Bret Ja Chisholm

Combinatorial and high-throughput screening of materials libraries: Review of state of the art

Rational materials design based on prior knowledge is attractive because it promises to avoid time-consuming synthesis and testing of numerous materials candidates. However with the increase of complexity of materials, the scientific ability for the rational materials design becomes progressively limited. As a result of this complexity, combinatorial and high-throughput (CHT) experimentation in materials science has been recognized as a new scientific approach to generate new knowledge. This review demonstrates the broad applicability of CHT experimentation technologies in discovery and optimization of new materials. We discuss general principles of CHT materials screening, followed by the detailed discussion of high-throughput materials characterization approaches, advances in data analysis/mining, and new materials developments facilitated by CHT experimentation. We critically analyze results of materials development in the areas most impacted by the CHT approaches, such as catalysis, electronic and functional materials, polymer-based industrial coatings, sensing materials, and biomaterials.

Combinatorial chemistry methods for coating development V: generating a combinatorial array of uniform coatings samples

Abstract Combinatorial methods have proven to be valuable tools for the development of new compounds, catalysts, and electronic materials. We have developed a combinatorial factory capable of preparing and evaluating about 100 organic clear coatings in a day. Successful application of combinatorial methods to coatings development requires rapid and uniform preparation of a large number of diverse coatings. We have found that centrifugal spin casting is an effective method of producing an array of 48 coatings samples, each 9xa0mm diameter. The uniformity and flatness of each sample is dependent on specific process details such as protection from air currents and control of the evaporation process to avoid the “coffee ring effect”.

Combinatorial chemistry methods for coating development: III. Development of a high throughput screening method for abrasion resistance: correlation with conventional methods and the effects of abrasion mechanism

Combinatorial chemistry has proven to be a valuable tool for the development of new compounds. In the pharmaceutical industry, where combinatorial chemistry began, the approach has been instrumental in the high-speed development of new drugs. Due to the overwhelming success of the combinatorial methodology in the pharmaceutical industry, it has been recently applied to materials development. We have developed a combinatorial factory capable of preparing and evaluating of the order of 100 organic clear coatings per day. One of the most challenging aspects of the creation of the combinatorial factory was the development of the high throughput screening (HTS) methods for determining the primary properties of interest such as optical clarity, abrasion resistance, adhesion, and weatherability. For each property, an entirely new method was developed that allowed for rapid measurement on very small samples. This paper describes, in detail, some of the results obtained during the development of an HTS method for abrasion resistance. In particular, this document illustrates the importance of understanding the mechanism of abrasion and its influence on the measurement of abrasion resistance.

Combinatorial chemistry methods for coating development: V. The importance of understanding process capability

A combinatorial method for the development of organic clear coatings for plastic substrates has been developed. The combinatorial process possesses all the aspects of a conventional combinatorial process such as automated sample preparation, miniaturized samples configured in an array format, high throughput screening (HTS) of the properties of interest, and computer software developed for data management, storage, and analysis. The combinatorial factory has greatly enhanced the rate of organic clear coat development. A very important activity involved in the development of the combinatorial factory was the determination of process capability for each component of the factory. A good understanding of process capability and sources of variability was required to obtain high quality, reliable data.

Synthesis and Characterization of PS-PIB-PS Triblock Copolymers

Abstract Poly(styrene-isobutylene-styrene) (PS-PIB-PS) block copolymers synthesized via living carbocationic polymerization using a di- or tricumyl chloride/TiCl4/pyridine initiating system in 60/40 (v/v) hexane/methyl chloride cosolvents. The kinetics of formation of the PIB block at − 80°C were found to be first order in isobutylene (IB) concentration, first order in the concentration of initiating sites, second order in TaiCl4 concentration, and a negative fractional order with respect to the pyridine concentration. The rate of polymerization was found to decrease with increasing temperature, indicating an equilibrium between dormant, covalent and active, ionized chain ends, and chain-end concentration studies suggested that there was no contribution by free ions to the rate of propagation. Diagnosis of the livingness of the IB polymerization indicated that at high (≥90%) monomer conversion, β-proton elimination becomes important, causing the timing of addition of styrene to be critical. Addition of st...

High-Throughput Adhesion Evaluation and Scale-up of Combinatorial Leads of Organic Protective Coatings

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.