The goal of our research is to engineer polymer-based nanostructures for energy conversion, energy storage, 2D nanoelectronics and drug delivery.

Energy Storage

We are interested in developing polymer-based electrolytes for batteries with sufficient conductivity to power a portable device.  Currently, liquid or gel electrolytes are used in rechargeable lithium-ion batteries.  Replacing the liquid with a solid polymer would eliminate the heavy, rigid casing encapsulating the electrolyte; however, lithium transport (quantified by the ionic conductivity) is too slow through the polymer host.  The lithium ion mobility is facilitated by the segmental motion of the polymer in the amorphous domains, and there is recent evidence demonstrating fast lithium ion transport through crystalline regions where ions travel through polymer channels.  The channels provide a direct route for ion transport.  Increasing the number and alignment of these channels to improve ion mobility will require controlling the nanoscale morphology.

2D Nanoelectronic Devices

Electrons are used to store and transfer information in electronic systems.  In a capacitor, the absence or presence of charge at a surface can represent binary information.  In an integrated circuit, performance is determined in part by how quickly electrons move through the conductive materials. In order to develop smaller and faster future electronic devices, materials are needed that can store more electrons per unit area, and transport larger currents at a faster rate.  We replace the traditional gate dielectric with an ionically conductive polymer electrolyte, and the traditional substrate with graphene, in an attempt to improve charge carrier density and mobility.  The concept of modulating electrons via ions in a polymer could be applicable to a wide range of electronic devices. 

Drug Delivery

Our interests extend to materials for bio-applications, where control over the nanoscale structure and dynamics of biocompatible polymers will lead to advanced materials for drug delivery.  One such material is poly(N-isopropylacylamide) [PNIPAAM], a thermo-responsive polymer characterized by a lower critical solution temperature [LCST] at 32ºC. The brush is extended and hydrophilic below the LCST, and collapsed and hydrophobic above. A more comprehensive understanding of the molecular-level structure and dynamics must be achieved to optimize variables such as drug loading and delivery rate.

Techniques and Collaborators

Our efforts require a wide variety of experimental techniques, both at Notre Dame and at National Laboratories, such as the NIST Center for Neutron Research.  We use neutron scattering to study polymers because neutrons can provide information about structure and dynamics on the molecular level.  Our interdisciplinary work involves collaborations with faculty from the Department of Chemistry and Biochemistry, the Department of Chemical and Biomolecular Engineering, and the Department of Electrical Engineering.

Funding

Semiconductor Research Corporation (SRC)

The Defense Advanced Research Projects Agency (DARPA)

The U.S. Army TARDEC