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，用于各种纳米技术的高级应用，从清洁漏油的膜到光纤中光的光学操纵，再到晶体管的基本元件和高密度数据存储元件。嵌段共聚物材料的这种应用的实际实现通常需要它们形成几何有序的结构，例如圆柱形或层状（片状）微结构和更复杂的几何形状。虽然嵌段共聚物可以通过在分子尺度上的自组装内在地形成这些有序结构，但是获得可用于应用的宏观尺度上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移动性。目前使用热和溶剂蒸气处理方法，然而，由于热降解的问题，它们可能是缓慢的并且通常是不可能的。 这里的研究开发并深入研究了一种快速加工方法，该方法涉及将嵌段共聚物浸入多组分溶剂混合物中，该混合物提供溶胀，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各种应用的嵌段共聚物结构的大规模自组装的连续卷对卷工业加工铺平道路。该研究将通过几项教育和宣传活动促进妇女和少数民族的参与，为化学工程和材料科学研究生开发一门具有实验室模块的聚合物纳米技术课程，并让高中生参与实验室研究实习计划。 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。为了实现这些有序的自组装驱动的微结构，需要先进的加工方法来控制形态和长程有序，在宏观尺度上具有最小的缺陷。虽然热和溶剂蒸气退火（SVA）是建立嵌段共聚物排序的方法，这里的工作将使排序的嵌段共聚物退火的一个新开发的方法，涉及其浸泡在溶剂的混合物，而在同一时间阐明分子水平的理解所产生的形态。该方法被称为直接浸没退火（DIA），已经证明可以快速有序地形成二维圆柱形嵌段共聚物薄膜，并对域间距进行独特的控制。本工作将研究DIA诱导嵌段共聚物膜有序化，以研究1）BCP嵌段内溶剂混合物的化学势控制分配和有序化活化能，2）嵌段共聚物固有形态的作用（1D、2D和3D）在干燥状态下的畴塌缩，3）离子液体作为加工助剂，用于增强功能性纳米颗粒在BCP嵌段结构域内的选择性有序化和靶向运输，（4）DIA和SVA在动力学和热力学上的基本差异;（5）衬底表面能对DIA诱导的BCP薄膜取向和形貌的影响。劳动力方面将涉及通过几项教育和外联活动培训妇女和少数民族，开发衔接本科生到研究生的聚合物纳米技术课程，并向高中生提供科学实习机会，以了解从基础到高级的聚合物。该奖项反映了NSF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。

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.