Self-assembling Polysaccharide Polyelectrolytes

化学系的分析和表面化学项目将支持弗吉尼亚理工大学的Alan Esker教授和Maren Roman教授以及德国耶拿大学的Thomas Heinze教授的合作研究项目。该奖项与德国研究协会（DFG）通过国家科学基金会和DFG之间的联合计划资助的合作奖相协调，该计划共同资助美国和德国研究人员之间的合作项目。木材是一种复杂的复合材料，由三种主要成分组成：纤维素、半纤维素和木质素。这三种材料都是聚合物，大分子由相似化学结构的多个单元组成。此外，纤维素和半纤维素是具有糖亚基的多糖，而木质素具有非常不同的化学结构。尽管纤维素和木质素倾向于像油和水一样形成独立的相，但木材的一些材料性能优于纤维素和人造塑料的复合材料。半纤维素通过迁移到纤维素和木质素之间的界面（自组装），并在树木细胞壁形成过程中有效地将它们“粘合”在一起，从而有助于木材的优越性能。埃斯克和罗马小组与海因策小组之间的合作研究将集中在模仿自然以创造新的生物材料上。Heinze小组将制备具有半纤维素和木质素特性的新分子，而Esker和Roman小组将制备纤维素纳米晶体，即大约20纳米厚（比人类头发细1000倍）、数百纳米长的纤维素纤维。这些组成部分是含有多种电荷的聚电解质。因此，它们将使研究人员能够利用“异性相吸”的原理，用带相反电荷的积木在水中创造复杂的结构。一旦结构形成，研究人员将使用化学反应将结构锁定到位，并研究所得到的复合材料的机械和表面特性。这些复合材料将为设计更好的膜、传感器、医疗材料和纸浆和纸制品添加剂提供深入的见解。该项目将为学生在一个高度跨学科的领域提供良好的培训机会。它将包括在德国的美国学生和在美国的德国学生的国际研究经验。该奖项由美国国家科学基金会国际科学与工程办公室共同资助。

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.