Ordering of Block Copolymer Systems with Enhanced Molecular Interactions and Diffusional Dynamics

非技术概述：嵌段共聚物是一类多组分聚合物材料，用于广泛的纳米技术的高级应用，从清理漏油的薄膜到光纤光学中的光操纵，再到晶体管的基本元件和高密度数据存储元件。嵌段共聚材料的实际应用通常要求它们形成几何有序结构，如圆柱状或片状(片状)微结构和更复杂的几何结构。虽然嵌段共聚物可以通过分子尺度上的自组装本质上形成这些有序结构，但要在宏观尺度上获得有用的有序结构需要通过加工方法为嵌段共聚物提供足够的分子迁移率。目前使用的是热处理和溶剂蒸汽处理方法，然而，由于担心热降解，这些方法可能会很慢，而且往往不可能实现。这里的研究开发并深入研究了一种快速加工方法，包括将嵌段共聚物浸入多组分混合溶剂中，提供溶胀、非溶胀和嵌段相互作用可调溶剂的可控平衡。一项成功的研究将为嵌段共聚物结构的大规模自组装的连续工业加工铺平道路，用于各种应用。这项研究将通过几项教育和推广活动促进妇女和少数族裔的参与，为化学工程和材料科学研究生开发一门带有实验室模块的聚合物纳米技术课程，并通过实习计划吸引高中生参与实验室研究。技术概述：嵌段共聚物由化学键合的单体序列组成，其自组装能力使其适用于各种潜在的纳米技术应用，从纳米光子学到纳米电子学到纳米多孔膜。要实现这些有序的自组装驱动微结构，需要先进的加工方法来控制形貌和宏观尺度上最小缺陷的长程有序化。虽然热和溶剂蒸气退火法(SVA)是嵌段共聚物有序化的既定方法，但这里的工作将使通过一种新开发的方法对嵌段共聚物进行有序化，包括将其浸入混合溶剂中，同时阐明分子水平对所产生的形态的理解。这种名为直接浸没退火法(DIA)的方法已经展示了快速有序2D圆柱体形成块共聚物薄膜的前景，该方法具有独特的结构域间距控制。本工作将研究DIA诱导的嵌段共聚物膜的有序性，以研究1)BCP嵌段内混合溶剂的化学势控制分配和有序化的活化能，2)本征嵌段共聚物的形态(一维、二维和三维)在干燥状态下对微区崩塌的作用，3)离子液体作为增强有序性和选择性地定向传输功能纳米颗粒的加工助剂，4)DIA和SVA之间的基本动力学和热力学差异，以及5)衬底表面能对DIA诱导的BCP膜的取向和形貌的影响。劳动力方面将包括通过几项教育和外联活动对妇女和少数群体进行培训，开发一门从本科生到研究生的衔接聚合物纳米技术课程，并为高中生提供科学实习机会，从基础到高级学习聚合物。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY:Block copolymers are a class of multicomponent polymeric materials used for advanced applications in a wide range of nanotechnologies, ranging from membranes for cleaning oil spills to optical manipulation of light in fiber optics to fundamental elements of transistors and high-density data storage elements. Practical realization of such applications of block copolymer materials typically require that they form geometrically ordered structures, such as cylindrical or lamellar (sheet-like) microstructure and more complex geometries. While block copolymers can form these ordered structures intrinsically by self-assembly at molecular scales, obtaining ordered structures over macroscopic scales useful for applications requires providing the block copolymer with sufficient molecular mobility via processing methods. Thermal and solvent vapor processing methods are currently used, however, they can be slow and often not possible due to concerns of thermal degradation. The research here develops and examines in-depth a rapid processing approach that involves immersing the block copolymer into multi-component solvent mixtures that offer a controllable balance of swelling, non-swelling and block-interactions-tunable solvents. A successful research will pave the way for continuous roll-to-roll industrial processing for large-scale self-assembly of block copolymer structures for various applications. The research will promote participation of women and minorities through several educational and outreach activities, develop a polymer nanotechnology course with a laboratory module for Chemical Engineering and Materials Science graduate students, and engage high school students in laboratory research with internship programs. TECHNICAL SUMMARY:Block copolymers consist of chemically bonded monomer sequences whose ability to self-assemble renders them applicable for various potential nanotechnology applications, ranging from nanophotonics to nanoelectronics to nano-porous membranes. To accomplish these ordered self-assembly-driven microstructures requires advanced processing methods for controlled morphology and long-range order with minimal defects over macroscopic scales. While thermal and solvent vapor annealing (SVA) are established methods of block copolymer ordering, the work here will enable ordering of block copolymers annealed by a newly developed method involving its immersion in a mixture of solvents, while at the same time elucidating molecular-level understanding of the resulting morphology. Termed Direct Immersion Annealing, or DIA, the method has already demonstrated promise for rapid ordering of 2D cylinder-forming block copolymer films with unique control over domain spacing. The present work will examine DIA induced ordering of block copolymer films to study 1) chemical-potential controlled partitioning of solvent mixture within BCP blocks and activation energy of ordering, 2) role of intrinsic block copolymer morphology (1D, 2D, and 3D) on domain collapse in dry state, 3) ionic-liquid as a processing aid for enhanced ordering and targeted transport of functional nanoparticles selectively within BCP block domains, 4) fundamental kinetic and thermodynamic differences between DIA and SVA, and 5) effect of substrate surface energy on DIA-induced orientation and morphology of BCP films. Workforce aspects will involve the training of women and minorities through several educational and outreach activities, developing a bridging undergraduate-to-graduate polymer nanotechnology course, and provide scientific internships to high school students to learn about polymers, from a basic to an advanced level. .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.