Bespoke Gold Foams via Xerogel Templating

Project Overview

Metal foams are critical materials for high-energy-density physics experiments; however, there is a gap in our ability to manufacture nanoporous metals between 50 mg/cm3 and 1000 mg/cm3 with controlled nanoporosity, composition, and geometry. One key potential application is foam-walled hohlraums for laser targets that have a simulated optimal density between 100 mg/cm3 and 1000 mg/cm3. Advanced catalytic materials with hierarchical, architected porosity are key materials in the energy and environmental security mission space, which would benefit from nanoporous metals with controlled mechanical properties, composition, and microstructure. This project focused on gold foams as both a key material of interest and a well-behaved model material.

The approach was to develop an etchable, 3D printable nanoporous template with induced hierarchical porosity (1 mm thick samples desired). To realize larger samples a flow cell concept was developed and demonstrated uniform gold deposition into 4 mm nanoporous templates. This concept is a potential route for realizing macroscopic nanoporous objects at the desired densities.

An additional technical advance is the development of a 3D printable, transparent, intrinsically nanoporous polyimide aerogel with demonstrated strategies for inducing hierarchical closed- or open-pore architectures. Pore morphology is critical to optimizing mass transport in nanoporous materials for catalytic and energy-storage applications.

Mission Impact

This project focused on producing a fieldable mid-density gold-foam target by the end of FY23 and is expected to lead to novel hohlraum designs, furthering the DOE mission of advancing high-energy-density science. 3D printable, intrinsically nanoporous polyimide resins have potential applications as advanced catalytic membranes in support of the DOE's energy and environmental security mission with further development.

Publications, Presentations, and Patents

Mettry, M. Y. et al., 2022. "Transparent Polyimide Aerogels: Controlled Porosity via Minimizing the Phase Separation." ACS Applied Polymer Materials 4, 11: 8065-8072. https://doi.org/10.1021/acsapm.2c00957.