Anisotropic interparticle interactions in Janus colloidal suspensions offer enhanced tunability in their aggregation into various cluster sizes and morphologies, a feature particularly significant for magnetic Janus particles, where the magnetic dipole is shifted away from the center of mass toward the particle’s surface and can be externally controlled. To investigate the time-evolving cluster structures and gain valuable microstructural insights, we employ Brownian dynamics (BD) simulations, focusing on dilute suspensions where the fundamental building blocks of these materials are formed.
Using BD simulations, we calculate various structural and dynamic properties to construct a phase diagram that illustrates different cluster structures based on the dipolar shift and the dipolar coupling constant (the ratio of magnetic dipole-dipole interactions to Brownian motion).
Ubaldo M. Córdova-Figueroa,
University of Puerto Rico at Mayagüez
Each region in the phase diagram corresponds to distinct nucleation and growth behaviors, as well as the orientational ordering of dipoles within clusters. Furthermore, we examine the formation of these structures under shear flow, particularly in regions where shear competes with Brownian motion and magnetic interactions. Additionally, we conducted simulations on magnetic Janus particles exhibiting autonomous motion, where the final structure formation is governed by two competing mechanisms: one stabilizing clusters through magnetic interactions and another disrupting clusters due to self-propulsion at high speeds. We anticipate that the diversity of structures and dynamic behaviors found in these suspensions will be instrumental in developing new and reconfigurable soft materials for a wide range of applications.
Dr. Ubaldo M. Córdova-Figueroa holds a bachelor’s degree in chemical engineering from the University of Puerto Rico at Mayagüez (UPRM) and both a master’s and doctoral degree in chemical engineering from the California Institute of Technology, where he was advised by Prof. John F. Brady.
Currently, Dr. Córdova-Figueroa is a professor of chemical engineering and an adjunct professor in the bioengineering graduate program at UPRM. His research group specializes in theoretical soft matter and fluid mechanics, with a focus on reconfigurable and multifunctional soft materials, such as suspensions of anisotropic particles, active particles, liquid crystals, and Janus droplets.
He has served, and continues to serve, as PI and co-PI on projects funded by the NSF, NASA, EDA, and DoD, with awards totaling more than $20 million. Dr. Córdova-Figueroa has also received the NSF CAREER Award. Additionally, he is the former Executive Vice President for Academic Affairs and Research at the University of Puerto Rico, where he developed strategies that intersected academic innovation, administrative transformation, research, and entrepreneurship to promote student success.
He is the founder and CEO of Acerola Strategies, a subscription-first consulting firm that supports leaders and organizations in developing and implementing strategic action plans to achieve measurable success using principles of adaptive and complexity management. Since August 2019, Dr. Córdova-Figueroa has been a member of the board of directors of the Puerto Rico Science, Technology & Research Trust, an autonomous entity driving the transformation of Puerto Rico’s economy toward one centered on research and innovation.