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IRTG / Soft Matter Science
Freiburger Materialforschungszentrum
Stefan-Meier-Str. 21
79104 Freiburg, Germany

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You are here: Home Events Dr. Andreas Walther "Self-assembled bioinspired materials"

Dr. Andreas Walther "Self-assembled bioinspired materials"

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Institute for Interactive Materials Research – DWI at RWTH Aachen University

  • Seminar
When Jun 05, 2014
from 10:00 AM to 10:45 AM
Where Seminarraum A, FMF, Stefan-Meier-Str. 21, Freiburg
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Nature provides prime examples of lightweight, strong, stiff and yet tough materials. Their unique properties are realized via the slow growth of hard (inorganic, protein crystals, crystalline polysaccharides) and soft (organic, biopolymeric) building blocks. Nacre, wood or silk are paradigms in materials design and considered near perfect marriages of hard and soft components. I will present on the one hand large-scale approaches for the biomimicry of mother of pearl with synthetic components, and secondly demonstrate how to utilize remarkably strong natural nanofibrils (nano-/microfibrillated cellulose + nanofibrillated chitin) to create robust and functional materials from renewable resources.

We use a self-assembly approach based on polymer-coated inorganic clay platelets with intrinsic hard/soft character to fabricate large-scale nacre-mimetic composites films and coatings with highly defined and tuneable mesostructure. This has so far enabled high modulus (45 GPa) and high strength (350 MPa) combined with low density. We will show how humidity influences the dynamic properties of the nanoconfined polymer layers and how this translates into macroscopic material properties. In terms of tuning the  mechanical properties, we will also discuss the influence of the thickness of the organic layers, the clay platelets dimensions, as well as supramolecular crosslinking to reach synergetic mechanical properties based on sacrificial bonds. As functional benefits, the resulting materials also display very low gas permeability, high transparency and astonishing fire/heat shielding capabilities. The achieved control allows generating such high-performance biomimetic composites with energy-efficient and environmentally friendly methods on a large scale, even suitable for continuous roll-to-roll processes.

Natural polysaccharide nanofibrils hold great promise for sustainable and strong materials owing to the high stiffness and high strength of the underlying, native polysaccharide crystals. I will discuss preparation of these nanofibrils and their water-borne processing into functional bioinspired high-performance composites, macroscopic fibers, and macroporous ordered hydrogel scaffolds suitable for cell culturing.

Selected References:

Nacre: (1) Das, P.; Walther, A. Nanoscale, 5, 9348 (2013). (2) Das, P.; Schipmann S.; Malho, J.-M.; Zhu, B.; Klemradt, U.; Walther, A. ACS Appl. Mater. Interfac. 5, 3738 (2013). (3) Verho, T.; Karesoja, M.; Das, P.; Martikainen, L.; Lund, R.; Alegria, A.; Walther, A.; Ikkala, O. Adv. Mater. DOI. 10.1002/adma.201301881 (2013). (4) Walther, A.; Bjurhager, I.; Malho, J.-M.; Ruokolainen, J.; Berglund, L.A.; Ikkala, O.: Angew. Chem. Int. Ed., 49, 6448 (2010) (5) Walther, A.; Bjurhager, I.; Malho, J.-M.; Pere, J.; Ruokolainen, J.; Berglund, L.A.; Ikkala, O.: Nano Letters, 10, 2742 (2010).

Nanocellulose/-chitin: (1) Benitez A. J.; Torres-Rendon, J.; Poutanen, M.; Walther, A. Biomacromolecules, 10.1021/bm401451m (2013).; (2) Das, P.; Heuser, T.; Wolf, A.; Zhu, B.; Demco, D; Ifuku, S.; Walther, A., Biomacromolecules, 13, 4205 (2012). (3) Laaksonen, P.; Walther, A.; Malho, J.-M.; Kainlauri, M.; Ikkala, O.; Linder, M. B.:, Angew. Chem. Int. Ed. 50, 8688 (2011). (4) Walther, A.; Timonen, J.V.I.; Diez, I.; Laukkaanen, A.; Ikkala, O.: Adv. Mater. 23, 2924 (2011). (5) Wang, M.; Olszewska, A.; Walther, A.; Malho, J.-M.; Schacher, F. H.; Ruokolainen, J.; Ankerfors, M.; Laine, J.; Berglund, L. A.; Osterberg, M.; Ikkala, O.: Biomacromolecules, 12, 2074 (2011)

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