Fabricating Ceramic Nanostructures with Ductile-like Compression Behavior via Rapid Self-Assembly of Block Copolymer and Preceramic Polymer Blends

Abstract

Here, we report a rapid and scalable process for the fabrication of nanostructured silicon carbide (SiC)-based ceramics displaying mechanical metamaterial properties. These novel mesoporous structures are achieved through patterning at the nanoscale via block copolymer (BCP) self-assembly. In this facile process, a blend of preceramic polymer (PCP) and BCP is dissolved in warm solvent, cast, and quickly solidified as an organogel composed of a 3D micelle network. Significantly, these materials rapidly self-assemble and do not necessitate the annealing steps that are typically required for block copolymer self-assembly. The PCP nanostructure of the films is thermally stable and maintained through pyrolytic soft template removal and conversion to ceramic. Exploration of PCP, BCP, and PMMA homopolymer blends resulted in the discovery of a cocontinuous wormlike micelle phase, which after pyrolysis translated into a ceramic nanocoral-like structure with a network of high-aspect-ratio ceramic struts punctuated with mesopores. In situ nanomechanical compression testing reveals ductile-like deformation, complete strain recovery up to 14% strain, and enhanced energy absorption over bulk ceramics. The confluence of rapid self-assembly, affordability, and mechanical metamaterial properties offered by this system surmounts many of the challenges associated with producing materials nanostructured over large areas. As such, these materials hold considerable promise for a variety of applications including energy storage, filtration, and catalytic materials.