CAREER: Dynamics, Rheology, and Microrheology of Rigid Polymers and Brownian Fibers

摘要CTS-0348205J。该研究计划的总体目标是阐明布朗棒悬浮液的动力学和流变学，同时开发微观流变学作为表征含有刚性布朗颗粒的复杂流体的工具。提高刚性聚合物和布朗纤维材料的性能和创造新的应用，在一定程度上取决于对其物理性质的准确测定。为了表征Ridgid聚合物和布朗纤维，材料科学家和工程师测量了颗粒扩散系数和流体流变性等参数。对结果的解释依赖于理论，这些理论通常提供定性的比例定律，而不是定量的预测。为了消除定量预测和测量之间的差距，正在进行一项实验和计算研究相结合的计划。该实验程序使用微观流变学来评估各向同性布朗杆悬浮液的线性粘弹性响应，并测量剪切流排列的布朗杆悬浮液的粘度。在相同的悬浮液上，将直接与标准剪切流变学的测量结果进行比较。将使用流变学和微观流变学的模拟来解释测量结果。这些模拟将是第一次对布朗纤维和刚性聚合物的悬浮进行严格的动态模拟，其中包括多体流体动力相互作用。拟议的实验和模拟结果有望为深入了解布朗纤维的动力学，以及微观流变学和宏观流变学测量之间的关系提供重要的见解。将实施一项综合教育计划，重点是将随机过程和模型纳入化学工程本科课程。其目标是让学生熟悉随机过程的基本原理，这对新兴的生物技术和纳米技术领域很重要；目前课程中缺乏这些主题，这是化学工程毕业生充分参与这些技术领域的一个严重障碍。为了解决这一重大问题，PI正在开发高度结构化的计算机模块，这些模块将实现一个自学系统，并利用计算机的模拟能力。这些概念将使用主要取自生物技术领域的例子加以说明。这种方法将为学生提供与生物技术相关的基本过程的洞察力，同时他们将学习随机过程的原理。这些单元将用作现有课程的教学工具或补充材料。一旦完成，这些单元将通过互联网和其他可用的手段传播给教育工作者。为了进一步加强对学生的教育，PI正在继续改进和扩大有效方法在教学中的使用，并通过直接参与研究计划向各级学生提供技术培训和职业咨询。广泛的影响通过计算将导致布朗柱的半稀溶液理论的改进，强调了拟议研究的意义。刚性聚合物被广泛用作高性能塑料，布朗纤维的例子可以以生物来源的大分子的形式存在，也可以在纳米技术中以纳米管和纳米棒的形式找到。因此，这项研究将对聚合物科学、纳米技术和生物技术的现有和新兴技术产生直接影响。教育计划致力于为学生提供参与新兴生物技术和纳米技术领域的技能的必要性。教学工具的开发和实施将满足这一需求，并培养一支接受过适当培训的技术队伍，以便参与这些新技术。这一努力将改善大学学生的教育体验和结果；此外，最终产品将传播给其他教育工作者，从而影响更多的学生。

AbstractCTS-0348205J. Butler, U of FloridaThe general objective of the research program is to elucidate the dynamics and rheology of suspensions of Brownian rods while simultaneously developing microrheology as a tool for characterizing complex fluids containing rigid, Brownian particles. Improving the performance and creating new applications for materials made with rigid polymers and Brownian fibers partly relies upon the accurate determination of their physical properties. To characterize ridgid polymers and Brownian fibers, materials scientists and engineers measure quantities such as the particle diffusivities and fluid rheology. Interpretation of the results depends upon theories which usually provide qualitative scaling laws rather than quantitative predictions. To eliminate the disparity between quantitative predictions and measurements, a combined program of experimental and computational research is being pursued. The experimental program uses microrheology to evaluate the linear viscoelastic response of a suspension of isotropic Brownian rods and to measure the viscosity of a suspension of Brownian rods aligned by a shear flow. A direct comparison with measurements of standard shear-rheology will be made on the identical suspension. Simulations of the rheology and microrheology will be used in interpreting the measurements. These simulations will be the first rigorous and dynamic simulations for a suspension of Brownian fibers and rigid polymers which include multi-body hydrodynamic interactions. The results of the proposed experiments and simulations are anticipated to provide significant insight into not only the dynamics of Brownian fibers, but also the relationship between microrheology and macrorheology measurements.An integrated education program focused on incorporating stochastic processes and models into the undergraduate curriculum of chemical engineering will be carried out. The goal is to familiarize students with the fundamentals of random processes which are important to the emerging areas of biotechnology and nanotechnology; the current lack of these topics in the curriculum represents a critical barrier to the full participation of graduates of chemical engineering in these areas of technology. To address this significant issue, the PI is developing highly structured computer modules which will implement a system of self-study and take advantage of the simulation capabilities of the computer. The concepts will be presented using examples taken primarily from the area of biotechnology. This approach will provide the students with insights into fundamental processes associated with biotechnology while they simultaneously study the principles of stochastic processes. The modules will be used as teaching tools or supplementary material in existing courses. Once completed, the modules will be disseminated to educators through the internet and other available means. To further enhance the education of students, the PI is continuing to improve upon and expand the use of effective methods in teaching and is providing technical training and career counseling to students at all levels through direct participation in the research program.Broad ImpactThe significance of the proposed research is underlined by the improvement in the theories of semidilute solutions of Brownian rods which will result from the calculations. Rigid polymers are widely used as high performance plastics and examples of Brownian fibers can be found in the form of macromolecules of biological origin and in nanotechnology in the form of nanotubes and nanorods. Consequently, the research will have a direct impact on existing and emerging technologies in polymer science, nanotechnology, and biotechnology.The education program addresses the necessity of providing students with skills to participate in the emerging fields of biotechnology and nanotechnology. The development and implementation of the instructional tools will meet this need and create a technological workforce with appropriatetraining for participation in these new technologies. This effort will result in an enhanced educational experience and outcome for the students of the University; furthermore, the final products will be disseminated to other educators and therefore impact many additional students.