emulsion; cellulose nanocrystals; 3D-printing; hierarchically-structured composites; chemical modification; mechanical properties
Hausmann Michael K., Rühs Patrick A., Siqueira Gilberto, Läuger Jörg, Libanori Rafael, Zimmermann Tanja, Studart André R. (2018), Dynamics of Cellulose Nanocrystal Alignment during 3D Printing, in ACS Nano
, 12(7), 6926-6937.
HausmannMichael, HauserAlina, SiqueiraGilberto, LibanoriRafael, VehusheiaSigne Lin, SchürleSimone, ZimmermannTanja, StudartAndré R., Cellulose-Based Microparticles for Magnetically Controlled Optical Modulation and Sensing, in Small
HausmannMichael, SiqueiraGilberto, LibanoriRafael, KokkinisDimitri, NeelsAntonia, ZimmermannTanja, StudartAndré R., Complex-Shaped Cellulose Composites Made by Wet Densification of 3D Printed Scaffolds, in Advance Functional Materials
Most natural materials are composites based on polymers and anisotropic reinforcing particles, which are often organized in a hierarchical microstructure. Hierarchical structuring is a design strategy used in biological materials to achieve unusual set of mechanical properties through the implementation of different microstructural features at multiple length scales. Another particular characteristic of biological composites is their multifunctionality. Using biologically-mediated self-assembling principles, natural systems like bone, seashells and trees have evolved their microstructural design at different levels of hierarchy to efficiently harness the load-bearing ability of their constituents and fulfill specific mechanical demands of their natural habitat.The remarkable mechanical performance exhibited by biological systems has stimulated significant amount of research in the development and fabrication of bioinspired synthetic materials with unusual combination of mechanical properties. The wide range of mechanical behavior of synthetic building blocks enables the engineer to tailor the mechanical performance of load-bearing structures simply by selecting a single component according to its mechanical response and compatibility with the fabrication process. However, translating the hierarchical features that are found in natural systems at the micro- and nano-scales to synthetic materials remains a huge challenge. The difficulties to implement such intricate hierarchical microstructure into artificial materials with conventional fabrication methods are reflected in the limited number of examples available in the literature.The goal of this research project is to develop and investigate hierarchically-structured cellulose-based composites whose microstructures resemble those of biological materials exhibiting superior mechanical performance, such as wood and bone. . The synthetic composites to be developed in this project will allow us to gain a deeper understanding over the structure-property relationships at multiple length scales in hierarchical architectures, thus providing guidelines for the fabrication of stronger, tougher and lighter composite materials. To achieve our goal, we will first extract cellulose nanocrystals with different aspect ratio (L/d) from different sources, namely wood pulp, bacterial cellulose and algae. Next, we will direct the assembly of the cellulose nanocrystals into micron-sized bundles using an emulsion-based technique. For this purpose, surface modification of cellulose nanocrystals will be performed to tailor the interaction between reinforcing elements and the interphase present in the bundles. The cellulose bundles will be magnetically modified and utilized as reinforcing elements to produce hierarchical composites with microstructures that can be tailored by applying magnetic assembly techniques and/or 3D- printing. Finally, the morphological and macromechanical properties of this new class of cellulose-composites will be assessed by standard characterization techniques such as scanning electronic microscoy (SEM), transmission electronic microscopy (TEM), quasi-static uniaxial mechanical tests and dynamic mechanical analysis (DMA). To gain insight into the cooperative deformation mechanisms at the different hierarchical levels, in-situ tensile testing will be combined with wide angle x-ray diffraction (WAXD) and small-angle x-ray scattering (SAXS) techniques in a synchrotron facility.