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#A novel 3D printing approach enables the creation of ultra-strong, dense #Metal and ceramic structures by growing materials inside hydrogels, offering new possibilities for advanced manufacturing. @epfl_en @advmater https://t.co/wdspBXyL0E

Check it out here:

Our review on Ice Lithography is now out in Adv. Funct. Mater.! Excellent work led by @anpan_han and his team at DTU. Glad to have played a small role in this :) Link in reply.

Bonus 2: I wrote my first grant on this idea. It was rejected. A reviewer didn't think it would work, another reviewer didn't think it would be able to significantly improve part quality. I'm glad we persisted.

Bonus 1: We were able to (loosely) track the growth of particles within our hydrogels. It gave us some beautiful images. We called this one "Sauron"

This tremendous effort was led by Yiming Ji, a PhD student in my group. Incredible persistence and great mastery of materials characterization. Truly a tour de force. The work was supported by Ying Hong, a former postdoc, and Dhruv Bhandari, a former intern now at Cornell. (9/9)

We also spent a lot of time calculating the densities of parts made using other metal-salt printing approaches. (cf. SI) Density is vastly underreported in our field, so we hope that this will encourage others to report it moving forward. Don't just focus on shrinkage! (8/9)

To show the material, size, and geometric versatility of this technology, we made a variety of metal parts and even hard magnets! (7/9)

Some numbers to put this in context: Average shrinkage values today: ~80% Average density values today: ~50% Our work: Shrinkage values: ~20-40% Density values: ~90% These parts are now much closer to the qualities needed for practical use. (6/9)

With such high metal loadings, we were able to reduce the polymer-to-metal shrinkage while simultaneously increasing part density. These materials now significantly outperform the state of the art (including our previous work!) (5/9)

Using this idea, we were able to grow nanoparticles within our hydrogels and convert them into high filler wt% composites (up to 80% of metal!) (4/9)

The challenge is and was metal loading. How do you go beyond the metal ion-equilibrium limit of the hydrogel? Our trick: convert the metal ions into metal particles and reinfuse the hydrogel with more metal ions (3/9)

A while ago, we pioneered a hydrogel-based method of fabricating ceramics and metals. (Saccone et al. Nature. 2022). A persistent challenge we faced was that the hydrogel-to-metal process was always accompanied by high shrinkages and material porosity. Not ideal! (2/9)

And our second paper is now out in Advanced Materials! https://t.co/YMYF0cYJry tldr: we use a repeated infusion-precipitation process to enable the fabrication of ceramics and metals with low shrinkages and high material densities (1/9) A little 🧵

We have some new openings in the group! (PhD student + Research intern) Details can be found here:

We've come so far in 60 years. Majulah Singapura! 🇸🇬

@Ji_Yiming29 @EnzeSu @xolo3D And now it's back to twitter hibernation. See ya when we drop the next paper or when something crazy happens. 🫡

That's about the gist of it! We think this can be a general approach to making composites when transparency during printing is necessary. More to come :) This work was led by @Ji_Yiming29 and supported by @EnzeSu. Thanks to @xolo3D for supporting this work! (8/8)

Finally, we can use this approach to make multimaterial structures as well. By controlling where infusion and/or precipitation happens, you can spatially control the formation of the filler. Here, we only grew the iron oxide on the top surface of the spring! (7/8)