475702 Programmable Assembly and Deformation of Soft Matter

Sunday, November 13, 2016
Continental 4 & 5 (Hilton San Francisco Union Square)
Jinhye Bae, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA

Research Interests:

While surface tension generally plays a negligible role on macroscopic scales, it is often the dominant force on nanometer to micrometer length-scales. The main goal of my research is to understand the role that surface tension plays on sub-millimeter scale objects, especially on soft material systems, and how to utilize this phenomenon to assemble and deform such objects. My research addresses several phenomena of nano-and micro-sized objects at fluid interfaces. On the nano-scale, amphiphilic block copolymers are used to explore interfacial behaviors due to their enhanced stability, mechanical properties, and tunability compared to other interfacially active materials such as small molecule surfactants or lipids. I have investigated the tailoring of amphiphilic block copolymer assemblies through deformation at the oil/water interface by inducing interfacial instabilities to incorporate inorganic nanoparticles into micelles, or by controlling osmotic stresses to prepare multi-compartment emulsions and capsules. Next, thin temperature responsive hydrogel sheets are used to probe elastic properties, buckling instabilities and capillary attraction at the micro-scale. I exploited the competition between surface energy and elastic bending energy to quantitatively determine key elastic properties of thin films that are otherwise challenging to measure. Additionally, I found significant edge imperfections due to the finite resolution of photolithography by observing interfacial deformations. The edge imperfections are then employed to drive the buckling of narrow photo-crosslinked hydrogel ribbons. Further, I introduced a new concept of capillary assembly of soft hydrogel sheets with programmed three-dimensional geometry. This offers opportunities to study correlations between elastic properties and surface tension, as well as capillary interactions between soft materials that can be extended to more complex multi-polar interface deformations.

I plan to form a research group to pursue,

- New lithographic techniques for programming internal heterogeneity in nanocomposite soft materials and characterization of their mechanical properties and photothermal effects.

- Deformation of liquids by external stimuli for the development of energy conversion devices.

Teaching Interests:

I am interested in teaching courses in Chemical Engineering at the undergraduate and graduate levels, as well as developing courses in polymer science and fluid mechanics.

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