Active and Janus Particles

Project Details

Project Lead
Ubaldo Cordova-Figueroa 
Project Manager
Ubaldo Cordova-Figueroa 
Project Members
Javan Cooper, Ronal De La Cruz-Araujo, Luis Y. Rivera-Rivera, Glenn Vidal  
University of Puerto Rico - Mayaguez, Department of Chemical Engineering  
Engineering Science and Engineering Physics (107) 
14.18 Materials Engineering 


This career development plan combines the PI’s expertise in low Reynolds number hydrodynamics and colloidal suspensions to study the emerging field of complex fluids based on “two-faced” Janus particles—particles which have two distinct sides—that depending on their surface functionality could lead to novel material properties and aggregation/self-ordering abilities or to autonomous behaviors using on-board chemical motors operating far from equilibrium. This proposal presents research and educational activities designed to elucidate important aspects of reconfigurable complex fluids—active materials that could change and relax their structure with minimum or no external intervention using as precursors Janus and catalytically-driven colloidal particles. The research efforts are divided in two main tasks. The first one focuses in studying the motion, rheology, and structural organization of Janus particle suspensions guided by a combination of fluid flows and external forces. Different behaviors are expected depending on the interparticle force between the ‘Janus’ faces of the particles (e.g., hard sphere, attractive, soft). The second research task aims at understanding collective motion of catalytically-driven Janus particle suspensions. A simple ‘colloidal’ approach to autonomous motion via chemical reactions will be used and implemented based on classic multicomponent diffusion and depletion flocculation theory. Simple elementary dynamic units operating with specific rules and exploiting chemotaxis will be proposed as ‘elements’ for future reconfigurable materials. These efforts will be accomplished by Brownian/Stokesian dynamics simulations and experiments with collaborating partners. The education and outreach components of the plan aim to involve the participation and enhance the education of Hispanics from the K-12 to the graduate level. At the graduate level, it is proposed to create a graduate course entitled “Particle Dynamics in Anisotropic Colloidal Suspensions”. At the undergraduate level, the tasks aim at the inclusion of emerging topics on colloidal hydrodynamics to an existing fluid mechanics course and the development and implementation of autonomously-moving Janus particles related modules for advanced multimedia presentation techniques in the classroom. In addition, the education activities include workshops to help students strengthen their communications skills and improve their preparation for the GRE. At the K-12 level, this proposal includes demonstrations and activities related to reconfigurable complex fluids that will be implemented through the Science on Wheels program.

Intellectual Merit

This work will provide a level of fundamental understanding of asymmetrically functionalized colloidal particles that has heretofore been missing, a lack which has thus far prevented the full development and use of Janus particle technologies–by leading to improved materials, sensors, and drug delivery. The measurement of their rheological behavior at different particle concentrations and flow conditions will broadly impact research on anisotropic colloids by providing a solid basis, basic tools, and knowledge that can be applied in the processing and use of these technologies. On the other hand, catalytically-driven motion of Janus particles will lead to the discovery of interesting material properties and behaviors, such as synthetic chemotaxis and predator-prey cooperative motions that are usually found in nature. The research plan aims at providing a necessary interrogation of catalytically-driven particle motion using Brownian/Stokesian dynamics simulations, particularly at conditions challenging to address experimentally (e.g., concentrated quantities, limited control volumes). The plan also proposes simple models of dynamic units based on catalytically-driven motion that could be exploited for the design and synthesis of reconfigurable complex fluids. The PI intends to use this work as an opportunity to build up a collaboration with other experts in this field. Educational activities for the creation of a graduate course in complex fluids from Janus and catalytically-driven particles, addition of cutting-edge colloidal hydrodynamics related topics into an undergraduate course, development of advanced multimedia colloids-related modules, development of K-12 education colloids-related modules and participation in early students recruitment for engineering careers will help to address future challenges in Chemical Engineering (ChE).

Broader Impacts

The proposed research plan will substantially impact several scientific and technological communities including colloids and complex fluids, microfluidics and physics of interphases. Above all, the main goal of this proposal is to teach and train underrepresented students in topics related to colloidal sciences and engineering. By carrying out the proposed research at the University of Puerto Rico—Mayagu ̈ez (UPRM), the participation and education of students from underrepresented groups will be significantly enhanced. The UPRM ChE Department serves over 650 Hispanic undergraduate students, the largest Hispanic chemical engineers producer in the US, 70% of which are female. There are also 37 PhD students, half of which are Hispanic US citizens. The research and educational activities presented in this proposal were designed with the UPRM strategic plan in mind. The efforts will also help the UPRM’s ChE program to implement aggressively research and education initiatives in colloidal hydrodynamics, engineering materials, and transport phenomena. The dissemination of results through peer reviewed journals, conferences, and online will disperse the information into the community.

Scale of Use

A set of simulations on entire systems will be run and for each I'll need 30 days to do that. It could take longer depending on the size of our suspension.