(4je) Engineering Surface-Active Nanoparticles System

Fluid-fluid interfaces have widespread industrial applications including foods, cosmetics, biosensing, lubricants, porous structures, drug delivery, coating, etc. In Pickering emulsions, solid particles stabilize the fluid-fluid interface, and their presence reduces the interfacial energy between the two fluids. In order to stabilize the oil/water interface with high efficiency, in my work, a type of amphiphilicity-adaptable graphene quantum dots (C-GQDs) was developed by a one-step bottom-up method. This fabricated C-GQDs could stabilize oil/water Pickering emulsions at an ultralow concentration. Their emulsion performance is reversible by adjusting pH values in aqueous solution. For expanding the practical applications of amphiphilic graphene quantum dots, I designed a type of zwitterionic graphene quantum dots (ZGQDs) by surface modification method to stabilize oil/water interface under harsh conditions, even under seawater environment. Moreover, the ZGQDs has dynamic interfacial assemble ability which made them have potential applied in controlled-release application.

The Pickering emulsion systems also have been used to template composite structures with improved functionalization, such as armored polymer particles and capsules. In order to introduce carbon-based nanomaterials into polymer matrix more efficiently to improve flame-retardant properties, I used surface-active GQDs to stabilize styrene-in-water Pickering emulsion as a template, and then do polymerization to give GQDs-armored particles with tunable flammability. The properties of prepared polymer composites could be tailored by controlling the nanoparticle concentration in aqueous phase. Next, in order to solve the instability issue of adding ionic liquids (ILs) in a coating system, I used to encapsulation of ILs to solve this problem. These ILs capsules were prepared by GQDs-based Pickering emulsion templated method, and were used as additive in a coating system directly. They would not lead to this system unstable, and improve the flame retardancy as well. Finally, I used these surface-active GQDs to decorated the 2D materials to improve the interfacial affinity between the additives and polymer matrix. The prepared polymer composites showed improved flame-retardant and mechanical properties with low loading of additives.

In summary, I focused on the development of varied functionalized GQDs to investigate their collective interfacial behavior, and exploit these nanomaterials in diverse applications including encapsulation, controlled-release, and fabricate polymer nanocomposites with improved properties.

Teaching Interests

During my Ph.D. studying, I have been working as a teaching assistant for four semesters. Based on this experience, I think a great teacher is to foster students’ motivation and curiosity. I found to encourage such curiosity is to root class in inquire-based learning. When students know these concepts and principles could be applied to practical problems, they will find them important and interesting. For my teaching session, I structured my courses with challenging and interesting questions at the beginning, and then introduce what concepts and principles related to these problems, and try to infuse students with a desire to know more. Achieving these objectives also requires making the students active participants as much as possible. For example, students would be given a project to discuss a practical problem and present it. During this process, they will better connect the fundamental concepts to practical problems. When students can draw and debate an idea, in addition to reading and hearing about it, they retain the information longer and can conceptualize the material for use in new contexts. Also, students could be more independent and critical thinking. By emphasizing both the importance and the pleasure of asking scientific questions, I hope to foster a thirst for knowledge that extends beyond the classroom. I hope to awaken a passion for learning in my students.