Scientists and engineers continue to develop new materials with improved performance in applications such as batteries, water purification, gas uptake, and so on. These novel materials provide the foundation used to create new technologies that impact and improve nearly every facet of modern life. Unfortunately, some of the new materials, such as ionic liquids and eutectic solvents, are difficult to handle by themselves, and they require containment of some kind, limiting their use in practical systems. This research work addresses these current limitations by developing methods to prepare capsules with cores of the specialized liquid wrapped in polymer shells. This approach is made possible by the use of a water-free emulsion that is composed of droplets of the active liquid dispersed in an oil, coupled with polymerization techniques. The water-free emulsions are critical to the development of this encapsulation system, as they allow the specialized liquid to remain pure and unadulterated. The work addresses how the composition of the polymer shell impacts performance properties of the capsules, namely mechanical properties and the uptake of gaseous carbon dioxide. This research promotes progress in the areas of composite materials with applications in critical areas such as energy storage and gas separations. In addition to the research, this project will support the training of undergraduate and graduate students and development of How-To Videos. These videos are planned to be publicly available and to show new researchers how to use scientific instruments to characterize polymer-based materials, thereby supporting the development and training of scientists and engineers more broadly.
The goal of the planned research is to develop methods to prepare capsules with cores of active liquids (e.g., ionic liquids and deep eutectic solvents) and polymer composite shells of varied permeability, stability, and mechanical properties. This will be accomplished by leveraging interfacial polymerizations in non-aqueous emulsions. Alkylated graphene oxide (GO) nanosheets will be used as particle surfactant to stabilizing Pickering emulsions, toluene or octane will be used as the continuous phase, and ionic liquid or deep eutectic solvent as the discontinuous phase. Aim 1 focuses on preparing capsule shells of varied permeability and mechanical properties using telechelic oligomers as monomers, as prepared by ring opening metathesis polymerization (ROMP), reversible-addition fragmentation-chain transfer (RAFT) polymerization, and radical dead-end polymerization (DEP). In Aim 2, the stability of the capsule shell will be tuned by incorporation of dynamic covalent bonds; this will enable destruction or fusion of the capsule shells. In Aim 3, the capsule shell thickness will be minimized and the core fluid purity maximized by using reactive particle surfactants and thiol-ene chemistry. The capsule composition, morphology, thermal properties, permeability, and mechanical properties will be established. An unfunded collaboration with Prof. Burcu Gurkan will reveal the relationship between shell composition and permeability to gaseous CO2. An unfunded collaboration with Prof. George Pharr will support evaluation of individual capsules using micromanipulation techniques, producing force-displacement profiles. The scientific research is complemented by support of undergraduate and graduate researchers, as well as How-To Videos (HTVs) which demonstrate working principles and practical considerations for techniques used to characterize soft matter. .
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.