higher dimensional systems.

Combinatorial electropolymerization with electrical addressing was realized on the array of 96 electrode groups, each from four electrodes. The polymer synthesis was combined with subsequent high-throughput investigation of analytical properties of synthesized polymers. Two-and four-point techniques were applied simultaneously to measure electrical properties of synthesized polymers and contact resistances between electrodes and polymers and modifications of these parameters on addition of analyte. The system was used for development of sensitive materials for detection of gaseous hydrogen chloride.

A new magneto-optical (MO) imaging system for high-throughput characterization of combinatorial magnetic thin films has been developed. The instrument allows us to measure both Faraday rotation and ellipticity maps at various wavelengths (400 nm∼1000 nm), different magnetic fields (0∼2000 G), and different temperatures (12 K∼300 K) for wide variety of materials. We used the magnetic circular dichroism (MCD) modulation technique to map MO properties, relatively free from substrate effects. The superiority of this system is that magnetic hysteresis curves of numerous specimens with different compositions prepared by the combinatorial technique can be simultaneously measured at one sweep of magnetic field, providing an efficient characterization method for combinatorial magnetic materials. We also confirmed that the system possesses enough spatial resolution and sensitivity for detecting MO signals of individual pixels contained in a combinatorial library.

Micro X-ray fluorescence is used as a high-throughput screening method for combinatorial applications. These include chemical weapon degradation products, catalytic phosphate hydrolysis and radiologic dispersion device metals. In each application the intrinsic elemental signature was utilized to identify the lead hits for the combinatorial screening in locating peptide sequences exhibiting the desired binding characteristics. In addition to being nondestructive, rapid and non-perturbing to the binding event, this method can be used to quantify the amount of target material.

We have developed an empirical method to model bioresponse to the surfaces of biodegradable polymers in a combinatorial library using Artificial Neural Networks (ANN) in conjunction with molecular modeling and machine learning methodology. We validated the procedure by modeling human fibrinogen adsorption to 22 structurally distinct polymers. Subsequently, the method was used to model the more complicated phenomena of rat lung fibroblast and normal human fetal foreskin fibroblast proliferation in the presence of 24 and 44 different polymers, respectively. In each case, the root mean square (rms) percent error of the prediction was substantially less than the experimental variation, showing that the models can distinguish high and low performing polymers based on structure/property information. Using this method to screen candidate materials in terms of specific bioresponse prior to extensive experimental testing will greatly facilitate materials development for biomedical applications.

A modified low-pressure chemical vapor deposition reactor was used to create compositional spreads of MO2/SiO2 films (M = Hf, Zr and Sn) using tri(t-butoxy) silanol and anhydrous metal nitrates of hafnium, zirconium and tin at temperatures below 250 °C. The compositional spreads formed by this process were characterized by ellipsometry and Rutherford backscattering spectrometry. A survey of possible reactions involved in the deposition is included.

Coupling of combinatorial chemistry methods with high-throughput (HT) performance testing and measurements of resulting properties has provided a powerful set of tools for the 10-fold accelerated discovery of new high-performance coating materials for automotive applications. This approach replaces labor-intensive steps with automated systems for evaluation of adhesion of 8 × 6 arrays of coating elements that are discretely deposited on a single 9 × 12 cm plastic substrate. Performance of coatings is evaluated with respect to their resistance to adhesion loss. This parameter is one primary consideration in end-use automotive applications. Coating leads identified from the HT screening have been validated on the traditional scale. Details of these validation studies are discussed.

Combinatorial methods bring about plentiful data not only in size but also in dimension. To handle multi-dimensional data easily, a virtual container of combinatorially acquired data is developed which is called “virtual sample libraries” (VSL). VSL stores the data hierarchically in the order of (1) coordinates in the sample library, (2) names of the measurements performed, and (3) data obtained from each measurement. Thus, the loads for analysis and visualization of multi-dimensional data are reduced because the stored data can be accessed intuitively, that is, just by tracing the hierarchy structure. This framework is easily constructed by the aid of object-oriented script language which is good at describing complicated data structure. Visualization of combinatorially acquired 7-dimensional data is demonstrated.

