Influence of reaction conditions on the solution polymerization of vinyl acetate

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A computer-supported learning platform for pupils with cognitive disabilities

Although there is no doubt that computers are highly capable to provide pupils with cognitive disabilities in learning we observe an immense lack of professional learning software for this target group. On the one hand, there are products designed by special education teachers with a high level of instructional design. But these products are usually at a low technical level, unflexible and adapted for the special situation they are designed for. On the other hand there are loads of colourful animated commercial products, but with absence of any instructional quality. In our project we want to overcome these problems by developing a learning platform for this special target group in an interdisciplinary group based on participatory design principles

(Non-)linear spectroscopy based on classical trajectories

Die vorliegende Arbeit untersucht wie aus klassischen Trajektorien lineare und nichtlineare Spektren berechnet werden können. Die Eigenschaften der dazu notwendigen klassischen Response-Funktionen (RF), die sich durch Stabilitätsmatritzen formulieren lassen, werden an Modellsystemen untersucht. Nur in chaotischen Systemen konvergieren die RF durch aufwendiges Mitteln über Boltzmann verteilte Anfangsbedingungen. Die als Anwendung der Methode ausgesuchte C-H Streckschwingung einer Ionische Flüssigkeit wird in MM Simulationen nicht korrekt beschrieben, wie ein Vergleich mit DFT-Rechnungen zeigt

Understanding polymerization processes in detail by combining experimental and modeling studies

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Co-flow microfluidic synthesis of liquid crystalline actuating Janus particles

A microfluidic synthesis of stimuli-responsive actuating Janus particles composed of a liquid crystalline elastomer (LCE) and a polymeric hydrogel is reported. , In this article the microfluidic synthesis and characterization of micrometer sized actuating Janus particles containing a liquid crystalline elastomer (LCE) is presented. On one side these Janus particles consist of a hydrophobic liquid crystalline part, featuring strong shape changes during the thermotropic phase transition, whereas the other side contains a hydrophilic polyacrylamide network. The synthesis is based upon the dispersion of two immiscible monomer mixtures in a continuously flowing silicone oil, using two glass capillaries side by side to form Janus microdroplets of different morphologies. Furthermore, the systematic adjustment of the morphology of the Janus particles as well as the optimization of the actuation properties is conducted by precise control and variation of the microfluidic parameters. The actuation properties of the particles are studied by polarized optical microscopy (POM), in which relative length changes up to 52% are investigated for the elongation of LCEs during the phase transition in rod-like Janus particles. Further wide-angle X-ray scattering (WAXS) measurements verify the mesogen's orientation in a bipolar director field, which corresponds to the observed geometry of the Janus particle's shape changes

Stereo-selective swelling of imprinted cholesteric networks

Molecular chirality, and the chiral symmetry breaking of resulting macroscopic phases, can be topologically imprinted and manipulated by crosslinking and swelling of polymer networks. We present a new experimental approach to stereo-specific separation of chiral isomers by using a cholesteric elastomer in which a helical director distribution has been topological imprinted by crosslinking. This makes the material unusual in that is has a strong phase chirality, but no molecular chirality at all; we study the nature and parameters controlling the twist-untwist transition. Adding a racemic mixture to the imprinted network results in selective swelling by only the component of ``correct'' handedness. We investigate the capacity of demixing in a racemic environment, which depends on network parameters and the underlying nematic order

Определение эффективности нейтронного детектора из пластического сцинтиллятора o100?200 мм

Рассчитывается и экспериментально проверяется эффективность детектора. к нейтронам сверхвысоких (десятки и сотни МэВ) энергий