High‐Output Polymer Screening: Exploiting Combinatorial Chemistry and Data Mining Tools in Catalyst and Polymer Development

High‐output polymer screening (HOPS) combines automated polymerization with online reaction monitoring, rapid polymer characterization and novel fingerprint technology useful in polymer preparation as well as polymer processing and polymer additive development. Originally, HOPS was introduced to develop polymerization catalysts and polyolefin materials more effectively. In comparison to conventional high‐throughput screening, focusing on ultrahigh speed of catalyst screening using arrays of miniaturized reactors, output‐oriented, process‐relevant HOPS is aiming at generating and exploiting high information density (useful information/experiment). Catalyst systems for olefin polymerization are evaluated in automated workstations with multiparallel as well as semi‐ and fully automated, upgraded lab reactors. Automated polymerizations under standardized conditions afford large families of well‐characterized polymers which serve as calibration samples for data analysis. Data analysis, using multivariate calibration, is the key to basic correlations between spectroscopic information and catalyst and polymer properties as well as reaction parameters and processing conditions. IR spectroscopic fingerprints are used to measure chemical copolymer composition, density, molecular weight as well as thermal and even mechanical properties. This fingerprint technology can be applied in online quality control and facilitates transfer from lab results into pilot and production plants. Fingerprint methods are important components of rapid online analysis and can reduce the need for time‐ and money‐consuming polymer testing.

Fingerprint technology combines spectroscopic analysis by means of “cheap” spectrometers with multivariate calibration.     

α-olefin oligomers with narrow molar mass distributions from zirconocene/methylaluminoxane catalysts — An examination of the structure-reactivity relationship

A series of tert-butyl substituted zirconocene/methylaluminoxane catalysts illustrates the potential for the tailoring of olefin oligomers with extremely narrow molar mass distributions, which are explained on the basis of a chain-length dependent propagation rate. Comparative oligomerization experiments provide a means to estimate the relative rates for chain propagation versus chain transfer as well as a correlation with the metallocene structure.     

Geometric Spin Hall Effect of Light at polarizing interfaces

The geometric Spin Hall Effect of Light (geometric SHEL) amounts to a polarization-dependent positional shift when a light beam is observed from a reference frame tilted with respect to its direction of propagation. Motivated by this intriguing phenomenon, the energy density of the light beam is decomposed into its Cartesian components in the tilted reference frame. This illustrates the occurrence of the characteristic shift and the significance of the effective response function of the detector. We introduce the concept of a tilted polarizing interface and provide a scheme for its experimental implementation. A light beam passing through such an interface undergoes a shift resembling the original geometric SHEL in a tilted reference frame. This displacement is generated at the polarizer and its occurrence does not depend on the properties of the detection system. We give explicit results for this novel type of geometric SHEL and show that at grazing incidence this effect amounts to a displacement of multiple wavelengths, a shift larger than the one introduced by Goos?CH?nchen and Imbert?CFedorov effects.