Derived from linking two or more polymers with different chemical structures, block polymers are an important class of specialty materials that self-organize into repeating patterns at the nanometer (1/100,000,000 of an inch) length scale. Applications of these structurally periodic materials include advanced water purification membranes, templates for petrochemical refining catalysts, and pattern transfer materials for next-generation integrated circuits. Within an interdisciplinary research environment situated at the crossroads of chemistry, chemical engineering, and materials science, this research project will broadly train young scientists and engineers in hypothesis-driven, rational design of block polymer materials with specific physical attributes. Project participants will use precision synthesis techniques to make new block polymers, in order to probe their nanoscale structures and consequent properties. A key goal of this project is to develop approaches to direct polymer self-organization into periodic line and dot patterns with spacings less than 20 nm, with potential applications for integrated circuit manufacture. Project participants will also engage in scientific demonstration activities for K-8 audiences to cultivate an appreciation for the unusual yet useful properties of polymers, with the aim of broadening participation of traditionally under-represented groups in STEM fields. Additional outreach activities focus on enhancing science literacy around contemporary issues related to plastic waste, recycling, and sustainable plastics use.
Part 2: TECHNICAL SUMMARY
Block polymer self-assembly presents opportunities for molecular design of technologically-relevant materials with spatially periodic nanoscale domains, which stem from the frustrated free energy balance established by covalently linking immiscible polymer segments into a single macromolecule. In linear A/B multiblock polymers, ordered phase selection, stability, and microdomain periodicity depend on polymer composition, degree of polymerization (N), and the energy penalty associated with unfavorable A/B segment contacts. The choice of monomer chemistry sets the A/B contact energy, thereby dictating a minimum N for melt-phase self-assembly and a lower bound on the periodicities of their nanoscale morphologies. Applications of such periodic patterns in nanomanufcaturing of next-generation integrated circuit and bit-patterned data storage media have stimulated development of linear block polymers, which form sub-10 nm features. The ability of brush polymers, in which polymer side chains are densely grafted from a polymer backbone, to assemble at sub-20 nm length scales is less well-explored. This project focuses on detailed studies of molecular structure/self-assembly relationships in core-shell block brush (csBB) polymers, which arise from linking ABA triblock polymers through their chain midpoints. New csBB polymers will be synthesized and characterized by X-ray scattering, rheology, and electron microscopy, in order to quantify how their architecture-induced ordering power depends on the backbone length and structure, and side-chain segmental dispersity. Additionally, fundamental surface wetting and thin film self-assembly characteristics of csBBs will be compared to those of their linear triblock analogues, potentially informing future nanotemplating applications. .ï·
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.
