New ideas and new materials in polymer science

本提案旨在解决软凝聚态物理中一些最困难的突出问题。许多软固体是玻璃状的（无定形固体）。玻璃可以被认为是最常见的固体，因为只要足够快的冷却，即使是通常采用晶体结构的材料也可以被制成玻璃。尽管它们的重要性，无论是作为技术上重要的材料，还是作为凝聚态物质的最常见形式之一，我们对玻璃的形成缺乏深刻的理论理解。玻璃实验研究面临的挑战之一是与玻璃材料相关的非常长的松弛时间，因为这导致材料本质上失去平衡，并在无限期的时间内继续老化（随时间变化）。最近发现的稳定玻璃——那些模仿了数千年甚至数百万年的玻璃的玻璃——是我们寻找接近平衡的玻璃系统来研究的理想候选者。我们将通过制造和研究第一个由聚合物制成的稳定玻璃，继续探索对玻璃和玻璃形成的理解。我们将把这与我们的理论努力结合起来，旨在提供一个更简单的框架来理解玻璃材料的许多物理特性。除了我们对玻璃固体的研究，我们也将探索聚合物的结晶度。许多聚合物是部分结晶的，我们将研究高度单分散的小聚合物，以加深我们对聚合物中晶体形成的理解。众所周知，聚合物表现出各种形式的自组装，其中一种形式是一种物质在表面的分离。链末端的情况特别有趣，因为分离的驱动力纯粹是熵的。由于链端偏析的驱动力较弱，使得研究具有很大的挑战性。我们将提供一个明确的答案，表面偏析的存在和程度的聚合物共混物具有不同的分子量值，从而提供链端偏析的实验验证。所有的实验项目都将利用我们的新技术直接物理气相沉积聚合物。该技术允许分离小聚合物分子（由<~ 10个单体单元组成），具有前所未有的单一性和批量。我们的新技术还能够重新定义固体聚合物如何沉积在衬底上，并为软纳米技术开辟了新的途径。总的来说，该提议对我们对软凝聚态物质的基本理解和这些材料的技术应用都有很大的影响。

This proposal aims to tackle some of the most difficult outstanding problems in soft condensed matter physics. Many soft solids are glassy (amorphous solids). Glasses could be argued to be the most common solids, as with sufficiently rapid cooling, even materials that usually adopt a crystalline structure can be made to form a glass. Despite their importance, both as technilogically important materials, and as one of the most common forms of condensed matter, we lack a deep theoretical understanding of the formation of glasses. One of the challenges that face the experimental study of glasses is the very long relaxation times associated with glassy materials, as this results in materials that are inherently out of equilibrium, and continue to age (change over time) for indefinite time periods. The recent discovery of stable glasses - those which mimic glasses that have aged for thousands over even millions of years- are ideal candidates as we look for near equilibrium glassy systems to study. We will continue on our quest to develop an understanding of glasses and glass formation by making and studying the first stable glasses made from polymers. We will couple this with our theoretical efforts that aim to provide a more simple framework to understand much of the physics of glassy materials. In addition to our study of glassy solids, we will also explore aspects of crystallinity in polymers as well. Many polymers are partially crystalline, and we will study highly monodisperse small polymers in order to deepen our understanding of crystal formation in polymers. Polymers are known to exhibit various forms of self assembly, and one form of this is segregation of one species to the surface. The case of chain ends is particularly interesting as the driving force for segregation is purely entropic. The weak driving force from chain end segregation makes it very challenging to study. We will provide a definitive answer to the existence and extent of surface segregation in blends of polymer with different values of molecular weight, and thus provide experimental verification of chain end segregation. All of the experimental projects will utilize our new technique of direct physical vapour deposition of polymers. This technique allows for the isolation of small polymer molecules ( comprised of <~ 10 monomer units) with unprecedented monodsipersity and in bulk quantities. Our new technique also has the ability to redefine how solid polymers can be deposited onto a substrate, and opens up new avenues in soft nanotechnology. Overall, the proposal has great promise for impact in both our fundamental understanding of soft condensed matter and the technological applications of these materials.