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

第 1 部分：非技术摘要嵌段聚合物源自连接两种或多种具有不同化学结构的聚合物，是一类重要的特种材料，可在纳米（一英寸的 1/100,000,000）长度范围内自组织成重复图案。这些结构周期性材料的应用包括先进的水净化膜、石化精炼催化剂的模板以及下一代集成电路的图案转移材料。在位于化学、化学工程和材料科学交叉口的跨学科研究环境中，该研究项目将广泛培训年轻科学家和工程师，以假设为导向，合理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，以探究其纳米级结构和随之而来的特性。该项目的一个关键目标是开发将聚合物自组织直接形成间距小于 20 nm 的周期线和点图案的方法，并在集成电路制造中具有潜在的应用。项目参与者还将为 K-8 观众开展科学演示活动，培养对聚合物不寻常但有用的特性的欣赏，目的是扩大 STEM 领域传统上代表性不足的群体的参与。其他外展活动的重点是提高围绕与塑料废物、回收和可持续塑料使用相关的当代问题的科学素养。第 2 部分：技术摘要嵌段聚合物自组装为具有空间周期性纳米级域的技术相关材料的分子设计提供了机会，这种材料源于通过将不混溶的聚合物片段共价连接成单个大分子而建立的受挫的自由能平衡。在线性 A/B 多嵌段聚合物中，有序相选择、稳定性和微域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损失。单体化学的选择决定了 A/B 接触能，从而决定了熔融相自组装的最小 N 值和纳米级形态周期性的下限。这种周期性图案在下一代集成电路和位图案数据存储介质的纳米制造中的应用刺激了线性嵌段聚合物的发展，这种聚合物形成了亚10纳米的特征。刷状聚合物（聚合物侧链从聚合物主链上密集接枝而成）在低于 20 nm 长度尺度上组装的能力尚未得到充分研究。该项目重点详细研究核-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。新的 csBB 聚合物将通过 X 射线散射、流变学和电子显微镜进行合成和表征，以量化其结构诱导的有序能力如何取决于主链长度和结构以及侧链片段分散性。此外，csBB 的基本表面润湿和薄膜自组装特性将与其线性三嵌段类似物进行比较，这可能为未来的纳米模板应用提供信息。 .该奖项反映了 NSF 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.