A method of preparing ternary alloy libraries for combinatorial materials development based on thick film deposition and interdiffusion was studied, using the Ni-Fe-Cr ternary system. Specimens were prepared by depositing films onto sapphire substrates with an e-beam evaporation system followed by annealing in a vacuum for interdiffusion. The specimens were examined using cross sectional scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), scanning Auger microanalysis (SAM), angular resolved x-ray fluorescence (AR-XRF), x-ray diffraction (XRD), and nanoindentation. The method proved an effective way to make the alloy libraries for screening mechanical properties by means of nanoindentation.

We have fabricated thin-film combinatorial gas sensor libraries based on doped semiconducting SnO2 thin films. The utility of combinatorial libraries is two-fold: one is to search and optimize the compositions for high sensitivity and selectivity of gases, and the other is to make use of the natural array geometry of the libraries with different sensor elements for electronic noses. Combinatorial pulsed-laser ablation was used to deposit compositionally varying arrays of sensor elements onto a pre-patterned device electrode configuration. Using a multiplexing electronics, we have demonstrated detection of chloroform, formaldehyde, and benzene gases at concentrations down to 12.5 ppm through pattern recognition of signals from the arrays of sensors.

Various combinatorial matrix arrays of UV-violet, white, and blue-to-red organic light-emitting devices (OLEDs), fabricated using a sliding shutter technique, are described. In the UV-violet devices, which contain a UV-violet emitting layer of 4,4′-bis(9-carbazolyl) biphenyl (CBP), the optimal radiance R and external quantum efficiency ηext were determined with respect to the thicknesses of the hole transporting layers. In the blue-to-red devices, which contained a blue-emitting layer of 4,4′-bis(2,2′-diphenyl-vinyl) -1,1′-biphenyl (DPVBi) and a red-emitting 5 wt.% dye-doped guest-host layer, the color of the devices evolved continuously from blue to red as the thickness of the doped layer increased from 0 to 35 Å. The (nominal) 2 Å-thick doped layer device exhibited the highest brightness L ∼ 120 Cd/m2 and external quantum efficiency ηext ∼4.4 % at a current density of 1 mA/cm2. In the white OLEDs, which were similar to the blue-to-red devices but with lightly doped emission layer, the highest brightness Lmax was over 74,000 Cd/m2; in all devices Lmax exceeded 50,000 Cd/m2. The maximum efficiencies were 11.0 Cd/A, 5.96 lm/W and 4.6% at 5.8 V, 0.6 mA/cm2, and 68 Cd/m2 in a 0.25 wt.%, 2 nm-thick doped layer device.

A quaternary rare-earth intermetallic compound La3Co29Si4B10 has been synthesized and the crystal and magnetic structures investigated by neutron diffraction over the temperature range 7–300 K. Rietveld refinements of the neutron diffraction patterns demonstrate that La3Co29Si4B10 is tetragonal and isostructural with Nd3Ni29Si4B10. The magnetic scattering indicates that the moments of the Co sublattice are collinear and lie in the basal plane. The mean magnetic moment for the Co atoms is μ ∼ 0.5 μB, or 13.6μB/F.U., in agreement with magnetization measurements.

In combinatorial chemistry, most libraries are prepared according to solid-phase synthesis strategies using resins or pins. Although synthesis and purification steps are facilitated, reaction monitoring presents difficulties. Since the polymeric support is not soluble, an analytical method able to cope with a solid sample is thus required to perform direct identification of the anchored molecules without any chemical treatment. Static-Secondary Ion Mass Spectrometry (S-SIMS) was investigated in that purpose. Positive and negative ion mass spectra were acquired to identify single beads whereas mixtures (Mix and Split libraries or pooled beads issued from different batches) were profiled through imaging experiments.

Combinatorial strategies are applied to surface polymerization by ion assisted deposition (SPIAD) for the production of polythiophene films. Thiophene ion energy in the range of 25–200 eV and ion to α-terthiophene neutral ratio are varied to tune the extent of surface polymerization and film photoluminescence. SPIAD polythiophene films are grown by both mass-selected and non-mass-selected ions, while x-ray photoelectron spectroscopy and surface mass spectrometry are applied to determine film chemistry and the extent of polymerization. This work demonstrates that ion kinetic energy and ion to neutral ratio can be varied over a wide range in SPIAD to select films with useful optical or electronic properties. The essentially combinatorial approach of SPIAD can be dramatically extended by use of new ions and/or neutral species.

