TY - JOUR A1 - Geyer, Marvin A1 - Leven, Felix A1 - Limberg, Johannes A1 - Andronescu, Corina A1 - Ostermann, Rainer T1 - Reproducible Superinsulation Materials: Organosilica-Based Hybrid Aerogels with Flexibility Control JF - Gels (Special Issue Aerogels: Synthesis and Applications) N2 - In this study, we report highly crosslinked hybrid aerogels with an organic backbone based on vinylmethyldimethoxysilane (VMDMS) with tuneable properties. For an improved and highly reproducible synthesis, a prepolymer based on 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (D4V4) and VMDMS as monomers was prepared and purified. Di-tert-butylperoxide (DTBP) concentrations of 1 mol% initiate the radical polymerization of the mentioned monomers to achieve high yields of polymers. After purification, the obtained viscous polyorganosilane precursor could be reproducibly crosslinked with dimethyldimethoxysilane (DMDMS) or methyltrimethoxysilane (MTMS) to form gels in benzylic alcohol (BzOH), water (H2O) and tetramethylammonium hydroxide (TMAOH). Whereas freeze-drying these silica-based hybrid aerogels led to high thermal conductivity (>20 mW m−1K−1) and very fragile materials, useful aerogels were obtained via solvent exchange and supercritical drying with CO2. The DMDMS-based aerogels exhibit enhanced compressibility (31% at 7 kPa) and low thermal conductivity (16.5 mW m−1K−1) with densities around (0.111 g cm−3). The use of MTMS results in aerogels with lower compressibility (21% at 7 kPa) and higher density (0.124 g cm−3) but excellent insulating properties (14.8 mW m−1K−1). KW - hybrid aerogel KW - supercritical drying KW - bendability/flexibility control KW - radical polymerization KW - polycondensation KW - superinsulation material KW - energy storage Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1010-opus4-47738 SN - 2310-2861 VL - 2024 IS - 10 (11) SP - 1 EP - 14 PB - MDPI ER - TY - JOUR A1 - Leven, Felix A1 - Limberg, Johannes A1 - Noll, Jessica A1 - Ulbricht, Mathias A1 - Ostermann, Rainer T1 - Enhancing the phase change material properties by an energy-efficient one-step preparation method using organogelator–polyolefin composites JF - Materials Advances N2 - The synergistic combination of various sorbitol-based organogelators with polyolefins allows the preparation of porous support structures for immobilized phase change materials (PCMs). Using a PCM as a solvent for the preparation leads to dimensionally stable composite materials with extremely high loading rates and low leakage of PCMs. Detailed investigations were performed on the kind of polyolefin support and its mass fraction concentration in the PCM, the temperature-dependent softening and failure under superimposed load, the efficiency of heat transport and the retention capacity over several melting/solidification cycles in various measurement setups. In particular, paraffin wax in combination with 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol (TBPMN) and ultrahigh molecular weight polyethylene (UHMWPE) showed the best results in terms of high dimensional stability, low leakage, excellent processability and competitive heat capacity. The herein-established one-step preparation method saves time and energy compared to the loading of pre-formed porous supports and improves application-related properties at the same time. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1010-opus4-47824 SN - 2633-5409 VL - 2022 IS - No. 3, Issue 21 SP - 7872 EP - 7880 PB - Royal Society of Chemistry ER - TY - JOUR A1 - Noll, Jessica A1 - Leven, Felix A1 - Limberg, Johannes A1 - Weidmann, Christoph A1 - Ostermann, Rainer T1 - Electrospinning as a Fascinating Platform for Teaching Applied Polymer Science with Safe and Sustainable Experiments JF - Journal of Chemical Education N2 - Abstract Electrospinning has been widely used as a versatile technique to generate nanofibers of various materials. It is also helpful in teaching topics ranging from macromolecular chemistry to physics, safety, and sustainability at various levels of difficulty and student involvement. Simple and safe hands-on experiments/manual assays can be realized for less than 30 euros to demonstrate polymer viscosity and nanofiber alignment and solubility. Students can further study (super)hydrophobicity and even upcycle packaging waste into useful filter materials but also improve the electrospinning setup from a manual assay to an inexpensive Arduino-based 3D printed research platform. Alternatively, the latter can be used for teacher demonstrations of more challenging experiments that can also be easily done using a commercial syringe-pump. KW - Electrospinning KW - Polymer KW - Nanoscience KW - Sustainability KW - First-Year Undergraduate KW - Multidisciplinary KW - Demonstrations KW - Materials Science Y1 - 2024 UR - https://pubs.acs.org/doi/10.1021/acs.jchemed.4c00504 U6 - https://doi.org/10.1021/acs.jchemed.4c00504 VL - 2024 IS - Volume 101, Issue 9 SP - 3936 EP - 3943 PB - ACS Publications ER -