Self-assembling Polysaccharide Polyelectrolytes

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

The Analytical and Surface Chemistry Program in the Division of Chemistry will support the collaborative research program of Prof. Alan Esker and Prof. Maren Roman of Virginia Tech University and Prof. Thomas Heinze of the University of Jena, Germany. This award coordinates with a collaborative award funded by the Deutsche Forschungsgemeinschaft (DFG) through a joint program between the NSF and DFG that jointly funds collaborative projects between US and German investigators. Wood represents a complex composite material comprised of three principle components: cellulose, hemicelluloses, and lignin. All three of these materials are polymers, large molecules made up of multiple units of similar chemical structure. Furthermore, cellulose and hemicelluloses are polysaccharides with sugar subunits, whereas lignin has a very different chemical structure. Even though cellulose and lignin prefer to form separate phases, like oil and water, wood has some material properties that are superior to composites of cellulose and manmade plastics. Hemicelluloses contribute to wood's superior properties by migrating to the interface between cellulose and lignin (self-assembly) and effectively "glue" them together during the formation of the tree's cell wall. The collaborative studies between the Esker and Roman groups and the Heinze group will focus on trying to mimic nature to create new biomaterials. The Heinze group will prepare new molecules that have properties of both hemicelluloses and lignin, while the Esker and Roman groups will prepare cellulose nanocrystals, cellulose fibers that are about ~20 nanometers thick (~1000 times thinner than a human hair) and several hundred nanometers long. These building blocks are polyelectrolytes, which contain multiple charges. Therefore, they will enable the researchers to use the principle that "opposites attract" to create complex structures in water from oppositely charged building blocks. Once the structures are formed, the researchers will use chemical reactions to lock the structures in place and study the mechanical and surface properties of the resulting composite materials. These composites should provide deep insight into the design of better membranes, sensors, medical materials, and additives for pulp and paper products. The project will provide excellent training opportunities to students in a highly multi-disciplinary area. It will will include international research experience for US students in Germany and for German students in the US. The award is co-funded by the Office of International Science and Engineering at NSF.