Intellectual Merits of Proposed Activities The 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 Activities The 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.
Future technological progress necessitates the design and control of nanoscale membranes, and new methods for the creation of materials with tunable structures, processability, transport properties, and mechanical properties must be perfected. Unfortunately, many designer systems require a tradeoff between the desired and safest chemical components, and the optimal chemical, transport, and mechanical properties. To overcome this dilemma, we are developing chemical synthesis methods to control the nanometer scale (1/1000th the width of a human hair) interfaces in membrane materials to permit the independent tuning of those properties. By enabling the design, synthesis, and stabilization of nanoscale interfaces in analytical (biological) separation membranes, ion-conduction membranes, and nanoscale templates using tapered block copolymers, the cost- and energy-efficient fabrication of next-generation devices can be realized for alternative energy, data storage, and biological applications. Intellectual Merit: We employed specialized polymer systems with controllable junction points to enable the on-demand assembly of materials for use in flexible nanoscale systems. We successfully generated a variety of materials that can be specifically used for membrane separations (bio-separations and lightweight/flexible battery membranes), as well as developed processing conditions for nanostructured thin film templates that are ideal materials for the future development of efficient data storage systems. Key results were highlighted in multiple publications in the peer-reviewed literature. Broader Impact: In addition to materials design, we engaged in a variety of educational and outreach activities that had a substantial and positive impact on the community. We partnered with the American Chemical Society and laboratories at the University performing cutting edge research to provide internship opportunities for high school and college undergraduate students from groups underrepresented in science and engineering. In part based on their laboratory experiences, many of these students have decided to continue their educational endeavors. Additionally, the principal investigator of this project, designed and taught a new nanoscale materials course, and revitalized an introduction to polymer course that reached well over 100 students during this project. Many of these activities have catalyzed similar outreach initiatives across our University campus.
