Hierarchically Porous Ceramics via Direct Writing of Binary Colloidal Gel Foams

Abstract

Hierarchically porous ceramics with a high specific surface area and interconnected porosity may find potential application as particulate filters, catalyst supports, and battery electrodes. We report the design and programmable assembly of cellular ceramic architectures with controlled pore size, volume, and interconnectivity across multiple length scales via direct foam writing. Specifically, binary colloidal gel foams are created that contain entrained bubbles stabilized by the irreversible adsorption of attractive alumina and carbon (porogen) particles at their air–water interfaces. Composition effects on foam ink rheology and printing behavior are investigated. Sintered ceramic foams exhibited specific permeabilities that increased from 2 × 10–13 to 1 × 10–12 m2 and compressive strengths that decreased from 40 to 1 MPa, respectively, with increasing specific interfacial area. Using direct foam writing, 3D ceramic lattices composed of open-cell foam struts were fabricated with tailored mechanical properties and interconnected porosity across multiple length scales.

Injectable, Pore‐Forming, Perfusable Double‐Network Hydrogels Resilient to Extreme Biomechanical Stimulations

“…The measured pressure and volume were used to calculate the permeability of the gel according to Darcy's law $$q = -\frac{k}{\mu L}P$$. [ 52 ]…”

“…The fluid that passes through the hydrogel was collected and measured using the stopwatch and bucket method. The measured pressure and volume were used to calculate the permeability of the gel according to Darcy's law q = − k 𝜇L P. [52] Cell Culture: Immortalized hVFFs were cultured in Dulbecco's modified Eagle medium (DMEM, Corning) containing sodium pyruvate and supplemented with 10% fetal bovine serum, 1% penicillin/streptomycin, and 1% MEM nonessential amino acids. Cells were incubated at 37 °C, in a 5% CO 2 humidified atmosphere.…”

Optimizing Process Parameters of Direct Ink Writing for Dimensional Accuracy of Printed Layers

“…Recent studies [8][9][10] focused on inks preparation and rheological analyses as ink rheology plays the most critical role in extrusion process, shrinkage, shape fidelity and structural stability. Meanwhile, DIW process parameters concerned with the equipment considerably affect the parts' dimensional accuracy [11].…”

Colloidal co‐assembly of dual‐phased ceramic/metal particles toward lightweight, hierarchically structured, and mechanically robust alumina foam

“…With regard to particle-stabilized foams, ceramic particles are spontaneously assembled onto the liquid-gas interfaces after tuning their surface-wetting properties by utilizing amphiphilic molecules; thus, a colloidal foam structure can be formed after mechanical stirring. 8 Further research works have proven that the absorption of those amphiphilic molecules and the stability of foam structures are inherently related to surface properties of particles in suspension, such as zeta potential and rheological properties. 9,10 Until now, multiple single-phased particlestabilized foams, such as Al 2 O 3 , SiC, and Si 3 N 4 , have been successfully fabricated, 11 whereas in these cases their mechanical strength is only related to bonding between ceramic particles.…”