Bulk and Thin Film Self-Assembly of Core-Shell Block Brush Polymers

第一部分：非技术总结嵌段聚合物源于两种或两种以上具有不同化学结构的聚合物，是一类重要的特种材料，可以在纳米(1/100,000,000英寸)的长度尺度上自组织成重复的图案。这些结构周期性材料的应用包括先进的净水膜、用于石化精炼催化剂的模板以及用于下一代集成电路的图案转移材料。在一个位于化学、化学工程和材料科学的十字路口的跨学科研究环境中，该研究项目将广泛培训年轻的科学家和工程师，让他们在假设的驱动下，合理地设计具有特定物理属性的嵌段聚合物材料。项目参与者将使用精密合成技术来制造新的嵌段聚合物，以探索其纳米级结构和相应的性能。该项目的一个关键目标是开发一种方法，将聚合物自组装成间距小于20 nm的周期线和点图案，具有潜在的集成电路制造应用。项目参与者还将为8岁以下的受众开展科学演示活动，培养他们对聚合物不同寻常但有用的特性的认识，目的是扩大传统上代表性不足的群体在STEM领域的参与。其他外展活动侧重于提高与塑料废物、回收和可持续塑料使用有关的当代问题的科学素养。第2部分：技术总结嵌段聚合物自组装为具有空间周期性纳米尺度结构域的技术相关材料提供了分子设计的机会，这些纳米尺度结构域源于通过将不相容的聚合物链段共价连接成单一大分子而建立的受挫的自由能量平衡。在线性A/B多嵌段聚合物中，有序相选择、稳定性和微区周期性取决于聚合物组成、聚合度(N)以及与不利的A/B链段接触相关的能量惩罚。单体化学的选择设定了A/B接触能，从而决定了熔相自组装的最小N和它们纳米级形貌的周期的下限。这种周期性图案在下一代集成电路和位图案化数据存储介质的纳米制造中的应用刺激了形成亚10 nm特征的线性嵌段聚合物的发展。刷状聚合物的能力，即聚合物侧链从聚合物主干上密集接枝，在20 nm以下的长度范围内组装的能力，还没有得到很好的探索。本项目的重点是详细研究核壳嵌段刷(CsBB)聚合物的分子结构/自组装关系，这种聚合物是通过链中点连接ABA三嵌段聚合物而产生的。将合成新的csBB聚合物，并用X射线散射、流变学和电子显微镜对其进行表征，以量化其结构诱导的有序性如何依赖于主链的长度和结构以及侧链的链段分散性。此外，csbbs的基本表面润湿和薄膜自组装特性将与它们的线性三嵌段类似物进行比较，可能为未来的纳米模板应用提供信息。这一奖项反映了国家科学基金会的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1: NON-TECHNICAL SUMMARYDerived from linking two or more polymers with different chemical structures, block polymers are an important class of specialty materials that self-organize into repeating patterns at the nanometer (1/100,000,000 of an inch) length scale. Applications of these structurally periodic materials include advanced water purification membranes, templates for petrochemical refining catalysts, and pattern transfer materials for next-generation integrated circuits. Within an interdisciplinary research environment situated at the crossroads of chemistry, chemical engineering, and materials science, this research project will broadly train young scientists and engineers in hypothesis-driven, rational design of block polymer materials with specific physical attributes. Project participants will use precision synthesis techniques to make new block polymers, in order to probe their nanoscale structures and consequent properties. A key goal of this project is to develop approaches to direct polymer self-organization into periodic line and dot patterns with spacings less than 20 nm, with potential applications for integrated circuit manufacture. Project participants will also engage in scientific demonstration activities for K-8 audiences to cultivate an appreciation for the unusual yet useful properties of polymers, with the aim of broadening participation of traditionally under-represented groups in STEM fields. Additional outreach activities focus on enhancing science literacy around contemporary issues related to plastic waste, recycling, and sustainable plastics use.Part 2: TECHNICAL SUMMARYBlock polymer self-assembly presents opportunities for molecular design of technologically-relevant materials with spatially periodic nanoscale domains, which stem from the frustrated free energy balance established by covalently linking immiscible polymer segments into a single macromolecule. In linear A/B multiblock polymers, ordered phase selection, stability, and microdomain periodicity depend on polymer composition, degree of polymerization (N), and the energy penalty associated with unfavorable A/B segment contacts. The choice of monomer chemistry sets the A/B contact energy, thereby dictating a minimum N for melt-phase self-assembly and a lower bound on the periodicities of their nanoscale morphologies. Applications of such periodic patterns in nanomanufcaturing of next-generation integrated circuit and bit-patterned data storage media have stimulated development of linear block polymers, which form sub-10 nm features. The ability of brush polymers, in which polymer side chains are densely grafted from a polymer backbone, to assemble at sub-20 nm length scales is less well-explored. This project focuses on detailed studies of molecular structure/self-assembly relationships in core-shell block brush (csBB) polymers, which arise from linking ABA triblock polymers through their chain midpoints. New csBB polymers will be synthesized and characterized by X-ray scattering, rheology, and electron microscopy, in order to quantify how their architecture-induced ordering power depends on the backbone length and structure, and side-chain segmental dispersity. Additionally, fundamental surface wetting and thin film self-assembly characteristics of csBBs will be compared to those of their linear triblock analogues, potentially informing future nanotemplating applications. .This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.