Structure and Dynamics of Polymeric Complex Fluids

聚合物复杂流体的结构和动力学

• 批准号: 0453856
• 负责人: Simon Mochrie
• 金额: $ 40.25万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-11-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0453856&HistoricalAwards=false
• 关键词: Structure; Dynamics; Polymeric; Complex; Fluids

*******NON-TECHNICAL ABSTRACT******* Amphiphiles are molecules with end groups that exhibit very different affinities, and can organize immiscible fluids into so-called complex fluid phases with characteristic structures in the 10-100~nm range. They have applications in such diverse areas as enhanced oil recovery, living cells, and food science. This research project will characterize the behavior of polymer-based complex fluids with the goal of rigorously testing and refining theoretical understanding of these phases. This, in turn, will lead to improvements in our understanding of how to make best use of existing amphiphiles and how to design better ones for practical applications. Beyond the time-averaged behavior, thermal fluctuations in these materials will be characterized using the emerging technique of x-ray photon correlation spectroscopy (XPCS). These studies will elucidate how the fluctuations depend on the structures and properties of the phases in question, and how these properties in turn may be inferred from the observed fluctuations. Overall, the proposed experiments will create new knowledge concerning the statistical physics of amphiphilic complex fluids. Methodologies developed during the research will enable scientists from across the country to better pursue their own XPCS experiments. In addition, because the promise of XPCS measurements probing shorter length scales and shorter time scales is an important component of the rationale for new, fourth-generation, x-ray sources, including LCLS at Stanford, the ERL at Cornell, and NSLS-II at Brookhaven, this research will better inform programmatic and technical decisions concerning such facilities. Finally, it will contribute to the education and training of the next generation of scattering scientists, so that they will prepared to do the best possible facility-based science at existing and future x-ray and neutron sources.*******TECHNICAL ABSTRACT*******Because of the applicability of self-consistent mean-field theory to polymer systems, studies of block polymer-based complex fluids offer the prospect of an essentially first-principles understanding of complex fluid structure, phase behavior, and dynamics. Building on prior work that has revealed the existence of membrane-based sponge (L3) and vesicle (L4) phases in binary block copolymer-homopolymer blends, this research will clarify several key, unresolved questions concerning the phase behavior and structure of these materials, including the importance of anharmonic contributions to the membrane bending free energy, the effect of possible length-scale-dependent renormalization of the membrane elastic constants, the role of the membrane's Gaussian curvature, and the conditions required for a continuous L3-to-L4 transition. Beyond the time-averaged behavior, the equilibrium dynamics will also be characterized using the emerging technique of x-ray photon correlation spectroscopy (XPCS), in order to elucidate how the dynamics of equilibrium fluctuations depend on the structures and properties of the phases in question, and how these properties in turn may be inferred from the observed dynamics. This research will also improve the capabilities for carrying out x-ray photon correlation spectroscopy experiments, enabling scientists from across the country to pursue their own XPCS research, and will inform decisions to be made about the next generation of national x-ray facilities. It will also contribute to the education and training of the nation's next generation of scattering scientists, so that they are capable of carrying out the best possible facility-based science at existing and future x-ray and neutron sources.

** 非技术摘要 * 两亲分子是具有端基的分子，其表现出非常不同的亲和力，并且可以将不混溶的流体组织成具有10-100 nm范围内的特征结构的所谓复杂流体相。它们在提高石油采收率、活细胞和食品科学等不同领域都有应用。该研究项目将表征聚合物基复杂流体的行为，目标是严格测试和完善对这些阶段的理论理解。反过来，这将导致我们对如何最好地利用现有两亲物以及如何设计更好的两亲物以用于实际应用的理解的提高。除了时间平均行为，这些材料中的热波动将使用新兴的X射线光子相关光谱（XPCS）技术进行表征。这些研究将阐明涨落如何依赖于所讨论的相的结构和性质，以及这些性质又如何从所观察到的涨落中推断出来。总之，所提出的实验将创造新的知识，关于两亲性复杂流体的统计物理。在研究过程中开发的方法将使来自全国各地的科学家能够更好地进行自己的XPCS实验。此外，由于XPCS测量探测更短的长度尺度和更短的时间尺度的承诺是新的第四代X射线源的基本原理的重要组成部分，包括斯坦福大学的LCLS，康奈尔大学的ERL和布鲁克海文的NSLS-II，这项研究将更好地为有关这些设施的计划和技术决策提供信息。最后，它将有助于下一代散射科学家的教育和培训，使他们能够在现有和未来的X射线和中子源上做最好的基于设施的科学。技术摘要 ** 由于自洽平均场理论对聚合物体系的适用性，嵌段聚合物基复杂流体的研究提供了对复杂流体结构、相行为和动力学的基本第一原理理解的前景。基于先前揭示二元嵌段共聚物-均聚物共混物中存在膜基海绵（L3）和囊泡（L4）相的工作，本研究将澄清有关这些材料的相行为和结构的几个关键的未解决的问题，包括非谐贡献对膜弯曲自由能的重要性，可能的长度尺度依赖重整化的膜弹性常数的影响，膜的高斯曲率的作用，以及连续的L3到L4过渡所需的条件。除了时间平均的行为，平衡动力学也将使用新兴的X射线光子相关光谱（XPCS）的技术，以阐明如何平衡波动的动力学取决于结构和性能的相的问题，以及如何这些属性反过来可以从观察到的动态推断。这项研究还将提高进行X射线光子相关光谱实验的能力，使全国各地的科学家能够进行自己的XPCS研究，并将为下一代国家X射线设施的决策提供信息。它还将有助于国家下一代散射科学家的教育和培训，使他们能够在现有和未来的X射线和中子源上进行最好的设施科学。