Heat-loving hydrogel hardens as temperature rises

Inspired by thermophile organisms that rely on the heat of hot springs and thermal vents for survival, the material was created by immersing a polyacrylic acid gel in a calcium acetate aqueous solution. At room temperature, the resulting substance has the consistency of a regular hydrogel, but as the heat rises it separates into a polymer dense phase and a polymer sparse phase.

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When the temperature hits around 60°C, the dense phase undergoes significant dehydration which strengthens ionic bonds and hydrophobic interactions between polymer molecules, causing the material to rapidly transform from a soft, transparent hydrogel to a rigid, opaque plastic. According to the research, published in Advanced Materials, this rigid plastic is 1,800 times stiffer, 80 times stronger, and 20 times tougher than the original hydrogel.