uni'wissen 02(4)-2011_ENG

sources. Thanks to the million euros in prize money and additional backing from the Univer- sity of Freiburg, Samyn now has enough funding to support a research group for the coming five years. His research involves chemistry, physics, engineering, materials science, and other neigh- boring fields. It is still quiet in his laboratory. The shiny new spectrometer and the few other appa- ratuses smell like they just came out of the box; the beakers and other research implements haven’t even been touched yet. Samyn is still looking for collaborators for his group – such as a doctoral candidate from one of the contributing disciplines. “The junior professorship is an incredible op- portunity for me to conduct my own research and plan for the long term,” says Samyn with a gleam in his eye, only to warn immediately afterwards against excessive expectations. He will have to begin from square one, as it were: “Materials re- search is a new field of work for us.” Traditionally, FOBAWI has been active in the area of wood quality and logistics, the path from the forest to wood. The institute has only been working with new materials in the past two years, he explains: “For us it is an opportunity to gain control over the entire process chain, from the tree to the fi- nal product.” However, Samyn estimates that it will be three to four years before he develops a reliable method for coating paper, cardboard, or certain textiles with biopolymers combined with wood-based nanoparticles – and even then only on a laboratory scale, where he can apply the fluid coatings to the materials with relative ease. In industrial papermaking, on the other hand, 1500 meters of paper per minute roll off the pro- duction line. “That requires completely different application techniques,” explains Samyn. “In or- der to close the gap between the lab and the fac- tory we will need to acquire detailed knowledge of the flow behavior of new biomaterials.” Less Material, Better Properties The subject of Samyn’s research is complex – and so are his materials. The manufacturing in- dustry needs pulp for cotton, diapers, compress- es, and paper. For each ton of pulp, a ton of black liquor and around ten kilograms of cellu- lose with shorter fibers are created as byprod- ucts. “These fibers can be broken down chemi- cally and used to produce further materials,” says Samyn. In order to achieve this, he is coop- erating with a neighboring research group led by his colleague Prof. Dr. Marie-Pierre Laborie. The chemical processing leads to shorter cellulose nanoparticles. These so-called “whiskers” are between 100 and 200 nanometers long. The cel- lulose chains of the whiskers are arranged in a very regular pattern, almost like in a crystal structure. The reactive groups of the chain are placed such that they easily enter into reactions with other materials. It is therefore possible to mix these nanoparticles with other materials to create a composite material. “But unfortunately the cellulose particles also tend to clump togeth- er and are thus often not arranged very nicely,” says Samyn, who is working on a way to improve the arrangement of the materials. Samyn is trying to solve this problem by con- trolling the surface properties of the whiskers. In order to do this, he combines the cellulose par- ticles with a second type of nanoparticle based on vegetable oil. “I have a lot of experience with these particles,” he says. Besides, they exhibit very good properties in paper coatings. The par- ticles are already produced, but the combination with biologically based materials from agricultur- al products is new. The nanoparticles are inte- grated into a composite matrix of these biopoly- mers. A technique of this kind is already being used for simple applications. For instance, lactic acid polymers – so-called polylactides – can be Surface comparison: This microscopic image shows packaging paper with uncoated (lower half) and coated cellulose fibers. “For us it is an opportunity to gain control over the entire process chain, from the tree to the final product” 26