Year: 2023
Type: article
Abstract: Little experimentally explored and understood are the complex dynamics of microstructure formation by ice‐templating when aqueous solutions or slurries are directionally solidified (freeze cast) into cellular solids. With synchrotron‐based, time‐resolved X‐ray tomoscopy it is possible to study in situ under well‐defined conditions the anisotropic, partially faceted growth of ice crystals in aqueous systems. Obtaining one full tomogram per second for ≈270 s with a spatial resolution of 6 µm, it is possible to capture with minimal X‐ray absorption, the freezing front in a 3% weight/volume (w/v) sucrose‐in‐water solution, which typically progresses at 5–30 µm s−1 for applied cooling rates of = 1–10 °C min−1. These time and length scales render X‐ray tomoscopy ideally suited to quantify in 3D ice crystal growth and templating phenomena that determine the performance‐defining hierarchical architecture of freeze‐cast materials: a complex pore morphology and “ridges”, “jellyfish cap”, and “tentacle”‐like secondary features, which decorate the cell walls.
Source: Advanced Functional Materials
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,250
Awards: Röntgentomoskopie in der Material und Prozesswissenschaft, G1885062978, G1920583378, G2421780581, G4466686350, DARTMOUTH S CONTRIBUTION TO THE TEAM EFFORT OF THE COLLABORATIVE NASA PROJECT ENTITLED STRUCTURE-PROPERTY-PROCESSING CORRELATIONS IN FREEZE-CAST BIOMIMETIC MATERIALS WILL BE TO INVESTIGATE AND DETERMINE WITH CUSTOM-DESIGNED FREEZING STAGES ANALYTICAL TOOLS AND CONTRIBUTIONS TO THE MODELING EFFORT THE KINETICS OF THE ICE-PHASE GROWTH AND THE MECHANISMS BY WHICH THE GROWING ICE-CRYSTALS THUS ICE PHASE TEMPLATES THE POLYMER PHASE DURING ITS TRANSITION FROM A SOLUTION TO A GLASSY SOLID. THE WATER-BASED SYSTEM WILL BE COMPARED WITH MODEL SYSTEMS SUCH AS THAT OF TBA-WATER: (I) WITH LIGHT MICROSCOPY PERPENDICULAR TO THE MOVING FREEZING FRONT WE WISH TO OBSERVE THE FORMATION OF MULLINS- SEKERKA INSTABILITIES AND THEIR SUBSEQUENT REORGANIZATION INTO AN ARRAY OF CELLS OR DENDRITES AS A FUNCTION OF POLYMER CONCENTRATION AND COOLING RATES WHICH IS EQUAL TO THE PRODUCT OF VELOCITY AND THERMAL GRADIENT IN DIRECTIONAL SOLIDIFICATION; (II) WITH CONFOCAL MICROSCOPY PARALLEL TO THE FREEZING FRONT WE WISH TO OBSERVE AND DETERMINE UNDER WHICH EXACT PROCESSING CONDITIONS SUCH AS POLYMER CONCENTRATION AND COOLING RATE THE DIFFERENT STRUCTURES FORM ON EARTH IN PREPARATION OF EXPERIMENTS USING THE REFURBISHED PFMI IN SPACE. FINALLY THE RESULTS OF THE EXPERIMENTAL AND THEORETICAL WORK WILL BE TRANSLATED INTO STRUCTURE-PROPERTY-PROCESSING CORRELATIONS FOR HIGHLY POROUS FREEZE-CAST MATERIALS (POLYMER CERAMIC METAL AND COMPOSITE) MADE ON EARTH SO THAT THEY CAN BE APPLIED IN THE DEVELOPMENT OF NEW AND IMPROVED FREEZE-CAST MATERIALS THAT ARE STRONG TOUGH AND LIGHTWEIGHT AND CAN BE CUSTOM-DESIGNED FOR A GIVEN APPLICATION. THE WORK EFFORT WILL PARALLEL THE FUNDING AND PHASE IN DURING YEARS 1 AND 2., G6671322778
OpenAlex ID: W4386022592