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

嵌段聚合物是一类重要的特种材料，它由两种或两种以上具有不同化学结构的聚合物连接而成，可以在纳米（1/100,000,000英寸）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水净化膜、石化精炼催化剂模板和下一代集成电路的图案转移材料。在化学、化学工程和材料科学交叉的跨学科研究环境中，该研究项目将广泛培养年轻科学家和工程师在假设驱动下，合理设计具有特定物理属性的块体聚合物材料。项目参与者将使用精密合成技术制造新的嵌段聚合物，以探测其纳米级结构和随之而来的性质。该项目的一个关键目标是开发直接聚合物自组织成间隔小于20nm的周期性线和点图案的方法，具有集成电路制造的潜在应用。项目参与者还将为K-8年级的学生进行科学示范活动，培养他们对聚合物不同寻常但有用的特性的认识，以扩大传统上代表性不足的群体在STEM领域的参与。其他外联活动的重点是提高与塑料废物、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：技术概述嵌段聚合物自组装为具有空间周期性纳米级结构域的技术相关材料的分子设计提供了机会，这源于通过共价连接不混溶聚合物片段建立的受挫的自由能量平衡。在线性A/B多嵌段聚合物中，有序的相选择、稳定性和微畴周期性取决于聚合物组成、聚合程度(N)以及与不利的A/B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值和其纳米级形态周期性的下限。这种周期模式在下一代集成电路和位图形数据存储介质的纳米制造中的应用刺激了线性块状物聚合物的发展，其形成低于10纳米的特征。刷状聚合物（聚合物侧链密集接枝于聚合物主链上）在低于20纳米长度尺度上的组装能力尚未得到充分研究。本项目重点研究了核壳嵌段刷（csBB）聚合物的分子结构/自组装关系，这种聚合物是通过ABA三嵌段聚合物的链中点连接而产生的。新的csBB聚合物将被合成并通过x射线散射，流变学和电子显微镜进行表征，以量化其结构诱导的有序能力如何依赖于主链长度和结构，以及侧链段分散性。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，这可能为未来的纳米模板应用提供信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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.