This proposal is a research plan for using theory and simulation to analyze and extend the inspace 1, 2, 3, and 3+ investigations of the self-assembly of magnetically responsive nanoparticles in a…

This is a research grant awarded by the National Aeronautics and Space Administration (NASA) to the Massachusetts Institute of Technology (MIT) to analyze and extend the InSPACE 1, 2, 3, and 3+ experiments on the self-assembly of magnetically responsive nanoparticles in a time-varying magnetic field. The $199,650 grant aims to re-evaluate the InSPACE data using new insights on out-of-equilibrium self-assembly, and to develop and validate a computational model of the nanoparticle self-assembly process that can facilitate the design of rapid nanomaterial syntheses. This research builds upon MIT's prior work on the InSPACE experiments and leverages the university's expertise in GPU-accelerated discrete element simulations to gain new insights from the microgravity data. The grant does not have a set-aside designation.

This proposal is a research plan for using theory and simulation to analyze and extend the inspace 1, 2, 3, and 3+ investigations of the self-assembly of magnetically responsive nanoparticles in a time-varying magnetic field. The original work found that selfassembly was greatly accelerated by utilizing a simple open-loop control scheme of the magnetic interactions. This methodology offers one solution to the difficult engineering challenge of developing scalable and cost-effective fabrication methods for structured nanomaterials with proven applications in optoelectronics, energy storage and harvesting, biological sensing, 3D printing, and highperformance coatings. However, because of limited spatial and temporal resolution in the experiments, detailed analysis of the selfassembled structures was impossible. A deeper understanding of out-of-equilibrium self-assembly demonstrated in the inspace suite is needed before IT can be leveraged to design processes that rapidly produce high quality nanomaterials. The proposed work has two main objectives. First, we will take advantage of insights developed since the inspace experiments for other out-of-equilibrium assemblies to RE-evaluate the inspace data in the PSI system. This will reveal new results that the original inspace team was unable to obtain. Second, we will use the inspace data in the PSI system to develop and validate a computational model of nanoparticle self-assembly in time-varying fields and use that model to extend the investigation of toggled magnetic field assembly beyond the parameter space explored in the experimental suite. This will aid in developing a predictive theoretical framework for dynamic self-assembly that can facilitate design of rapid nanomaterial syntheses. The work will utilize GPU-accelerated discrete element simulations of particle self-assembly driven by magnetic fields with detailed models of the magnetic and hydrodynamic interactions among the particles. The PI s, laboratory has recently developed new algorithms for modeling these interactions that have accelerated simulations by roughly a factor of 100 times. Consequently, discrete element simulations of the hierarchical self-assemblies observed in the inspace experiments are possible. The video micrographs from inspace are of limited spatial and temporal resolution, therefore, simulations capable of resolving the particle structure and dynamics on a local scale while replicating structure and growth kinetics on larger length scales and longer time scales provide addition insight into the inspace data. The ability to translate inspace microgravity data for the many-bodied, dynamic interactions among self-assembling particles into well-validated models for the same experiments will enable simulations to predict and then design dynamic self-assembly processes terrestrially as well as during continued space operations. The PI s laboratory has already demonstrated a predictive framework for other types of toggled self-assembly and is currently developing theories for the inspace assembly that can be used to predict the outcome and quantify the robustness of dynamical self-assembly processes. Incorporation of microgravity data into this theory is essential for testing its predictive capability. The PI was part of the original inspace 2 team as a post-doctoral scholar at the university of delaware before starting as an assistant professor at MIT. He is first author of the two published papers on inspace experiments and is intimately familiar with the project. He has also published several papers extending toggled self-assembly to ground experiments and to simulations of new systems. One MIT graduate student, zachary sherman, currently completing a PH. D. Focused on toggled self-assembly processes will assist in the research. Their extensive experience makes the investigators uniquely qualified to RE-examine and extend the inspace analysis.