Multi-scale Phenomena in Macromolecular Fluids and Nano-Composite Materials

高分子流体和纳米复合材料的多尺度现象

• 批准号: 0308019
• 负责人: M Forest
• 金额: $ 16.7万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0308019&HistoricalAwards=false
• 关键词: Multi; scale; Phenomena; Macromolecular; Fluids

The goal of this research is the development of a mathematicaltheory, models, and computational tools which underpin the design andof macromolecular materials and nano-composites. These materials arecomprised of anisotropic molecules (nematic polymers), which undergo aspontaneous disorder-order transition above a critical concentration.Materials made from nematic polymers achieve their properties throughthe collective molecular alignment structure. Specific molecularelements yield diverse property enhancements, from strength (theDupont product Kevlar and spider silk), to electrical conductivity(carbon tubes and conducting polymers), to barrier penetrationproperties (discotic clay platelets). The major technologicalchallenge is to extend results with fibers to other geometries such asfilms and molds. However, in typical laminar processing flows, themolecular response is highly sensitive to flow type and strength, andto molecular properties such as shape and concentration. In additionto complex dynamics, during flow processing there is a spatialconflict between interior flow response and molecular anchoringconditions at solid boundaries. The result is that instead of auniform molecular orientational distribution, as in fiber processingflows, film and mold flows always generate morphology on length scalesbetween the molecules and the processing devices. These ubiquitousstructures are not understood, either theoretically or experimentally,yet they dictate the effective properties of the end-use materials.The research supported by this award will help to understand the dynamicsand structures that occur in typical laminar flows of nematicpolymers.Modern high-performance materials and nano-composites are primarilydesigned with simple elements, from rod-like to platelet molecules.Remarkable property enhancements have been achieved thus far inlaboratory-scale experiments, with increased strength and durability,the ability to shield heat or gases, and to tune electromagnetic wavetransmission. The technological challenge is to scale theseexperimental results to industrially viable processes and materials.The challenge to mathematics and computational science is to build asolid foundation of theory, modeling, and simulation tools from whichto design and control the processes and final material properties.The theory of flowing molecules in confined spaces is still unable topredict and control the molecular structure created during flowprocessing. Yet micron-scale molecular structures always occur inprocessed films and molds of nano-composites. Furthermore, the bulkmaterial performance properties as well as their failure and damagemodes are dominated by the molecular structures generated inprocessing. The award will support a research program combiningtheory, modeling, simulations, and comparisons with laboratory data inthe dynamics and structure properties of nematic polymer materials andnano-composites in processing flows. These results will be the basis for the next phase of the materials pipeline, where bulk materialproperties are deduced from the molecule properties.

这项研究的目标是发展一个理论，模型和计算工具，支持设计和高分子材料和纳米复合材料。 这些材料是由各向异性的分子（聚合物）组成的，它们在超过临界浓度时会发生自发的无序-有序转变，由聚合物制成的材料通过集体的分子排列结构来实现它们的性能。 特定的分子元素产生不同的性能增强，从强度（杜邦产品凯夫拉和蜘蛛丝），导电性（碳管和 导电聚合物），阻隔渗透性能（分散性 粘土片晶）。 的 主要的技术挑战是将纤维的结果扩展到其他几何形状，如薄膜和模具。 然而，在典型的层流处理流中，分子响应对流的类型和强度以及分子特性（如形状和浓度）高度敏感。 在流动过程中，除了复杂的动力学过程外，还存在着内部流动响应与固体边界处分子锚定条件之间的空间冲突。 其结果是，而不是一个均匀的分子取向分布，如在纤维加工流程，薄膜和模具流总是产生分子和加工设备之间的长度尺度上的形态。 这些普遍存在的结构无论是理论上还是实验上都没有被理解，但它们决定了最终用途材料的有效性能。该奖项支持的研究将有助于理解向列型聚合物典型层流中发生的动力学和结构。现代高性能材料和纳米复合材料主要是用简单的元件设计的，从棒状分子到片状分子。迄今为止，在实验室规模的实验中已经实现了显着的性能增强，具有增加的强度和耐久性，屏蔽热量或气体的能力，以及调谐电磁波传输。 技术挑战 是 将这些实验结果应用于工业上可行的工艺和材料。数学和计算科学面临的挑战是建立坚实的理论基础、建模和仿真工具，以设计和控制工艺和最终的材料性能。在有限空间中流动分子的理论仍然无法预测和控制流动过程中产生的分子结构。 然而，微米级的分子结构总是出现在纳米复合材料的加工薄膜和模具中。 此外，散装材料的性能特性以及它们的失效和损坏模式， 由分子主导 在处理过程中产生的结构。 该奖项将支持一项研究计划，该计划将理论，建模，模拟以及与实验室数据的比较结合在一起，研究聚合物材料和纳米复合材料在加工流程中的动力学和结构特性。 这些结果将是材料管道下一阶段的基础，在该阶段，从分子性质推导出大块材料的性质。