The goal of this CAREER award is to develop an integrated program of education and research focused on the creation of novel metamaterials, which are advanced composite materials that exhibit properties not usually found in naturally occurring materials. Metamaterials are often created by adding filler particles to a substrate, such as a polymeric material. If the size, shape, and orientation of the filler particles can be precisely controlled, then macroscopic properties of the material such as its strength or stiffness, can be tailored in novel ways. This project will use magnetic fields to control filler particles, such as magnetic microdisks that have been used in preliminary experiments. The project will develop theoretical models to help identify novel strategies for engineering composite materials. The experiments and theory will test the hypothesis that metamaterials can be designed on the sub-micron length scale by controlling the alignment time of submicron filler particles and the solidification of the composite. Results from the project could help advance additive manufacturing by finding ways to vary properties spatially through a composite material. The project will include development of new modules and hands-on activities for K-12 and college participants in a new course titled, "Exploring the Magic of Physics via Hands-on Service Learning." Furthermore, the research team will leverage the use of 3D printing capabilities in their laboratory to develop workshops on 3D modeling and printing for high-school students and teachers.
Composite metamaterials will be fabricated by aligning two-dimensional magnetic particles, i.e., disks, in Newtonian fluids while controlling the center of mass distribution of the particles. The size, shape, orientation, buoyancy, susceptibility, and concentration of the particles are each expected to influence alignment dynamics and the formation of disruptions, such as the particle chaining, which could lead to unwanted heterogeneity in the material. The experiments will involve the use of new kind of magnetic tweezer apparatus for investigating alignment using a rotating magnetic field. Two-particle interactions under various magnetic field conditions will be examined. Then, the rheological properties of colloidal suspensions will be measured to determine influences of particle shape and orientation. Strategies will be identified for magnetically aligning filler particles while preventing chain formation. Then, an apparatus will be developed to systematically analyze control parameters during alignment and polymerization of bulk anisotropic composites. Continuum-based theoretical descriptions for particle motions in viscous fluids in the presence of body forces will help interpret experimental data, provide insight into the design of filler particles, and guide precision engineering of advanced composites. Nanocomposites with precisely aligned fillers will offer new opportunities for innovation in creating advanced biomaterial, optical, electromagnetic, and membrane technologies.
