(6fq) Rational Design of Smart Soft Materials

Arrangement of colloidal building blocks to form structures is widely found in nature, the oldest and most profound being the internal structure of a living cell. It also has many important technological implications, ranging from the rheology and performance of paint formulations to the lightweight but strong materials on a military aircraft. There are pressing needs for a path to spatial organization of nano- and micro-scale building blocks with tunability and efficiency. I will develop an experimental program that creates functional soft matter that can be applied in energy-saving technology and in biotechnology. I propose to use my expertise in complex fluids and colloids and leverage fundamental work to advance the understanding of these systems, and identify scalable approaches that can lead to manufacturing technology. I will focus my efforts on dense suspensions, which are widely processed in myriad industries including food, personal care, energy, pharmaceutical, and construction material industries. The exploration in dense particle suspensions will follow three trajectories. The first aim of my work is to create innovative ways to form structures by an evaporative scheme. The second aim of this work is to modulate particle distribution by environmental stimuli. The third aim is to study how active colloids respond to obstacles and if patterns can be used to direct collective behaviors. The emphasis of my research will be to address the need of an alternative way to quantify and control parameters for objects to migrate and assemble, and their dynamic consequences in a complex environment.

Teaching Interests:

The role of the instructor is one that serves both as a source of knowledge and a facilitator for learning. Furthermore, I value the power of clear communication of highly technical knowledge. Therefore, I seek to create a classroom that promotes peer-learning, active learning, communication and learning beyond classroom. Learning outcomes results from a combination of stimulation and perception personal control, thus it is important to adopt course assignment to learner types. My goal for graduate education is to learn and evolve the projects with the graduate students’ input, so the project can develop in a direction that the student can feel a sense of ownership. I am well-prepared teach a wide range of courses offered in the undergraduate and graduate curriculum. Due to my research interests in soft matter and especially colloid science, I believe I can be most effective in teaching Fluid Transport, Thermodynamics, Heat and Mass Transport. I am also interested in developing a course in the area of Self-Assembly and Liquid crystals.

My background:

My Ph.D. work focused on directed colloid motion in a molded soft matter field. Using nematic liquid crystals (NLCs) as a model system, I designed boundary conditions that defined the orientation of the NLC molecules, known as the “director field”. NLC molecules are rod-shaped. They self-arrange in a manner roughly aligned with their neighbors as well as conform to boundary cues with the goal of minimizing distortion. In this way, they also control the assembly of the inclusions embedded in them. The inclusions can be particles, droplets, biomolecules, etc., with defined surface chemistry and independent bulk identity. By tuning the geometry of the bounding surface, I demonstrated the ability to position particles, plan trajectories, and template assembly.

As a postdoctoral scholar at the University of Delaware, I am learning what rheological signatures mean for material properties and processability. My current research effort centers on answering fundamental questions for a dense colloidal suspension, such as how friction affects maximum packing and flow behaviors. An industrial collaboration with Chemours has led me to study how components migrate and what structures are formed during drying in a multi-component system, using tools ranging from particle tracking, neutron scattering to oscillatory tests. These macroscopic characterization skills complement my Ph.D. training in microphysics nicely and provide good basis for my proposed research of exploring structural-property relationship to create smart soft materials.

Select Publications:

1. Y. Luo, T. Yao, F. Serra, D. A. Beller, and K. J. Stebe, “Deck the walls with anisotropic colloids in nematic liquid crystals", Langmuir, 2019, DOI: 10.1021/acs.langmuir.9b01811
2. Y. Luo, D. A. Beller, F. Serra, and K. J. Stebe, “Tunable colloid trajectories in nematic liquid crystals near wavy walls", Nat. Comm., 2018, 3841.
3. Y. Luo, F. Serra, and K. J. Stebe, “Experimental realization of the `lock-and-key' mechanism in liquid crystals", Soft Matter, 2016, 12, 6027-6032. (Front Cover: Soft Matter, 2016, 12, 6007-6008.)
4. Y. Luo, F. Serra, D. A. Beller, M. A. Gharbi, N. Li, S. Yang, R. D. Kamien, and K. J. Stebe, “Around the corner: Colloidal assembly and wiring in groovy nematic cells", Phys. Rev. E, 2016, 93, 032705.