A team from Donghua University has engineered a groundbreaking hydrogel that transforms from rubbery softness to rigid armor in seconds when heated—and just as quickly reverts to its flexible state when cooled. Published in National Science Review , this “high-entropy” hydrogel addresses a long-standing bottleneck in thermal-responsive materials: slow recovery.
Why It Matters
Traditional thermal-stiffening hydrogels, which harden upon heating, often take over 30 minutes to soften again due to slow phase dissolution. This delay limits their use in real-time applications like impact-resistant wearables or soft robots. The new hydrogel slashes recovery time to 28 seconds while maintaining exceptional stiffness (760-fold modulus increase at 80°C).
The Science Behind the Speed
The key lies in a high-entropy phase-separation design. By incorporating hydrophilic acrylamide (AAm) units into a calcium acrylate polymer network, the team disrupted dense clusters of calcium-crosslinked chains. This created a disordered, porous structure that allows rapid water diffusion during cooling.
“Think of it like loosening tightly packed Lego blocks with marbles in between,” explains co-author Shengtong Sun. “The high-entropy topology lowers energy barriers, letting the material ‘melt’ back to softness almost instantly.”
Performance Highlights
Applications on the Horizon
The material’s rapid switching dynamics make it ideal for:
National Science Review
Experimental study