Permeation of Penetrants in Nanocomposites: A Test of the Theory of Composites

纳米复合材料中渗透剂的渗透：复合材料理论的检验

• 批准号: 0238979
• 负责人: Donald Paul
• 金额: $ 50万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0238979&HistoricalAwards=false
• 关键词: Permeation; Penetrants; Nanocomposites; Test; Theory

The project proposed here will have broad impact on the emerging field of polymer nanocomposites since it will determine whether current theories of composites are applicable or not for predicting performance as the size of the filler particles approach molecular dimensions. Further, this project will provide a vehicle for students at all levels to learn how to answer key questions in new technical areas, where all concepts have to be questioned, using well-structured research.As used here, the term nanocomposites refers to a polymer matrix containing well-dispersed filler particles (spheres, rods, or platelets usually comprised of an inorganic material) where at least one dimension is in the range of one to tens of nanometers. The very high surface area of these particles and small distances between them raises the question of whether the particles may influence the nature or properties of the polymer matrix by interfering with the chain conformation, segmental packing, or the force field in which these segments move. The well-developed mathematical theories for predicting performance (stiffness, permeability, etc.) of conventional composites assure the properties for each phase are the same as if the other phase were not there. We must question whether the local properties of the matrix in nanocomposites are really the same as in the bulk state. We propose to answer this key question by probing these local properties by measuring the permeability of various gas and vapor penetrants in well-prepared and characterized nanocomposites. The absolute permeability of any given penetrant will depend on the detailed morphology of the composite (i.e., the aspect ratio, volume fraction, and arrangement of these particles in the matrix). However, according to composite theory, the ratio of the permeability of one penetrant to that of another should be the same in the composite as in the pure matrix. Thus, systematic and accurate measurement of the permeation of a wide range of penetrants of varying size becomes a powerful tool for exploring the applicability of composite theory to nanocomposites, i.e., whether local properties are perturbed by tiny, high surface area nanoparticles. Further, this work will address issues related to developing nanocomposites for applications as barrier materials and as membranes for separations and for fuel cells. The nanoparticles of interest will include the aluminosilicate platelets of clays (for barrier materials), spherical particles of silica and other materials (for separation membranes), particles that conduct protons (for fuel cells,), etc. The matrices will be either crystalline or glassy polymers of varying chain stiffness and interaction with the nanoparticles. The research will identify the materials issues that determine when the matrix properties are significantly affected by the filler and when they are not.

这里提出的项目将有广泛的影响，新兴领域的聚合物纳米复合材料，因为它将确定当前的复合材料理论是否适用于预测性能的填料颗粒的大小接近分子尺寸。 此外，该项目将为各级学生提供一个工具，学习如何使用结构良好的研究来回答新技术领域的关键问题，在这些领域中，所有概念都必须受到质疑。（通常由无机材料构成的球体、棒或片晶），其中至少一个尺寸在1至数十纳米的范围内。 这些颗粒的非常高的表面积和它们之间的小距离提出了这样的问题：颗粒是否可以通过干扰链构象、链段堆积或这些链段在其中移动的力场来影响聚合物基质的性质或性质。 用于预测性能（刚度、渗透率等）的成熟数学理论传统复合材料的性能保证了每一相的性能与另一相不存在时的性能相同。 我们必须质疑纳米复合材料中基体的局部性质是否真的与体相状态相同。 我们建议通过测量各种气体和蒸汽渗透剂在精心制备和表征的纳米复合材料中的渗透性来探测这些局部性质，从而回答这个关键问题。 任何给定渗透剂的绝对渗透率将取决于复合材料的详细形态（即，这些颗粒在基质中的纵横比、体积分数和排列）。 然而，根据复合材料理论，一种渗透剂与另一种渗透剂的渗透率之比在复合材料中应与在纯基体中相同。 因此，系统和准确地测量各种不同尺寸的渗透剂的渗透成为探索复合材料理论对纳米复合材料的适用性的有力工具，即，局部性质是否被微小的、高表面积的纳米颗粒干扰。 此外，这项工作将解决与开发纳米复合材料作为阻隔材料和作为分离膜和燃料电池的应用有关的问题。 感兴趣的纳米颗粒将包括粘土的铝硅酸盐片晶（用于阻隔材料）、二氧化硅和其他材料的球形颗粒（用于分离膜）、传导质子的颗粒（用于燃料电池）等。基质将是具有不同链刚度和与纳米颗粒相互作用的结晶或玻璃状聚合物。 该研究将确定材料问题，这些问题决定了基质性能何时受到填料的显著影响，何时不受影响。