Collaborative Research: Self-Assembly of Polymer Grafted Nanoparticles

智能优点：这项提议的重点是通过各向同性将无机纳米颗粒与有机聚合物接枝而产生的新型材料。由于无机纳米粒子和有机聚合物通常互不喜欢，这些杂化粒子的行为就像纳米粒子两亲性。通过类似于两亲分子，这些杂化颗粒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，这种自组装反映了粒子分数接近时的能量增益与扭曲接枝聚合物的熵损失之间的平衡。PI计划从理论上考虑这一问题，并从描绘参数空间的区域开始，这些自组装结构在哪里形成，在哪里它们是平衡的，而不是服从于运动控制的时间演化的结构。展望未来，我们想知道更复杂的结构，比如接枝了嵌段共聚物的颗粒可能会有什么样的表现。这个问题的灵感来自于从三嵌段共聚物中预测和获得的结构的大生态。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件的形状。同样，受嵌段共聚物的广泛实验活动的启发，PI质疑外场(例如，流动、电、磁)在引导形成的超结构中的作用。首要目标是预先设计一种各向同性装饰的纳米颗粒，这种纳米颗粒可以自发地组装成越来越复杂的超结构。虽然这些问题从根本上来说是重要的，但它们将特别具有实际意义，因为它们提供了控制全球纳米粒子分散状态的独特手段，从而控制了聚合物纳米复合材料的宏观性质。PI提出了两个PI之间的合作努力，他们将结合计算机模拟和平均场理论来解决基本问题，这些问题奠定了我们对纳米粒子两亲分子自组装(和定向组装)的初步理解。20多年来，私人投资机构一直积极合作，并为拟议的研究带来了独立但互补的技能集。地理上的接近和研究生的共享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，以及通过使用外场来指导这种组装过程的能力，可能从根本上改变我们设计具有所需宏观性能的纳米颗粒组件(从而聚合物纳米复合材料)的能力。除这些研究活动外，私人投资机构应继续制定针对代表人数不足的少数民族的区域教育联盟方案。PIS应利用伙伴学校FAMU是一所历史上的黑人学校这一事实，并利用这一点来招收本科生，目标是留住他们在科学领域。

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.