A reactor was designed, built and successfully operated that allowed the simultaneous running of 96 independent reactions at steady-state. Since the problem involved the attainment of 98% in selectivity from a starting point of 93%, very precise reproducibility in selectivity was required. Because selectivity varies with time in a batch reactor, and since commercial reactors for this process are continuous, continuous reactors operated at steady-state were required. Longterm standard deviation in selectivity of <0.2% was attained. Information feedback from so many reactors allowed study of variation in catalyst composition, liquid retention times, space velocity, temperature and other variables to be accomplished in relatively short time. Comparison between heterogeneous and homogeneous catalysis in the same reactors gave insight into the underlying mechanisms determining activity and selectivity. Results from 200 uL reactors scaled very well to laboratory and pilot plant sizes.

The identification of appropriate reaction models is very helpful for developing chemical vapor deposition (CVD) processes. In this paper we propose a novel system to analyze experimental data of various CVD reactors and identify reaction models automatically using Genetic Algorithms (GA) with multiple process simulators and modeled functions. We demonstrate that this system is able to adequately model reaction systems, and that complex analysis of various experimental data increased the reliability of the reaction modeling results.

Syntheses carried out on soluble polymers, such as polyethylene glycol (PEG), benefit the advantages of both solution-phase and solid-phase syntheses. The choice of the reaction solvent governs the polymer solubility. Synthetic steps are conducted under homogeneous conditions whereas purifications are performed by filtration after polymer precipitation. This alternative strategy, known as liquid-phase chemistry, has been investigated to prepare combinatorial libraries.

The fact that soluble polymer supported molecules are directly amenable to standard spectroscopic methods, including NMR (1H, 13C) and ESI or MALDI mass spectrometry (ElectroSpray and Matrix Assisted Laser Desorption Ionization) allows to perform to in situ reaction monitoring without the need to release the compound from the polymeric support.

We report a general methodology to characterize step by step soluble polymer supported organic molecules by MALDI and ESI mass spectrometry. High throughput analyses were targeted to fullfil combinatorial chemistry requirements. Data acquisition and interpretation were automated through the design of specific experimental protocols and a data managment software. MALDI mass spectrometry was appropriate to analyze pure supported molecules whereas ESI mass spectrometry coupled to liquid chromatography was required to unravel PEG mixtures.

Standard machine-learning algorithms were used to build models capable of predicting the molecular weights of polymers generated by a homogeneous catalyst. Using descriptors calculated from only the two-dimensional structures of the ligands, the average accuracy of the models on an external validation data set was approximately 70%. Because the models show no bias and perform significantly better than equivalent models built using randomized data, we conclude that they learned useful rules and did not overfit the data.

A method yielding precisely controlled thickness profiles in thin-film growth is necessary for continuous compositional spread techniques. While multiple approaches have been introduced and successfully tested, some specific applications require the use of very thin “wedge”-type profiles (∼10 Å at the thickest point), while at the same time yielding lateral sample sizes of several centimeters. Here we introduce the basic principles of a pulsed-laser deposition based approach utilizing the translation of the substrate behind a slit-shaped aperture and demonstrate by simple calculations that this method can satisfy these requirements.

Our efforts to combine the combinatorial technology and microstructure analysis to develop catalysts for proton exchange membrane fuel cell (PEMFC) technology have been described. This offers the realization of “materiomics” in comprehensive material research. Catalyst technologies are indispensable for wide use of PEMFC, which are regarded as the low emission and highly efficient energy conversion device for the next generation. We have applied the combinatorial method for the hydrogen production and/or purification of catalysts, and anode catalyst investigations. The catalyst library consisting of precious metals loaded on various metal oxides was tested for water gas shift reaction and steam reforming of methanol and/or DME. Various metal oxides added to platinum loaded on carbon were screened for anode catalysts. The microstructure of each catalyst was analyzed by employing scanning electron and/or transmission electron microscopy. This paper mainly describes the catalysis screening results of above reactions that form a part of “materiomics”.