Additive Manufacturing of Porous Carbon

Personnel: Dr. Miralem Salihovic (Postdoctoral Scholar),

Traditional methods for preparing porous carbon, such as activation or templating, excel at generating nanoscale porosity (pore diameters < 50 nm), but the resulting materials are typically limited to simple monolithic shapes. Additive manufacturing via vat photopolymerization can produce complex nano- and micro-architected 3D shapes but the solid constituents are typically either fully dense or have porosity that's challenging to control. This project is focused on developing an approach that can simultaneously deliver high nanoporous surface area with an arbitrarily complex three-dimensional architecture in carbon. We begin with a photo-curable resin that is compatible with commercially available DLP/SLA printers and capable of being patterned into intricate lattices with features in the low-micron regime. A single post-printing carbonization step converts the polymer network into hierarchically porous carbon while preserving both the designed macroscopic geometry and a hierarchical porosity in the nanoscale. The resulting carbon materials display a simultaneously high specific surface area and precisely designed microscopic geometries. This combination makes the materials attractive for applications as high-performance energy-storage electrodes, catalyst supports that incorporate built-in flow channels, and multifunctional devices that require both the nanoscale surface area and a functionally designed 3D pattern. In summary, we introduce a rapid-prototyping route for hierarchically porous carbon and open the door for new possibilities in energy storage, catalysis, lightweight structures, and beyond.

AutoFab of Unprecedented Alloys and Structures: Automated characterization and design

Personnel: Yingjin Wang (Ph.D. student in Material Sicence), Pietro Toniolo (Ph.D. student in Mechanical Engineering), and Anna Wu (Ph.D. student in Material Science)

Collaboration with Professor Kaushik Bhattacharaya's Group (Caltech).

The capabilities of automated material fabrication and high-throughput characterization have attracted increasing attention for enabling faster materials screening and design. This project aims to develop a high throughput additive manufacturing technique that is amenable to control over microstructure and mechanical properties of metals. We build on our group's work in the CuxNi1-x system and will extend to complex multiphase alloys fabricated via HIAM (Hydrogel Infusion-based Additive Manufacturing), such as oxide-dispersion strengthened and dual-phase alloys. We developed an advanced nanomechanical setup with an in-situ module inside of an SEM chamber, with multi-sample functionality that enables automated mechanical measurements of sample arrays. We are conducting high-throughput experiments by fabricating and deforming micro-specimens of varied alloy compositions and treatments within a single HIAM build. Combined with advanced computations and machine learning, these systems allow us to investigate the interplay among fabrication processes, chemical composition, microstructure, and mechanical properties, providing new opportunities to accelerate materials discovery and optimization.

Novel Synthesis of Multimaterial Polymer Nanocomposites

Personnel: Kaleb Funk (Ph.D. student in Material Sicence),

Typical polymer nanocomposite materials are created through the combination of preformed nanostructures with a matrix precursor that forms around the reinforcements. One major drawback that these materials experience is inadequate interaction between the matrix and the interface of the reinforcement. Poor binding between matrix and reinforcing phases can prematurely induce deformation mechanisms that actually worsen the mechanical behavior of the overall composite. Additionally, due to the high surface areas among nanostructures, preventing agglomeration within the matrix and achieving proper dispersion can be extremely difficult at high loadings, worsening these effects. To improve these interfacial interactions and overall integration of the nanostructures in the polymer matrix, we introduce a DLP-based 3D printing technique to simultaneously form the nanostructures with the surrounding polymer matrix. By appropriately mixing the nanostructure precursor among the matrix monomers, we take advantage of the high dispersibility of the precursor as opposed to the formed nanostructures to prevent agglomeration. Formed nanostructures are also expected to achieve better matrix integration as well, due to the polymer chains growing with the nanostructures as opposed to around them. We expect the simultaneous formation of reinforcement and surrounding matrix to influence network connectivity and overall mechanical performance. By precisely tuning the timing of the formation events of the nanostructures in relation to the surround polymer matrix, we expect to uncover new deformation mechanisms within the polymer nanocomposites.