M. O. Pretscher, T. Chen, G. Sitaru, S. Gekle, J. Ji, S. Agarwal
Precise 2D‐patterned Incompatible Catalysts for Reactions in One‐pot, Chem., 2019.
We show precise and direct two‐dimensional (2D) printing of the incompatible polymer acid‐base catalysts and their utility in one‐pot two‐step reactions. Multi‐step catalytic reactions using incompatible catalysts in a one‐pot reaction cascade require special methods and materials for isolation of catalysts from each other. This, in general is a tedious process requiring special polymer architectures as catalysts’ carrier for preserving the activity of otherwise incompatible catalysts. We propose the immobilization of incompatible polymer catalysts, such as polymer acid and base catalysts, on a substrate in variable sizes and amounts by precise 2D printing. The copolymers with a basic (4‐vinylpyridine) and acidic (styrene sulfonic acid) functionality and methacryloyl benzophenone as a UV cross‐linking unit were used for 2D printing. The printed meshes were immersed together in a reaction solution containing (dimethoxy methyl)‐benzene and ethyl cyanoformate, resulting in a two‐step acid‐base catalyzed cascade reaction, i.e. deacetalization followed by carbon‐building reaction. The time‐dependent consumption of (dimethoxymethyl)‐benzene to the intermediate benzaldehyde and the product was monitored, and a kinetic model was developed to investigate the underlying reaction dynamics. The complexity of multi‐step Wolf‐Lamb‐type reactions was generally significantly decreased using our approach due to the easy polymerization and immobilization procedure.
New Review by S. Agarwal, S. Jiang, Y. Chen published in Macromol. Mater.
S. Agarwal, S. Jiang, Y. Chen
Macromol. Mater. Eng., 2018, 1800548
Welcome to Macromolecular Chemistry II
Spruch der Woche
Perfektion ist erreicht, nicht, wenn sich nichts mehr hinzufügen lässt, sondern, wenn man nichts mehr wegnehmen kann. (Antoine de Saint-Exupery) (Perfection is achieved, not when nothing more can be added, but when nothing more can be taken away (Antoine de Saint-Exupery))
"Die reinste Form des Wahnsinns ist es, alles beim Alten zu lassen und gleichzeitig zu hoffen, dass sich etwas ändert. (The sheerest madness is to leave everything the way it is and to simultaneously hope that something will change)" Albert Einstein
"The fate of genius is to be misunderstood, but not everything is a misunderstood genius" Ralp Waldo Emmerson (1803-1882)
"Facts do not cease to exist because they are ignored” (Aldous Huxley, author of Brave New World)
"Die Ablehnung Unwichtiges zu tun, ist eine entscheidende Voraussetzung für den Erfolg“ Sir Alexander MacKenzie
"An idea that is not dangerous is unworthy of being called an idea at all“ von Oscar Wilde (Eine Idee, die nicht gewagt ist, verdient es nicht, überhaupt eine Idee genannt zu werden)
J. Y. Cheong, L. Benker, J. Zhu, D.-Y. Youn, H. Hou, S. Agarwal, I.-D. Kim, A. Greiner
Generalized and feasible strategy to prepare ultra-porous, low density, compressible carbon nanoparticle sponges, Carbon, 2019, 363-369.
For the last two decades, nanostructured carbon materials have attracted significant attention, as they exhibit unusual physicochemical properties different from their bulk counterpart. Nevertheless, agglomeration and re-stacking of carbon nanostructures have always limited optimal performance, with larger loading amount. To solve this issue, porous and compressible carbon-based sponges have been researched, but most of the previously suggested carbon foams were either not very porous, synthesized at high temperature heat treatment, and/or not applicable for carbon nanoparticles. In this work, we have successfully fabricated ultra-porous (porosity about 98–99%), polyimide-carbon nanoparticle (PI–C) composites by combining Ketjen black nanoparticles with PI short fibers, by simple freeze-drying and subsequent heat treatments at low temperature (240 °C). Based on the analysis, it has been discovered that the fabricated PI-C sponges not only exhibit highly robust mechanical properties but also retain low thermal conductivity even in comparison with pristine PI sponges. This work provides a milestone in fabricating a number of C-electrospun polymeric sponges by freeze drying and subsequent heat treatments, which are expected to be utilized in various fields of research.