Fracture in Nanostructured Polymeric Materials

技术概述：这项研究计划将探索嵌段共聚物的分子结构与所得到的纳米结构塑料的机械性能之间的联系。多嵌段共聚物的合成将使用可控聚合技术，并辅之以化学修饰，如催化氢化。这些化合物将以未稀释和混合的形式进行研究。自组装成有序和无序的微相分离材料将通过一系列实验技术来表征，如小角X射线和中子散射、电子显微镜、动态力学光谱和双折射分析。拉伸和冲击机械性能将被评估，并与形态结构和分子结构相关联。选定的嵌段共聚物和共混样品将通过化学蚀刻或选择性溶剂提取部分作废，从而生成纳米孔整体，并进行断裂分析。将开发新的策略来增韧这些本质上脆弱的多孔化合物，通过组合多嵌段共聚物设计，在基质材料中战略性地放置橡胶、玻璃和半结晶块，以及将多嵌段共聚物与协同分子体系混合。非技术摘要：也许没有其他类别的材料特性比机械坚固性对塑料的利用有更大的影响。这项研究计划将探索通过受控合成化学方法产生的聚合物分子结构与所产生的材料的断裂行为之间的联系。这项工作将影响新塑料在重要商业产品中的应用，包括笔记本电脑屏幕等光学介质、可能用于燃料电池和电池的新型膜，以及在汽车行业广泛使用的廉价和轻质塑料。这一计划提供了极好的机会，通过大学、当地学校和地区博物馆的互动计划，激励和告知各级科学和工程教育的学生。

TECHNICAL SUMMARY:This research program will explore the connections between the molecular architecture of block copolymers and the mechanical properties of the resulting nanostructured plastics. Mutiblock copolymers will be synthesized using controlled polymerization techniques augmented by chemical modification such as catalytic hydrogenation. These compounds will be investigated in undiluted and blended forms. Self-assembly into ordered and disordered microphase separated materials will be characterized by a compliment of experimental techniques such as small-angle X-ray and neutron scattering, electron microscopy, dynamic mechanical spectroscopy, and birefringence analysis. Tensile and impact mechanical properties will be evaluated and correlated with the morphological structure and molecular architecture. Selected block copolymer and blend specimens will be partially voided by chemical etching or selective solvent extraction resulting in nanoporous monoliths that will be subjected to fracture analysis. New strategies will be developed to toughen these intrinsically fragile porous compounds, through a combination of multiblock copolymer design, strategic placement of rubbery, glassy, and semicrystalline blocks within the matrix material, and blending of multiblock copolymers with synergistic molecular architectures.NON-TECHNICAL SUMMARY:Perhaps no other class of material properties has a greater impact on the utilization of plastics than mechanical robustness. This research program will explore the connections between the molecular structure of polymer molecules, produced by controlled synthetic chemistry methods, and the fracture behavior of the resulting materials. This work will impact the application of new plastics in commercially important products ranging from optical media such as laptop computer screen, new types of membranes that may find uses in fuel cells and batteries, and inexpensive and light plastics used extensively in the automotive industry. This program affords outstanding opportunities to enthuse and inform students at all levels of education in science and engineering through interactive programs at the University, local schools, and regional museums.