Collaborative Research: Self-Assembly of Polymer Grafted Nanoparticles

智力优势：该提案的重点是通过将无机纳米粒子与有机聚合物各向同性接枝而产生的新型材料。由于无机纳米颗粒和有机聚合物通常彼此不喜欢，这些混合颗粒表现得像纳米颗粒两亲物。通过类比两亲物，这些混合粒子可以自组装成一系列与物理和生物科学中的许多应用直接相关的超结构。初步计算表明，这种自组装反应的能量增益之间的平衡时，粒子分数的方法与扭曲的接枝聚合物的熵损失。PI计划从理论上考虑这个问题，开始通过描绘这些自组装结构形成的参数空间区域，以及它们是平衡的而不是服从动力学控制的时间演变结构。展望未来，我们会问更复杂的结构，如与嵌段共聚物接枝的颗粒可能会表现。这个问题的灵感来自于已经预测并从三嵌段共聚物中获得的结构的大生态学。PI还将这些想法扩展到其他纳米颗粒形状，例如，纳米棒和纳米片，并检查可能出现的纳米颗粒组装体的形状。同样，受嵌段共聚物的广泛实验活动的启发，PI质疑外部场的作用（例如，流、电、磁）来引导形成的超结构。总体目标是先设计出各向同性装饰的纳米颗粒，这些纳米颗粒可以自发地组装成越来越复杂的超结构。虽然这些问题是进口从一个基本的观点，他们将是特别的实际利益，因为他们提供了独特的手段来控制全球纳米粒子的分散状态，因此宏观性能，聚合物纳米复合材料。PI提出了两个PI之间的合作努力，他们将联合收割机结合计算机模拟和平均场理论，以解决我们对纳米粒子两亲物自组装（和定向组装）的初步理解的基础问题。PI已经积极合作了二十多年，PI为拟议的研究带来了独立但互补的技能。地理上的接近和共同的研究生也极大地促进了这项研究，并强调了拟议活动的协同性质。更广泛的影响：修饰的纳米颗粒自组装成任意复杂的超结构的能力，以及通过使用外部场来指导这种组装过程的能力，可以从根本上改变我们设计具有所需宏观性质的纳米颗粒组装体（以及因此聚合物纳米复合材料）的能力。除了这些研究活动外，PI将继续制定针对代表性不足的少数民族的REU方案。PI应利用FAMU，一所合作学校，是一所历史上的黑人学校，并利用这一点来招募本科生，目的是让他们留在科学领域。

Intellectual Merit: The focus of this proposal is novel materials created by isotropically grafting inorganic nanoparticles with organic polymers. Since the inorganic nanoparticles and organic polymers typically dislike each other, these hybrid particles behave like nanoparticle amphiphiles. By analogy to amphiphiles, these hybrid particles can self assemble into a range of superstructures of immediate relevance to many applications in the physical and biological sciences. Preliminary calculations suggest that this self assembly reflects a balance between the energy gain when particle scores approach versus the entropy loss of distorting the grafted polymers. The PIs plan to consider this issue theoretically and begin by delineating regions of parameter space where these self assembled structures are formed, and where they are equilibrium rather than temporally evolving structures amenable to kinetic control. Looking ahead, we ask how more complicated architectures, such as particles grafted with block copolymers might behave. This question is inspired by the large zoology of structures that have been predicted and obtained from triblock copolymers. The PIs also extend these ideas to other nanoparticle shapes, e.g., nanorods and nanosheets, and examine what shapes of nanoparticle assemblies may arise. Again, inspired by a broad range of experimental activities on block copolymers, the PIs query the role of external fields (e.g., flow, electric, magnetic) in directing the superstructures that form. The overarching goal is to a prior design isotropically decorated nanoparticles that can spontaneously assemble into progressively more complex superstructures. While these questions are of import from a fundamental viewpoint, they will be of particular practical interest since they provide unique means of controlling the global nanoparticle dispersion state, and hence the macroscopic properties, of polymer nanocomposites. The PIs propose a collaborative effort between two PIs, who will combine computer simulations and mean-field theory to tackle fundamental issues underpinning our nascent understanding of self-assembly (and directed assembly) of nanoparticle amphiphiles. The PIs have collaborated actively for over twenty years, and the PIs bring separate but complementary skill sets to the proposed research. The geographical proximity, and shared graduate students, also strongly facilitate this research and emphasizes the synergistic nature of the activities proposed. Broader Impact: The ability of decorated nanoparticles to self assemble into superstructures of arbitrary complexity, and the ability to direct this assembly process through the use of external fields, could fundamentally alter our ability to design nanoparticle assemblies (and hence polymer nanocomposites) with desired macroscale properties. Apart from these research activities, the PIs shall continue to develop REU programs targeting underrepresented minorities. The PIs shall utilize the fact that FAMU, a partner school, is a historically black school, and use this to recruit undergraduate students with the goal of retaining them in the sciences.