@misc{EfimovaVargaMatuscheketal., author = {Efimova, Anastasia and Varga, Janos and Matuschek, Georg and Saraji-Bozorgzad, Mohammad R. and Denner, Thomas and Zimmermann, Ralf and Schmidt, Peer}, title = {Thermal Resilience of Imidazolium-Based Ionic Liquids—Studies on Short- and Long-Term Thermal Stability and Decomposition Mechanism of 1-Alkyl-3-methylimidazolium Halides by Thermal Analysis and Single-Photon Ionization Time-of-Flight Mass Spectrometry}, series = {Journal of Physical Chemistry B}, volume = {122}, journal = {Journal of Physical Chemistry B}, number = {37}, doi = {10.1021/acs.jpcb.8b06416}, pages = {8738 -- 8749}, abstract = {Ionic liquids are often considered as green alternatives of volatile organic solvents. The thermal behavior of the ionic liquids is relevant for a number of emerging large-scale applications at elevated temperature. Knowledge about the degradation products is indispensable for treatment and recycling of the used ionic liquids. The objective of this paper was an investigation of the short- and long-term stability of several 1-alkyl-3-methylimidazolium halides, determination of the degradation products, and the elucidation of their decomposition patterns and structure-stability relations. Short-term stability and mechanism of thermal degradation were investigated by a self-developed, innovative thermal analysis single-photon ionization time-of-flight mass spectrometry device with Skimmer coupling. The applied technology provides real-time monitoring of the forming species and allows tracing their change during the course of the decomposition. Therein, the almost fragment-free soft ionization with vacuum ultraviolet photons plays a crucial role. We have detected unfragmented molecules whose formation was only assumed by electron ionization. Nevertheless, the main decomposition products of the selected ionic liquids were alkyl imidazoles, alkenes, alkyl halides, and hydrogen halides. From the decomposition products, we have deduced the fragmentation patterns and discussed their interrelation with the length of the alkyl chain and the type of the halide anion. Our results did not suggest the evaporation of the investigated ionic liquids prior to their decomposition under atmospheric conditions. Long-term thermal stability and applicability were determined based on thermogravimetric analysis evaluated with a kinetic model. Thus, the time-dependent maximum operation temperature (MOT) for the respective ionic liquids has been calculated. As a rule, the short-term stability overestimates the long-term decomposition temperatures; the calculated MOT are significantly lower (at least 100 K) than the standardly obtained decomposition temperatures.}, language = {en} } @misc{BoehlerRosencrantzWolfetal., author = {B{\"o}hler, Stefan and Rosencrantz, Sophia and Wolf, Karina and Heinemann, Robert and Schmidt, Peer and Ganster, Johannes and B{\"u}sse, Thomas and Balko, Jens and Rosencrantz, Ruben R.}, title = {Active protease formulation in commodity polymers withstands melt processing into compounds and blown films}, series = {Materials Today Communications}, volume = {34}, journal = {Materials Today Communications}, issn = {2352-4928}, doi = {10.1016/j.mtcomm.2022.105018}, pages = {1 -- 9}, abstract = {Integrating enzymes into thermoplastic polymers is challenging due to their lack of robustness with respect to temperature and shear fields during conventional melt processing. In the present study, blown films from low-density polyethylene (LDPE) were prepared containing a technical protease from Bacillus sp. First, LDPE/protease compounds were produced followed by blown film extrusion, both processes at melt mass temperatures of 130 °C or higher. Enzyme activity was proven, both for the LDPE/protease compound and the blown film. The highest enzyme activity in the compound was determined for processing at 132 °C and a screw speed of 75 rpm. The influence of melt temperature and shear fields was studied in detail. Enzyme activities were determined for melt temperatures up to 160 °C and for screw speeds ranging from 75 to 300 rpm during compounding by twin-screw extrusion. The process was also applied for biobased and biodegradable polyesters, where similar protease activity after compounding was verified. Electron microscopy, X-ray diffraction, nuclear magnetic resonance spectroscopy and differential scanning calorimetry served to analyze components and morphology of the enzyme formulation used here. It is proposed that the porous morphology of the protease particles is beneficial for the enzyme to remain active after processing. Additionally, the polymer matrix surrounding the particles protects the protease at elevated temperatures, which can be attributed to thermal insulation. Thus, the right combination of a suited technical enzyme formulation with appropriate mild melt compounding conditions allows enzymes to be incorporated into thermoplastics and retain their activity. This opens the way to use the abundant biological functions of enzymes in thermoplastic applications.}, language = {en} }