DMREF: Collaborative Research: Polymeric Composites and Foams Based on Two Dimensional Surfactants

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The challenge of mixing different materials such as plastics, particles, and solvents is one of the major factors hindering future advances in the development of functional materials with new or improved properties. A prominent example of this are graphene-based materials, where graphene's extraordinary combination of high strength, surface area, and conductivity cannot yet be fully utilized as graphene sheets tend to clump together and stack due to a lack of compatibility with other materials. Boron nitride sheets are another example of a promising material limited by the same problem. This project attempts to overcome this obstacle by utilizing the high-energy interface between two immiscible solvents to force stacked graphene sheets to exfoliate and spread. The understanding of governing physical principles of surface activity of graphene and boron nitride produced by this activity will be applied to form emulsions that serve as precursors for the synthesis of foam-like materials reinforced with graphene or boron nitride with optimized mechanical and electrical properties. These reinforced polymeric materials have the potential to be used as strong and lightweight structural materials, electrodes in capacitors and batteries, substrates for flexible electronics, electrically conductive, high surface area catalyst supports, and super-absorbent materials. The project will also be of societal benefit as a result of outreach activities built on the Chemistry Wizards Program designed to target middle school children learning about scientific inquiry. The program aims to spur students from underrepresented populations to pursue post-secondary study and careers in STEM fields.Mixing of chemically and physically different species such as polymer chains, colloidal particles, and solvents is one of the major factors hindering future advances in the development of functional materials. A prominent example of this are graphene based polymeric materials, where graphene's lack of compatibility/solubility is commonly overcome by approaches that compromise its superior electrical, thermal, and mechanical properties and make the composite materials less attractive for future development. This project attempts to overcome this obstacle by utilizing the high-energy interface between two immiscible solvents to force stacked graphene sheets to exfoliate and spread. Lowering the overall free energy of the system drives this rearrangement of sheets. This research is centered on the development of a unifying theoretical, computational and experimental framework to describe the behavior of two-dimensional materials at the liquid/liquid interface. The approach is multi-scale, reaching from the atomic to mesoscopic dimensions. Using graphene and boron nitride as examples, this work will reveal general selection principles for solvent pairs and reaction conditions for which the novel concept of using two-dimensional sheets as surfactants can be realized. The understanding of the governing physical principles of surface activity of graphene and boron nitride will be applied to form emulsions that serve as precursors for the synthesis of foam-like materials reinforced with graphene or boron nitride. The developed theoretical and computational models of these composite foams aim at the design of materials with optimized mechanical and electrical properties. These design tools will be tested and calibrated through experimental studies at nano- and meso-length scales. Ultimately, the work will outline design principles for nanostructured, multifunctional, two-dimensional surfactant-reinforced polymeric composites with tailored properties, enabling material development in a fraction of the time that would be required by a trial and error approach alone. The reinforced polymeric materials have the potential to be used as strong and lightweight structural materials, electrodes in capacitors and batteries, substrates for flexible electronics, electrically conductive, high surface area catalyst supports, and super-absorbent materials. The project will also be of societal benefit as a result of outreach activities built on the Chemistry Wizards Program designed to target middle school children learning about scientific inquiry. The program aims to spur students from underrepresented populations to pursue post-secondary study and careers in STEM fields.