New Publication:Breaking Barriers in Ion Conductivity
We are proud to highlight another publication by Prof. Dr. Oliver Weichold. Together with Pia B. Sassmann, he co-authored the study Synergistic effects in cross-linked blends of ion-conducting PEO-/PPO-based unsaturated polyesters, which presents an innovative approach to enhancing ion conductivity.
In this work, unsaturated polyesters (UP) based on poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) were synthesized, doped with lithium perchlorate (LiClO₄), and cross-linked with styrene using a redox initiator. The findings reveal distinct behaviors in conductivity between PEO- and PPO-based polyester networks. While the conductivity decreases with increasing molecular weight for PEO, the opposite trend is observed for PPO.
Remarkably, the study discovered that targeted blending and cross-linking of PEO- and PPO-based polyesters can create synergistic effects. A 1:1 blend of short-chain PPO and long-chain PEO exhibited a resistivity five times lower than pure PEO and three times lower than pure PPO. These effects are attributed to enhanced chain mobility and intrachain hopping mechanisms, which are amplified by the cross-linking process.
Beyond improved ion conductivity, these networks offer rubber-like elasticity and high water tolerance, making them suitable for diverse applications, particularly under mechanical stress, in atmospheric conditions, or even in aqueous environments where standard ion-conducting systems often fail.
Sassmann, P.B., Weichold, O.
Synergistic effects in cross-linked blends of ion-conducting PEO-/PPO-based unsaturated polyesters
Ionics 27, 3857–3867 (2021). https://doi.org/10.1007/s11581-021-04149-z
Book chapter
Eine sehr grundlegende Einführung in das Thema Polymerchemie findet sich in
O. Weichold, Introduction to Polymer Chemistry. In: P. Richet, R. Conradt, A. Takada, J. Dyon (Hrsg.) Encyclopedia of Glass Science, Technology, History, and Culture Vol. 2. Wiley-VCH, New York, 2021, S. 1043–1055. https://doi.org/10.1002/9781118801017
Poster
Tim Mrohs presented a poster entitled: ‘Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete’ at the 3rd International Conference on the Chemistry of Construction Materials (ICCCM) 2021 of the GDCh Bauchemie, which took place online.
Cutting Edge Tech for Cutting-Edge Materials
We have put a Stepcraft M.1000 CNC milling machine into operation in order to produce test specimens and samples from our bio-based materials in a reproducible and high-quality manner. With a generous working area of 679 × 1044 mm², it enables the precise machining of a wide range of materials and opens up new possibilities for our research projects.
Thanks to the CNC milling machine, we can precisely realise complex geometries and individual designs – an important step towards comprehensively testing the performance and applicability of our bio-based materials.
New project:Recycled foams
A project for the development of mechanically stable foams was approved retroactively to 1 November. The project builds on the materials described in Appl. Sci. 2020 described materials. In addition, the effect of fillers made from recycled materials will be tested. The project is supervised by Fabian Weitenhagen.
(Deutsch) Neue Veröffentlichung:
Federn als Bindemittel und Flammschutz
The increasing demand for sustainable building materials requires alternative flame retardants that are more sustainable than those used to date. In this context, we present our first results with recycled poultry feather waste for the production of flame-retardant fibreboards. Impregnated wood fibres show a significantly reduced decomposition rate and decomposition temperatures that are approx. 50 °C higher. In addition, decomposition takes place gradually and not immediately as with untreated wood. With a total protein content of approx. 10 % by weight, the boards produced using the wet process are self-extinguishing and do not smoulder. In the three-point bending test, these fibreboards failed at 15 N/mm2, the limit value required by DIN EN 622 for commercially available, formaldehyde-bonded MBH fibreboards. This shows that the recycled feather residues not only have an impressive flame-retardant effect, but can also be used as a fully-fledged binder for a new generation of ecological fibreboards. As these boards are based exclusively on natural materials, they can be shredded and composted at the end of their life cycle.
The article was selected by the Journal for the cover of issue 5(50).
M. Brenner, O. Weichold
Protein Hydrolysates from Biogenic Waste as an Ecological Flame Retarder and Binder for Fiberboards
ACS Omega 2020, 5, 32227−32233. https://dx.doi.org/10.1021/acsomega.0c03819
Spray and Yay!
The Büchi S-290 mini spray dryer can be used to produce powders with a defined particle size from aqueous or organic solutions and dispersions. The efficiency and reproducibility of the S-290 offer the working group the opportunity to advance basic research and application-orientated projects in equal measure.
New PhD Student
Fabian Weitenhagen joined our team in the field of bio-based building materials in December. He is continuing his research into bio-based polycondensation resins and is building on the results of previous work. He is also developing innovative bio-based composites to promote sustainable solutions for the construction industry.
New PhD Student
In April, we welcomed Tim Mrohs to the gels department. As part of his dissertation, he is researching hydrogels based on highly alkaline diallyldimethylammonium hydroxide (DADMAOH) for use in building preservation. He is focussing in particular on the development of alkali-stable crosslinkers and the formulation and investigation of molecular gel network structures. We wish him every success in his research and welcome him to the working group.
New publication:
Duroplasts with a difference
Nature avoids highly reactive functional groups, such as isocyanate and epoxy, by using highly specialised enzymes as catalysts in condensation reactions. Consequently, bio-based raw materials require in vitro reaction conditions that are often difficult to reconcile with the requirements for thermoset resins. In addition, condensation reactions release small molecules (often water), which leads to the formation of foams under standard reaction conditions. It would therefore appear that natural building blocks would not be suitable for the production of thermosetting resins.
We show here that the addition of chopped feathers prevents the previously reported foaming of highly cross-linked combinations such as citric acid/glycerol, increases conversion and improves flame retardant properties.
M. Brenner, C. Popescu, O. Weichold
Anti-Frothing E ffect of Poultry Feathers in Bio-Based, Polycondensation-Type Thermoset Composites
Appl. Sci. 2020, 10, 2150; https://doi:10.3390/app10062150
