CAREER: Controlling Block Copolymer Interactions using Tapering between Blocks to Stabilize Networks

本项目的目标是为膜应用创造新的聚合物材料，膜的功能依赖于有序、周期性结构的组装。为了实现这一目标，PI将通过对块状和超薄膜嵌段共聚体系的内部(嵌段到嵌段)和外部(衬底)界面的化学操作，全面了解嵌段共聚的网络行为。通过开发对界面相互作用的更好控制，他将为锂离子电池和直接甲醇燃料电池膜等应用创造新的纳米结构材料。这项研究提案有两个具体目标。第一个目标是控制嵌段共聚聚合物链段之间界面区域的化学组成，以使分离强度与相对分子质量和化学成分脱钩。通过反应化学反应使单体组成逐渐变细，将通过人为地控制自组装结构中的嵌段相互作用和界面宽度来控制分离强度。这将使离子导电和高分子量体系中网络的合成和稳定成为可能，并极大地增加嵌段共聚物在膜应用中的用途。他将采用一种新的锥化设计方法，计算所需的锥化长度，以模拟高相对分子质量锥形共聚物中弱到中等分离强度网络的界面特征。第二个目标是控制超薄嵌段共聚物膜的基片表面能，以产生稳定的多重连续网络结构。在这里，PI将研究具有不同表面能的衬底上的超薄三嵌段共聚物薄膜。通过分析薄膜的行为作为底物化学的函数，目的是揭示表面相互作用对共聚网络组装的影响。这项研究的意义在于通过选择性地调整衬底表面能在超薄聚合物薄膜中生成纳米结构网络。拟议活动的广泛影响本提案中描述的研究为培养学生应对纳米技术中的关键科学和工程挑战提供了一个平台。研究的多面性将允许学生探索化学、化学工程和材料科学的各个方面，使他们接触到纳米材料固有的结构/性质关系。此外，项目中存在灵活性，以便学生可以通过假设驱动的研究来释放他们自己的创造力。本提案介绍了具体的更广泛的影响和教育举措，主要侧重于增加未被充分代表的群体对化学科学的参与。这些举措包括：与特拉华州立大学化学系建立聚合物科学课程合作伙伴关系，为特拉华大学化学系本科生提供暑期研究和指导机会，以及在特拉华州立大学开发相关和刺激的软材料课程。此外，作为计划小组委员会的成员、前学者和导师，PI继续参与美国公民自由联盟少数群体学者计划，这使他在这一重要的更广泛领域具有重要影响。

Intellectual Merits of Proposed ActivitiesThe goal of this project is to create new polymeric materials for membrane applications, where functionality depends on the assembly of ordered, periodic structures. To achieve this aim, the PI will develop a comprehensive understanding of block copolymer network behavior through chemical manipulation of the internal (block-to-block) and external (substrate) interfaces in bulk and ultrathin-film block copolymer systems. By developing greater control over interfacial interactions he will generate new nanostructured materials for applications such as lithium-ion battery and direct methanol fuel cell membranes.There are two specific aims of this research proposal. The first aim is to manipulate the chemical composition of the interfacial region between block copolymer segments to decouple segregation strength from molecular weight and chemical constituents. Tapering of the monomer composition through reaction chemistry will control segregation strength by artificially manipulating block interactions and interfacial width in the self-assembled structures. This will enable the synthesis and stabilization of networks in ion-conducting and high molecular weight systems and dramatically increase the utility of block copolymers in membrane applications. He will employ a new design approach to tapering, calculating the required taper lengths necessary to mimic the interfacial characteristics of weak to intermediate segregation strength networks in high molecular weight tapered copolymers. The second aim is to control substrate surface energy in ultrathin block copolymer films to generate stable multiply-continuous network structures. Here, the PI will investigate ultrathin triblock copolymer films on substrates with varying surface energies. Through analysis of the thin film behavior as a function of substrate chemistry with the aim to uncover the influence of surface interactions on copolymer network assembly. The significance of this research aim lies in the generation of nanostructured networks in ultrathin polymer films by selectively adjusting the substrate surface energies.Broader Impacts of Proposed ActivitiesThe research described in this proposal provides a platform for training students to address key scientific and engineering challenges in nanotechnology. The multifaceted nature of the research will permit students to explore aspects of chemistry, chemical engineering, and materials science, exposing them to the structure/property relationships inherent in nano-materials. In addition, flexibility exists within the project so that students may unlock their own creativity through hypothesis-driven research. Specific broader impact and educational initiatives, with a major focus on increasing the participation of underrepresented groups in the chemical sciences are described in this proposal. These initiatives include: Developing a polymer science course partnership with the Chemistry Department at Delaware State University (DSU), providing summer research and mentorship opportunities for DSU undergraduate students at the University of Delaware, and developing a relevant and stimulating soft materials course at UD. Additionally, the PI's continued involvement in the ACS Minority Scholars Program as a member of the Program Subcommittee, former Scholar, and mentor places him in an excellent position for a significant impact in this important broader area.