Three-Dimensional Printing of Cytocompatible, Thermally Conductive Hexagonal Boron Nitride Nanocomposites

Hexagonal boron nitride (hBN) is a thermally conductive yet electrically insulating two-dimensional layered nanomaterial that has attracted significant attention as a dielectric for high-performance electronics in addition to playing a central role in thermal management applications. Here, we report a high-content hBN-polymer nanocomposite ink, which can be 3D printed to form mechanically robust, self-supporting constructs. In particular, hBN is dispersed in poly­(lactic-<i>co</i>-glycolic acid) and 3D printed at room temperature through an extrusion process to form complex architectures. These constructs can be 3D printed with a composition of up to 60% vol hBN (solids content) while maintaining high mechanical flexibility and stretchability. The presence of hBN within the matrix results in enhanced thermal conductivity (up to 2.1 W K^–1 m^–1) directly after 3D printing with minimal postprocessing steps, suggesting utility in thermal management applications. Furthermore, the constructs show high levels of cytocompatibility, making them suitable for use in the field of printed bioelectronics

Combustion-Assisted Photonic Annealing of Printable Graphene Inks via Exothermic Binders

High-throughput and low-temperature processing of high-performance nanomaterial inks is an important technical challenge for large-area, flexible printed electronics. In this report, we demonstrate nitrocellulose as an exothermic binder for photonic annealing of conductive graphene inks, leveraging the rapid decomposition kinetics and built-in energy of nitrocellulose to enable versatile process integration. This strategy results in superlative electrical properties that are comparable to extended thermal annealing at 350 °C, using a pulsed light process that is compatible with thermally sensitive substrates. The resulting porous microstructure and broad liquid-phase patterning compatibility are exploited for printed graphene microsupercapacitors on paper-based substrates

Enhanced Conductivity, Adhesion, and Environmental Stability of Printed Graphene Inks with Nitrocellulose

Recent developments in liquid-phase processing of carbon nanomaterials have established graphene as a promising candidate for printed electronics. Of great importance in the ink formulation is the stabilizer, which has to provide excellent dispersion stability and tunability in the liquid state, and also decompose into chemical moieties that promote high electrical conductivity and robust mechanical and environmental stability. Here we demonstrate the promise of nitrocellulose as a synergistic polymer stabilizer for graphene inks. Graphene processed with nitrocellulose is formulated into inks with viscosities ranging over 4 orders of magnitude for compatibility with a wide range of deposition methods. Following thermal treatment, the graphene/nitrocellulose films offer high electrical conductivity of ∼40 000 S/m, along with mechanical flexibility. Moreover, in contrast to state-of-the-art graphene inks based on ethyl cellulose, the nitrocellulose residue offers superior mechanical and environmental stability as assessed by a suite of stress tests, including the Scotch tape test, a water sonication test, and an 85/85 damp heat test. By exploring the fundamental chemistry underlying these macroscopic benefits, we provide insight into binder selection for functional nanomaterial inks while producing a high-performance graphene ink with strong potential for printed and flexible electronics