Understanding Local Dynamical Gradients Near Dissimilar Polymer-Polymer Interfaces

非技术概述：创造药物输送、先进过滤、电池离子传导或太阳能电池光电发电等技术所需的新材料，需要了解不同组件之间的界面附近纳米级的局部化性质是如何受到影响的。这项研究旨在解决为什么局部性质的动态梯度可能在不同聚合物的界面附近特别长范围的背后的基本理解。使用局部荧光法测量材料从液体凝固到玻璃的局部温度的实验将在几个系统上作为深度的函数进行，这些系统旨在分离、隔离和测试可能使这种聚合物-聚合物界面独特的几个因素。此外，还将探索探索这种影响的其他方法。研究工作将由研究生和本科生进行，他们将接触到这个连接物理、化学和材料科学的跨学科领域。通过让这些学生参与旨在促进妇女和少数群体参与科学、研究和参与的各种教育和外展活动，促进这些学生的培训和科学成长。技术摘要：了解材料的性质如何受到界面相互作用的影响是一个广泛影响众多纳米结构聚合物材料的问题，如薄膜、纳米复合材料、纳米结构共混物和嵌段共聚物。现有的研究表明，界面扰动可以从界面传播到从几纳米到几十纳米甚至数百纳米的任何地方，这取决于所讨论的材料的性质，玻璃材料似乎对界面扰动特别敏感。这项研究的目的是建立在我们对聚合物材料的局部性质如何作为与给定界面的距离的函数的理解的基础上，试图解决为什么两个不同聚合物之间的界面显示出可以跨越数百纳米的动态梯度，并且在组成分布方面出人意料地不对称。实验将专注于测试这种意外行为的根本原因，方法是通过荧光测量不同界面附近局部玻璃转变温度随深度的详细动态分布，这可用于测试该领域当前的理论工作，以及使用其他实验技术评估这种远程行为。将在几个不同的系统之间进行直接比较，这些系统旨在分离、隔离和测试可能使此类聚合物-聚合物界面独特的几个因素：界面上的分子链连接性、界面宽度、界面粗糙度、模数、微区大小和冷却速度。这样的努力应该能够消除各种因素，这些因素被认为是导致界面如何改变当地材料性质和动力学的原因。

NON-TECHNICAL SUMMARY:The creation of new materials necessary for technologies such as drug delivery, advanced filtration, ion conduction for batteries, or photoelectric generation for solar cells requires the understanding of how localized properties at the nanoscale are affected near interfaces between different components. This research aims to address the fundamental understanding behind why dynamical gradients in local properties may be particularly long-ranged near interfaces of dissimilar polymers. Experiments measuring the local temperature at which the material solidifies from a liquid to a glass using a localized fluorescence method will be performed as a function of depth on several systems designed to separate, isolate, and test several factors that may make such polymer-polymer interfaces unique. Additional methods to probe this effect will also be explored. The research efforts will be carried out by graduate and undergraduate students who will be exposed to this interdisciplinary field bridging physics, chemistry, and materials science. The PI fosters training and scientific growth in these students by engaging them in various educational and outreach activities designed to promote science, research, and participation of women and minorities. TECHNICAL SUMMARY: Understanding how the properties of materials are perturbed by interfacial interactions is an issue that has widespread impact across numerous nanostructured polymeric materials such as thin films, nanocomposites, nanostructured blends, and block copolymers. Existing studies have shown that interfacial perturbations can propagate anywhere from a few nanometers to tens and even hundreds of nanometers from the interface depending on the material property in question, with glassy materials appearing to be particularly sensitive to interfacial perturbations. This research aims to build on our understanding of how the local properties of polymer materials change as a function of distance from a given interface to try to address why interfaces between two dissimilar polymers show dynamical gradients that can span hundreds of nanometers and are unexpectedly asymmetric with respect to the composition profile. Experiments will focus on testing the underlying causes for this unexpected behavior by measuring detailed dynamical profiles of local glass transition temperature as a function of depth near various interfaces via fluorescence that can be used to test current theoretical efforts in the field, as well as assessing such long range behavior with other experimental techniques. Direct comparisons will be made between several different systems designed to separate, isolate, and test several factors that may make such polymer-polymer interfaces unique: molecular chain connectivity across the interface, breadth of interface, interfacial roughness, modulus, domain size and cooling rate. Such efforts should be able to deconvolve various factors believed to be responsible for how interfaces alter local material properties and dynamics.