Holey Graphene Mesh from Solvent-Free Manufacturing and Composites Thereof

This invention is for scalable methods that allows preparation of bulk quantities of holey nanocarbons with holes ranging from a few to over 100 nm in diameter. The first method uses metal particles as a catalyst (silver, copper, e.g.) and offers a wider range of hole diameter. The second method is free of catalysts altogether and offers more rapid processing in a single step with minimal product work-up requirements and does not require solvents, catalysts, flammable gases, additional chemical agents, or electrolysis. The process requires only commercially available materials and standard laboratory equipment; and, it is scalable. Properties that can be controlled include: surface area, pore volume, mechanical properties, electrical conductivity, and thermal conductivity.

NASA and the US Army Engineer Research and Development Center (ERDC) co-developed advanced graphene materials designed to improve the filtration rate of spacecraft water contaminants which could significantly extend the service life of existing media filtration beds. Traditional granulated activated carbon (GAC) media is characterized by having a polymodal pore structure and contains micro-, meso-, and macropores that trap and contain contaminants. By using the referenced method to add graphene nanoparticles to an existing GAC filtering substrate, additional filtering can be achieved due to graphene’s mostly mesoporous nature. A high-level overview of the graphene loading process is thus: The unloaded graphene nanoparticles are mixed with a water-based graphene suspension for an extended time at room temperature. This “graphene bath” process is repeated several times before the now graphene-loaded (up to ~ 1% by mass) filtration media is dried and prepared for packing into a filter cartridge. The graphene suspension used during the loading process may be reused multiple times, reducing consumables in the process. Laboratory testing has shown a 40x improvement in contaminant removal per mass of the absorbent (i.e., graphene) over the state of the art (granulated activated carbon) at lower loading rates, suggesting significant promise of the treated filter media posing a potential solution to the demands of an entire mission lifecycle. Potential commercial applications for this graphene loading method may lay in four distinct market segments that rely on filtration media beds (outside of aerospace): industrial filtration such as ultra-pure water refining for the semiconductor industry, commercial filtration, residential filtration, and filtration-as-a-service. Graphene nano-particles’ tunable pore sizing, in conjunction with this loading method, could offer tailored filtration boosting for existing water filter substrates. The Graphene Loading Method for Water Filtration Media has a technology readiness level (TRL) 4 (Component and/or breadboard validation in laboratory environment), and it is now available for patent licensing. Please note that NASA does not manufacture products itself for commercial sale.

To overcome the challenges of conventional molding, researchers at NASA Glenn have developed a rapid prototyping approach for three-dimensional printing of polymer aerogels using deposition into a viscous, sacrificial support medium. The sacrificial support stabilizes the aerogel deposition, allowing precise layer-by-layer construction of self-supporting aerogel networks that would otherwise be unprintable in air. Following printing and gelation of the polymer network, the printed structure is gently removed from the sacrificial medium, yielding a freestanding aerogel precursor with high shape fidelity. This method decouples printability from intrinsic material viscosity and enables rapid iteration of aerogel geometries, offering a scalable pathway for additive manufacturing of ultra-lightweight, architected polymer aerogels with tailored geometries, while retaining microstructural, mechanical, and thermal properties. The method involves: 1. Forming a solution comprised of a polymer precursor, cross-linker, solvent, and catalyst to create a dilute polymer solution. 2. 3D printing the polymer precursor directly into the sacrificial support medium. 3. Following printing and network formation, the structure is removed from the sacrificial medium through a low-stress extraction process, yielding a freestanding polymer aerogel precursor that retains the as-printed geometry with high fidelity. The sacrificial medium functions as a temporary, conformal support matrix that stabilizes each deposited droplet or filament in situ, enabling freeform construction of aerogel. This strategy enables the fabrication of highly porous, interconnected networks with controlled feature resolution across multiple length scales, while maintaining the intrinsic low density and high surface area required for aerogel performance.

In traditional batteries with liquid electrolytes, e.g., lithium-ion, each battery cell must be individually sealed, packaged, and electrically connected to other cells in the pack. The cells in solid-state batteries on the other hand may be stacked on top of one another with only a separation layer in between, called a bipolar plate. These bipolar plates or membranes if thin enough must be electrochemically inert to the electrode and electrolyte materials while providing electrical connectivity between the individual cells. Here, NASA has combined advances in the preparation of carbon nanomaterials and solid-state batteries to create extremely lightweight bipolar plates and membranes. These bipolar membranes will enable high energy density solid-state batteries unachievable with typical bipolar plate materials like stainless steel, aluminum, aluminum-copper, or conductive ceramics. The carbon bipolar membranes may be fabricated in multiple ways including but not limited to directly compressing carbon powders onto an electrode-electrolyte stack or separately making a film of the carbon material and dry pressing the film between other battery layers. The new bipolar membranes have been demonstrated in high energy density solid-state batteries in coin and pouch cells. The carbon bipolar membranes are at technology readiness level TRL-4 (Component and or breadboard validation in laboratory environment)and are available for patent licensing.

The technology portfolio spans several methods for dispersion and processing of CNTs in polymer resins and composites. CNT/resin systems with high dispersion and long-term stability are provided by three general approaches. One method relies on mechanical dispersion by sonication simultaneous with partial polymerization to increase the resin viscosity to maintain dispersion and enable further polymer processing of the CNT blend into films and other articles. Another approach relies on what is termed donor acceptor bonding, which essentially is a dipole bond created on the CNT/resin interface to maintain dispersion and stability of the CNT/resin blend. This dispersion method also provides advantages in mechanical properties of processed composites due to the interface characteristics. A range of polymer types can be used, including polymethyl methacrylate, polyimide, polyethylene, and others. An additional dry blending approach provides advantages for a variety of thermoplastic and thermoset systems. Use of ball mill mixing achieves effective blending and dispersion of the CNT, even at high loadings. Further processing steps using injection molding or similar melt processing methods have yielded CNT/ polymer composites with a range of useful electronic, optical, and mechanical properties.