Network of cyano-p-aramid nanofibres creates ultrastiff and water-rich hydrospongels

초록

The structure-property paradox of biological tissues, in which water-rich porous structures efficiently transfer mass while remaining highly mechanically stiff, remains unsolved. Although hydrogel/sponge hybridization is the key to understanding this phenomenon, material incompatibility makes this a challenging task. Here we describe hydrogel/sponge hybrids (hydrospongels) that behave as both ultrastiff water-rich gels and reversibly squeezable sponges. The self-organizing network of cyano-p-aramid nanofibres holds approximately 5,000 times more water than its solid content. Hydrospongels, even at a water concentration exceeding 90wt%, are hard as cartilage with an elastic modulus of 50-80MPa, and are 10-1,000 times stiffer than typical hydrogels. They endure a compressive strain above 85% through poroelastic relaxation and hydrothermal pressure at 120 degrees C. This performance is produced by amphiphilic surfaces, high rigidity and an interfibrillar, interaction-driven percolating network of nanofibres. These features can inspire the development of future biofunctional materials. Biological tissues are extremely water rich but remain mechanically stiff, behaviour that is difficult to recapitulate in synthetic materials. Here the authors design a hydrogel/sponge hybrid material driven by a self-organized network of cyano-p-aramid nanofibres that combines these properties for biofunctional materials.

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