Theory, simulations and applications for nanostructured polymeric materials

这项研究计划的重点是技术上的重要问题，涉及两类结构的聚合物，特别是嵌段共聚物和聚合物刷。普通聚合物是通过将相同的单体单元连接在一起形成长链分子而合成的，而嵌段共聚物则由不同单体制成的部分（或嵌段）组成。化学上不同的块分离的自然趋势导致这些分子自组装成具有纳米尺寸域的各种并且通常是精细的结构（或形态）。将具有不同特性的聚合物联合收割机组合成有序纳米结构的能力提供了控制材料性质的有力方式。作为可持续聚合物中心（CSP）的一部分，我们将利用这种控制来改善可再生植物基聚合物材料的性能，希望它们能够与传统的石油基材料竞争，甚至超越传统的石油基材料。此外，嵌段共聚物的自组装成纳米尺寸的结构导致在纳米技术中的许多有用的应用。例如，我们感兴趣的是开发用于药物输送的纳米囊泡，在纳米尺度上图案化表面的有效方法，以及智能环境响应纳米结构。聚合物刷代表了另一类在纳米技术中具有许多复杂应用的结构化聚合物。它们是通过将聚合物以足够高的密度通过其末端附着到表面上而形成的，该密度使得拥挤导致聚合物从表面拉伸开。我们将研究由外部电场控制的带电刷，用于纳米尺寸的致动器和通过薄膜门控纳米尺寸的孔。 为了研究这些系统，我的团队将继续发展自洽场理论（SCFT），我被认为是世界领先的专家之一。SCFT允许使用粗粒度微观模型的结构聚合物的精确平均场计算。这是对以前方法的巨大改进，并取得了一系列显著的成功。该理论已经能够模拟非常微妙的影响，预测行为后被实验证实，纠正主要的实验错误，并在实验研究中发挥至关重要的作用。由于其微观性质，SCFT具有高度的预测性，并允许获得许多实验无法测量的量。因此，SCFT经常为其预测提供简单直观的解释。尽管SCFT在有序结构方面有着惊人的记录，但对于波动的无序形态，SCFT变得不准确。然而，将这些波动纳入SCFT的技术，现在出现的场论模拟（FTS）的到来，我们将继续我们的工作，一个有前途的蒙特卡罗变体（MC-FTS）。

This research proposal focuses on technologically important problems involving two classes of structured polymers, specifically block copolymers and polymeric brushes. While ordinary polymers are synthesized by joining together identical monomer units to form long-chain molecules, block copolymers consist of sections (or blocks) made from different monomers. The natural tendency for chemically distinct blocks to separate causes these molecules to self-assemble into various and often elaborate structures (or morphologies) with nanometer-sized domains. The ability to combine polymers with different characteristics into well-ordered nanostructures provides a powerful way of controlling material properties. As part of the Center for Sustainable Polymers (CSP), we will use this control to improve the properties of renewable plant-based polymeric materials in hopes they will compete or even outperform conventional petroleum-based materials. Furthermore, the self-assembly of block copolymers into nano-sized structures leads to many useful applications in nanotechnology. For instance, we are interested in the development of nano-sized vesicles for drug delivery, efficient methods for patterning surfaces on the nanoscale, and smart environmentally-responsive nanostructures. Polymeric brushes represent another class of structured polymers with many sophisticated applications in nanotechnology. They are formed by attaching polymers to a surface by their ends at a sufficiently high density that the crowding causes the polymers to stretch away from the surface. We will study charged polyelectrolyte brushes controlled by an external electric field for applications such as nano-sized actuators and gating nano-sized pores through thin membranes.   To study these systems, my group will continue our development of self-consistent field theory (SCFT), for which I am regarded as one of the world's leading experts. SCFT permits exact mean-field calculations for structured polymers using coarse-grained microscopic models. It is a tremendous improvement over previous approaches and has been rewarded by a series of remarkable successes. The theory has been able to model very subtle effects, predict behaviour later to be confirmed by experiment, correct major experimental errors, and play a vital role in experimental studies. Because of its microscopic nature, SCFT is highly predictive and allows access to many quantities that experiments cannot measure. As a result, SCFT routinely provides simple intuitive explanations for its predictions. Despite its amazing track record with ordered structures, SCFT becomes inaccurate for fluctuating disordered morphologies. However, techniques for incorporating these fluctuations into SCFT are now emerging with the advent of field theoretic simulations (FTS), and we will continue our work on a promising Monte Carlo variant (MC-FTS).