Structural and Architectural Control of Order in Block Copolymers
Abstract
Capitalizing on the microphase-separated morphology in block copolymers depends critically on controlling and optimizing multiple parameters. These include generating uniformly thick films over large areas, controlling the size scale of the microdomains over a broad range of length scales (nm to micrometer), controlling microdomain orientation, perfecting the lateral ordering over macroscopic distances, tailoring the chemical structures to impart functionality, integrating chemistries to enable conversion to hybrid composites, and using chemistries and processing conditions that are easily scalable. Our previous AFOSR-supported efforts to meet these challenges have resulted in the development of acid-catalyzed solid-state conversion that transforms a phase-mixed hydrophobic-hydrophobic block copolymer (BCP) into a strongly microphase-separated hydrophobic-hydrophilic BCP, massively increasing the segmental interaction parameter, ?, to achieve microdomains sub-3 nm in size (the smallest ever achieved using BCP self-assembly). The proposed research will capitalize on this solid-state morphogenesis by decreasing the size scale of the microdomains further to theoretically achievable limits. Static and cyclic gradient conversion methods will be developed to enhance, if not perfect, lateral order, and sequences will be built into the BCP to control orientation. Chemistries will be developed to generate hybrid, flexible nanostructured materials for electronic, thermoelectric, and magnetic devices and metamaterials. In addition to tuning repeat unit chemistries to attain higher incompatibilities and stimuli-responsive behavior, BCP topology will be utilized to control size (in both the small and large extremes) and orientation. Specifically, bottlebrush-type architectures will be employed to achieve spatial and directional control of intermolecular interactions, molecular and microdomain orientation, long-range order, and extended range of periodicities. Ordering over an unprecedented range of length scales will be pursued. Additionally, reversible solid-state transformations from the phase mixed to strongly microphase-separated BCP state will be developed, enabling a cyclic order-to-disorder transition, an intriguing approach to perfect lateral ordering, the Holy Grail for directed self-assembly processes.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502110388
Entities
People
- Thomas Russell
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Massachusetts