Dynamical Coupling Between Particles and Polymers

颗粒与聚合物之间的动态耦合

• 批准号: 1309892
• 负责人: Michael Rubinstein
• 金额: $ 27万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1309892&HistoricalAwards=false
• 关键词: Dynamical; Coupling; Between; Particles; Polymers

TECHNICAL SUMMARYThis award supports theoretical and computational research on the motion of nanoparticles in a polymer matrix. The mean square displacement of microscopic particles larger than polymer chains provides information about rheological properties of the surrounding matrix. However, structure and dynamics of complex polymeric materials on sub-molecular length scales as well as microscopic details of polymer-particle interactions are poorly understood. The PI will analyze the motion of nanoparticles smaller than the surrounding polymer chains. Particularly interesting is the coupling of the nanoparticle dynamics to dynamical modes of matrix polymer chains on length scales equal to or smaller than the particle size and to modes of chains adsorbed or grafted to the particle.A theory of the dynamical coupling between nanoparticles and a polymer matrix will be systematically developed starting from a model of non-sticky particles freely diffusing in polymer networks and gels. Mobility of these trace particles is highly sensitive to the relation between their dimensions and the diameter of the confining tube of the entangled matrix chains. Upon uniaxial and biaxial deformation of polymer networks and gels, the corresponding change of the tube diameter causes anisotropic diffusion of tracer nanoparticles. A method for characterization of the non-affine deformation of the confining tube by measuring the anisotropy of nanoparticle mobility will be developed and tested by computer simulations. The developed models will also enable quantitative analysis of translational and rotational diffusion of non-spherical nanoparticles, such as nanorods with diameter smaller than the mesh size of polymer gels and length longer than this mesh size.The model will be extended to the case of sticky nanoparticles that exhibit hindered diffusion through polymeric liquids or solids due to chains attached to these particles. The time dependence of the mean square displacement of the sticky particles will reflect both dynamics of attached chains as well as of the surrounding polymer matrix. The proposed theory will allow separation of both contributions and determination of the structure and dynamics of the polymer layer adsorbed on nanoparticles. This theory will be modified to treat the finite lifetime of the bonds between particles and adsorbed polymers and the lifetime of labile bonds in reversible networks.The theory of mobility of sticky particles will be extended to treat heterogeneous medium with a distribution of local sticky regions using an activated hopping model. A general solution of this model will be obtained to allow the derivation of the distribution of attraction strengths of different sticky regions from the analysis of particle trajectories.This project will provide training opportunities for undergraduate and graduate students as well as postdoctoral fellows in analytical and numerical techniques for soft materials. Some of the results of this research will be used in the development of new problem sets and supplementary materials for the PIs textbook "Polymer Physics." The project will also be used as a tool for engage the interest of high school students in modern scientific methods by engaging them in active research.NONTECHNICAL SUMMARYThis award supports theoretical and computational research to study nanoparticles, particles some 100,000 times smaller than the diameter of a human hair, moving within a material made up of a tangle of long chain-like molecules called polymers. Understanding the mechanisms by which the nanoparticles move provides useful information about the properties of materials made of polymers. The PI will develop a theory that can handle nanoparticles of different sized and shape, as well as kind, including nanoparticles with smooth surfaces and nanoparticles that have polymers attached to them which tend to make them "sticky" as they interact with the polymers that make up the material. This research will has impact on technological applications, such as optimizing composite materials and designing nanoparticles for drug delivery applications. This project will provide training opportunities for undergraduate and graduate students as well as postdoctoral fellows in analytical and numerical techniques for soft materials. Some of the results of this research will be used in the development of new problem sets and supplementary materials for the PI's textbook "Polymer Physics." The project will also be used as a tool for engage the interest of high school students in modern scientific methods by engaging them in active research.

该奖项支持对聚合物基质中纳米颗粒运动的理论和计算研究。 大于聚合物链的微观颗粒的均方位移提供了关于周围基质的流变性质的信息。然而，在亚分子尺度上的复杂聚合物材料的结构和动力学以及聚合物-颗粒相互作用的微观细节知之甚少。PI将分析小于周围聚合物链的纳米颗粒的运动。特别有趣的是纳米粒子的动力学耦合到矩阵的动力学模式的聚合物链的长度尺度等于或小于颗粒尺寸和模式的链吸附或接枝到粒子。纳米粒子和聚合物基体之间的动力学耦合的理论将系统地发展从一个模型的非粘性颗粒自由扩散的聚合物网络和凝胶。这些微量粒子的流动性是高度敏感的尺寸和纠缠矩阵链的限制管的直径之间的关系。在聚合物网络和凝胶的单轴和双轴变形时，管直径的相应变化引起示踪剂纳米颗粒的各向异性扩散。将开发一种通过测量纳米颗粒迁移率的各向异性来表征约束管的非仿射变形的方法，并通过计算机模拟进行测试。所开发的模型也将使平移和旋转扩散的非球形纳米粒子，如纳米棒的直径小于聚合物凝胶的网格尺寸和长度比这个网格尺寸的定量分析。该模型将被扩展到粘性纳米粒子的情况下，表现出阻碍通过聚合物液体或固体扩散由于链连接到这些粒子。粘性颗粒的均方位移的时间依赖性将反映附着链以及周围聚合物基质的动力学。所提出的理论将允许分离的贡献和确定的结构和动力学的聚合物层吸附在纳米粒子上。本文对粘性颗粒迁移率理论进行了修正，使之适用于颗粒与吸附聚合物之间的有限键寿命和可逆网络中的不稳定键寿命，并将粘性颗粒迁移率理论推广到具有局部粘性区域分布的非均匀介质中，采用活化跳跃模型。该模型将得到一个一般的解决方案，使不同的粘性区域的吸引力强度的分布，从粒子轨迹的分析derived.This项目将提供培训机会，本科生和研究生以及博士后研究员在分析和数值技术的软材料。本研究的部分成果将被用于开发新的问题集和补充材料的PI教科书“高分子物理”。“该项目还将作为一种工具，通过让高中生积极参与研究，激发他们对现代科学方法的兴趣。非技术性总结该奖项支持对纳米颗粒的理论和计算研究，纳米颗粒比人类头发直径小10万倍，在由长链状分子组成的材料中运动，称为聚合物。了解纳米颗粒移动的机制可以提供有关聚合物材料特性的有用信息。PI将开发一种理论，可以处理不同大小和形状的纳米颗粒，以及种类，包括具有光滑表面的纳米颗粒和具有附着在其上的聚合物的纳米颗粒，这些聚合物往往使它们在与构成材料的聚合物相互作用时具有“粘性”。这项研究将对技术应用产生影响，例如优化复合材料和设计用于药物递送应用的纳米颗粒。 该项目将为本科生和研究生以及博士后研究员提供软材料分析和数值技术的培训机会。本研究的部分成果将用于PI教科书“高分子物理”的新问题集和补充材料的开发。“该项目还将作为一种工具，通过让高中生积极参与研究，激发他们对现代科学方法的兴趣。