Theory, simulations and applications for nanostructured polymeric materials

这项研究方案集中于涉及两类结构聚合物的重要技术问题，特别是嵌段共聚物和聚合物刷子。普通聚合物是通过将相同的单体单元连接在一起形成一个长链分子来合成的，而嵌段共聚物是由不同单体制成的片段(或嵌段)组成的。化学上截然不同的嵌段相互分离的自然倾向导致这些分子能够自组装成各种结构(或形态)，这些结构(或形态)往往是复杂的，具有纳米级的结构域。将具有不同特性的聚合物组合成有序的纳米结构的能力为控制材料的性能提供了一种强大的方法。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，希望它们能与传统的石油基聚合物材料竞争，甚至超越传统的石油基聚合物材料。此外，嵌段共聚物自组装成纳米结构导致了许多有用的纳米技术应用。例如，我们对开发用于药物输送的纳米微囊、在纳米尺度上绘制表面图案的高效方法以及智能环保纳米结构感兴趣。聚合物刷子代表了另一类在纳米技术中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以足够高的密度附着到表面上形成的，以至于拥挤导致聚合物从表面伸展开来。我们将研究由外部电场控制的带电聚电解质刷，用于纳米驱动器和通过薄膜对纳米孔径进行门控等应用。 -- 为了研究这些系统，我的团队将继续发展自洽场论(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对结构化聚合物进行精确的平均场计算。与以前的方法相比，这是一个巨大的改进，并因一系列显着的成功而得到回报。该理论已经能够模拟非常微妙的效应，预测后来被实验证实的行为，纠正主要的实验错误，并在实验研究中发挥重要作用。由于其微观性质，SCFT具有很高的预测性，并允许访问许多实验无法测量的量。因此，SCFT通常会为其预测提供简单直观的解释。尽管SCFT在有序结构方面的记录令人惊叹，但它对波动的无序形态却变得不准确。然而，随着场论模拟(FTS)的出现，将这些涨落纳入SCFT的技术现在正在出现，我们将继续我们的工作，研究一种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).