Self-Foaming Metal-Organic Gels Based on Phytic Acid and Their Mechanical, Moldable, and Load-Bearing Properties.

A catalogue of metal-organic gels are synthesized from phytic acid (PA) and a diversity of metal ions (Fe3+ , Cr3+ , Al3+ , Ce3+ , Y3+ , Co2+ , Ni2+ , Mn2+ , Cu2+ , Zn2+ , Mg2+ ) upon heating at 80 °C. PA-M gels have various morphologies, including irregular granular (PA-Fe, PA-Al, PA-Ce, PA-Cr, PA-Ni, PA-Co), spongy (PA-Y), and hollow tremella-like (PA-Cu) morphologies. Interestingly for PA-Fe-1 : 4 (PA:Fe3+ =1 : 4) a large amount of gas is generated during the gelation process leading to a self-foaming gel. The PA-Fe-1 : 4 self-foaming gel shows reversible gel-sol phase transition. The gel is unusually weakened and transformed into a sol at room temperature, and the sol is reversed to gelation when heated again at 80 °C. PA-Fe-1 : 4 gel also shows shapeable and load-bearing properties, and it can bear up to 200 times of its weight, depending on the gas amount fixed in the foam gel and the aging time. This work provides a catalogue of self-foaming supramolecular gels with tunable properties based on naturally abundant resources.