Nanomanufacturing by Heterogeneous Aggregation and Magnetic Alignment of Multi-Functional Nanoparticles

North Carolina State University, Raleigh NC

Investigators

Abstract

Multifunctional nanoparticles are of great interest because of their ability to simultaneously respond to multiple stimuli and exhibit connection between components. This award supports fundamental theoretical and experimental research on heterogeneous aggregation, or heteroaggregation, as a method for nanomanufacturing of core/satellite nanoparticles consisting of a core nanorod covered by a shell of many smaller satellite nanoparticles of a different composition. Heteroaggregation is a simple approach, based on mixing solvents with different properties to drive the assembly of pre-synthesized nanoparticles. This method is readily scalable to large volumes. Use of externally applied magnetic fields to align nanorod cores coated with magnetic satellite nanoparticles has potential applications in advanced pigments, mechanical strengthening of composite materials, and biomedical imaging. Advances in these applications impact national prosperity and security. This research enables new capabilities for nanomanufacturing by developing methods and strategies for conducting, modeling, and characterizing heteroaggregation processes and magnetic alignment that can be applied to other systems spanning a wide range of material compositions and length scales. Education and outreach activities are planned to educate students and teachers in nanoscience and nanotechnology and engage women and under-represented minority students in research and nanomanufacturing training. Nanomanufacturing of multifunctional nanoparticles remains challenging due to limitations in seeded growth and self-assembly processes. This research aims to overcome these challenges by creating a theoretical and experimental framework for heteroaggregation. Controlling the solvent conditions and the compositions, sizes, and concentrations of the core and satellite nanoparticles drives heteroaggregation in forming uniform core/satellite nanoparticles, while avoiding homoaggregation of either the core or the satellite nanoparticles. Molecular dynamics simulations are performed to predict the conditions for heteroaggregation of core/satellite nanoparticles, which comprehensively guide experiments and interpret results. For selected systems, the scalability of heteroaggregation for nanomanufacturing is investigated in both batch processes and continuous microfluidics. The understanding of magnetic alignment of core/satellite nanorods is achieved through molecular dynamics simulations and experimental verification. Dipolar interactions among magnetic satellite nanoparticles are predicted to provide torque for magnetic alignment, and it is important to establish the conditions under which sufficient torque is generated to drive magnetic alignment. Magnetic alignment imparts new properties for the heteroaggregates such as magneto-optical, polarization and microrheology, and elastic modulus for nanocomposites. 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.