(7ca) Programmable Assembly and Deformation of Polymers and Networks

The main theme of my research was to understand the role that surface tension plays on sub-millimeter scale objects, especially on polymeric material systems, and how to utilize this phenomenon to assemble and deform such objects. My research addressed several phenomena of nano-and micro-sized polymeric soft objects at fluid interfaces. On the nano-scale, amphiphilic block copolymers were 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 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, and by controlling osmotic stresses to prepare multi-compartment emulsions and capsules. Next, thin temperature responsive polymer networks (i.e., hydrogel sheets) were 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 were then employed to drive the buckling of narrow, photo-crosslinked hydrogel ribbons. Further, I introduced a new concept of capillary assembly of soft hydrogel particles with programmed three-dimensional geometry. This offered opportunities to study correlations between elastic properties and surface tension, as well as to enabled unprecedented levels of control over inter-particle interactions, and therefore, higher-order assemblies.

The overall goal of my independent research program is to achieve programmable assembly and deformation of polymeric materials systems for applications ranging from biomedical devices to soft actuators by probing unexplored fundamental questions. The early stage of my independent research will involve 1) development of a new 4D microfabrication technique for programming internal heterogeneity in nanocomposite polymer networks, 2) exploration of a photo-switchable capillary assembly of shape programmed soft microparticles; and 3) analysis of bioenergetics at the single cell level by integrating a calorimetric sensor into the microfabrication-chip.

Teaching Interests:

I am excited to teach a wide range of existing courses in Chemical Engineering at the undergraduate and graduate levels. Moreover, I would be pleased to draw from my multi-disciplinary academic background to develop new courses related to polymer physics, polymeric material characterization, capillarity and wetting, and nano/micro-fabrication.