Superabsorbent 'Gel Sheets' with Fabric-Like Flexibility—A 'Better Picker-Upper' for Water and Blood

Materials that can absorb aqueous liquids have evolved along two parallel tracks for the past millennia. On the one hand, there are flexible, foldable materials like cloth or paper towels that are convenient to use but not very absorbent. On the other hand, we have superabsorbent polymer hydrogels (SAPs) with the ability to absorb more than 100x their weight in water, but in dry form these become fragile solids. Here, for the first time, we report the synthesis of <b>‘gel sheets’</b> that combine the above properties in the same material. The sheets are prepared at macroscopic sizes (e.g., 10 x10 cm) by foam-templating (polymerizing monomers around the bubbles of a foam), followed by addition of a plasticizer (glycerol) and ambient drying. The dried sheets are macroporous (pore sizes ~ 240 µm, porosity &gt; 80%), flexible, soft, and robust; they can be folded, rolled up, and cut with scissors to desired sizes, much like fabrics. At the same time, they can rapidly absorb substantial amounts of water, like hydrogels. Remarkably, these sheets <b><i>expand as they absorb water</i></b>, which is unlike any sponges or absorbents made from fabric or paper. The sheets are also able to absorb viscous liquids like blood as well as viscoelastic, non-Newtonian liquids like polymer or surfactant solutions. Absorbed liquids are retained within the gel sheet when it is lifted up whereas with typical commercial controls, excess liquid drips down. Due to their unique properties, these gel sheets could be useful in cleaning up spilled liquids in a variety of locations, including homes, labs, and hospitals. They could also be useful tools for absorbing biological fluids during surgeries or other medical procedures.