Materials World Network: Dynamics of Polymer Nanocomposites

聚合物纳米复合材料，即分散在聚合物基质中的纳米颗粒混合物，自20世纪90年代初问世以来，在工业和基础研究中都得到了迅速的关注。丰田中央研究中心（Kojima, 1993）提供了第一个高冲击性应用之一，他证明了添加几vol %的层状硅酸盐大大改善了尼龙6的机械性能。事实上，具有改进弹性模量、导电性、阻燃性和导热性的pnc的商业用途可以在许多经济领域找到，包括航空航天、电子和体育应用。虽然某些pnc，如聚合物-纳米粘土复合材料，似乎已经达到成熟，但人们对圆柱形纳米颗粒（如碳纳米管和金属纳米线）系统的兴趣正在增加。本研究的主要目的是利用协调的实验和理论方法，为圆柱形纳米颗粒存在下的聚合物动力学提供基本的理解。这个提议的材料世界网络包含纳米粒子合成、纳米复合材料制造、成像、深度剖面、流变学、理论和模拟方面的专业知识，系统地解决了长径比从2到500的圆柱形纳米粒子的存在如何影响聚合物动力学。这个MWN团队在聚合物纳米复合材料方面拥有丰富的经验，并致力于共同探索这些迷人且具有商业重要性的材料中的聚合物扩散和流变性。拟建的材料世界网络为聚合物纳米复合材料的物理学提供了开创性的见解，这可能对新兴的聚合物纳米复合材料产业产生积极的影响。虽然我们提出的研究将集中在两种类型的圆柱形纳米粒子，碳纳米管和金属纳米线，我们的发现将适用于广泛的圆柱形纳米粒子。在设计纳米复合材料的制造方法时，了解聚合物动力学尤为重要。当含有高浓度纳米颗粒的母料与纯聚合物熔融混合时，聚合物的扩散速度对于建立均匀浓度至关重要。例如，为了平衡碳纳米管的高成本和其吸引人的性能，一种策略是用碳纳米管涂覆乳胶颗粒，然后烧结颗粒以获得良好的界面强度。材料的强度是由聚合物在界面区域的相互扩散形成缠结决定的，这一机制将被提出的研究所启发。在更远的地方，探测细长纳米颗粒的动力学可以深入了解在活细胞拥挤的细胞内区域移动的僵硬生物分子的弛豫。

Polymer nanocomposites, namely mixtures of nanoparticles dispersed in a polymer matrix, have gained rapid attention for both industrial and fundamental studies since their introduction in the early 1990's. One of the first high impact applications was provided by Toyota Central Research (Kojima, 1993) who demonstrated that the addition of a few vol % of layered silicate greatly improved the mechanical properties of nylon 6. In fact, the commercial use of PNCs with improved elastic modulus, electrical conductivity, flame retardation and thermal conductivity can be found across many economic sectors including aerospace, electronics, and sporting applications. Whereas certain PNCs, such as polymer-nanoclay composites, appear to be reaching maturity, interest in systems with cylindrical nanoparticles, such as carbon nanotubes and metal nanowires, is increasing.The main objective of this research is to provide fundamental understanding of polymer dynamics in the presence of cylindrical nanoparticles using a coordinated experimental and theoretical approach. This proposed Materials World Network contains expertise in nanoparticle synthesis, nanocomposite fabrication, imaging, depth profiling, rheology, theory and simulation to systematically address how the presence of cylindrical nanoparticles with aspect ration from 2 to 500 impacts polymer dynamics. This MWN team has considerable experience in polymer nancomposites and is committed to working together to explore polymer diffusion and rheology in these fascinating and commercially-important materials.The proposed Materials World Network is well-positioned for groundbreaking insights into the physics of polymer nanocomposites that are likely to have positive impact on the emerging industry of polymer nanocomposites. While our proposed research will focus on two types of cylindrical nanoparticles, carbon nanotubes and metal nanowires, our findings will be applicable to a broad range of cylindrical nanoparticles. Understanding the polymer dynamics is particularly important when designing fabrication methods for nanocomposites. When a master batch containing a high concentration of nanoparticles is melt mixed with a neat polymer, the rate of polymer diffusion is critical for establishing a homogeneous concentration. For example, one strategy for balancing the high cost of CNTs with their attractive properties involves coating latex particles with CNTs and then sintering the particles to achieve good interfacial strength. The material strength is determined by the interdiffusion of polymers across the interfacial region to form entanglements and the mechanism for this will be enlightened by the proposed research. Further afield, probing the dynamics of elongated nanoparticles can provide insight into the relaxations of stiff biological molecules moving in the crowded intracellular region of living cells.