B.S., Massachusetts Institute of Technology, (2000)
PhD, University of Wisconsin-Madison, (2007)
Block copolymers, polymer self-assembly, nanostructured materials, advanced lithography and nanofabrication.
Directed self-assembly of block copolymers for nanolithography.
Block copolymers self-assembled in thin films form regular structures at the sub-50 nm scale, including lamellae, cylinders and spheres, that are suitable templates for patterning applications. This patterning approach, known as block copolymer lithography, has been used in the past to nanofabricate devices such as quantum dot arrays and photonic crystals that require a high-density of periodic features. In the near future, structures simultaneously patterned at varying densities and in more complex geometries will be required, for example in the critical layers of integrated circuits. Our research applies heterogeneous surfaces to direct the self-assembly of polymeric films into useful, device-oriented structures for advanced patterning applications. We focus on developing polymeric materials that self-assemble into novel structures, characterizing such structures in thin films and in the bulk, and demonstrating functional integrated circuits patterned using these approaches.
Polymer-polymer interfaces are often generated spontaneously through phase separation processes in copolymers or polymer blends, and dominate the structural, mechanical, optical, and transport properties of such systems. These interfaces are relatively soft/flexible and therefore their shape is influenced by the interface bending rigidity (a function of the Flory-Huggins parameter), capillary waves, and thermal fluctuations. We study, using experiments and simulations, the interfaces between lamellar block copolymer domains focusing upon their impact as line edge roughness in the resulting nanopatterns.
Designing porous membranes from self-assembled network morphologies.
Advancements in membrane technology and nanostructured materials will play a critical role in the development and improvement of alternative energy technologies. Fuel cell technologies, for example, may achieve enhanced hydrogen production, storage, and utilization with appropriately designed nanostructured membranes. We investigate the self-assembly of polymer materials into continuous network morphologies, specifically developing strategies for controlling organization of such structures at interfaces and in three dimensions. Our research also aims to functionalize and test such nanostructured membranes for a range of applications.