Hierarchical Porous Micro-Architected Particles via Micro-Continuous Liquid Interface Production of Lyotropic Liquid Crystal Templates

Hierarchical porous materials with well-defined porosity spanning multiple length scales are highly desirable for separation and catalytic applications, where efficient mass transport and a high surface-to-volume ratio are required. Conventional etching and self-templating approaches exhibit limited control over nanopore morphology and pore size. In addition, thin film fabrication through casting and molding techniques further inhibits the engineering of three-dimensional transport pathways. Here, we report an approach combining high-resolution continuous liquid interface production (CLIP) printing with a lyotropic liquid crystal (LLC)-guided soft-templating method to create open-cell micro-architected particles containing hierarchical porosity ranging from nanometer to micrometer length scales. Prior to photopolymerization, LLC precursor mixtures are characterized with small-angle X-ray scattering (SAXS), and their self-assembled bicontinuous and lamellar mixed mesophases with characteristic <i>d</i>-spacing values of 52–60 Å are observed. Post photopolymerization, SAXS confirms the successful retention of sub-nanometer structure, and further inspection with SEM reveals the emergence of organized, concentration-dependent nanoporosity with pore diameters of 172–409 nm driven by polymerization-induced microphase separation mechanism. The organized pores and their narrow pore size distribution are hypothesized to be guided by LLC amphiphilic molecular templating during photopolymerization. The approach combining high-resolution additive manufacturing and LLC soft-templating demonstrates the capability to create open-cell architected materials containing hierarchical porosity spanning subnanometer to micrometer length scales.