Understanding Local Dynamical Gradients Near Dissimilar Polymer-Polymer Interfaces

非技术性总结：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的创造需要了解纳米级的局部特性如何在不同组件之间的界面附近受到影响。 这项研究的目的是解决背后的基本理解，为什么在本地性能的动态梯度可能是特别长范围的不同聚合物的界面附近。 使用局部荧光方法测量材料从液体固化成玻璃的局部温度的实验将在设计用于分离、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的几个系统上作为深度的函数进行。还将探索其他方法来探测这种影响。 研究工作将由研究生和本科生进行，他们将接触到这个跨学科领域的物理，化学和材料科学。 PI通过让这些学生参与旨在促进科学、研究和妇女及少数民族参与的各种教育和外联活动，促进这些学生的培训和科学成长。 技术概要：了解材料的性质如何受到界面相互作用的干扰是一个问题，在许多纳米结构聚合物材料，如薄膜，纳米复合材料，纳米结构共混物和嵌段共聚物中具有广泛的影响。 现有的研究表明，界面扰动可以从几纳米到几十纳米甚至几百纳米的任何地方传播，这取决于所讨论的材料性质，玻璃质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随着与给定界面的距离而变化的理解的基础上，以试图解决为什么两种不同聚合物之间的界面显示出动态梯度，可以跨越数百纳米，并且相对于组成轮廓出乎意料地不对称。 实验将侧重于测试这种意外行为的根本原因，通过测量局部玻璃化转变温度的详细动力学曲线作为各种界面附近深度的函数，通过荧光，可用于测试目前在该领域的理论努力，以及评估这种长程行为与其他实验技术。 直接比较将在几个不同的系统之间进行设计，以分离，隔离，和测试几个因素，可能使这种聚合物-聚合物界面独特的：分子链连接的界面，界面的宽度，界面粗糙度，模量，域大小和冷却速率。 这些努力应该能够去卷积被认为是界面如何改变局部材料特性和动力学的各种因素。

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.