Highly elastic layered carboxymethyl cellulose-based porous materials for sensing

Cellulose-based porous materials have attracted plenty of attention in advanced materials due to their satisfactory porosity, biocompatibility, and sustainability. However, pore collapse caused by hydrogen bonds between cellulose results in poor elasticity of materials, hindering their further applications. Furthermore, most cellulose-based porous materials use nanocellulose as basic materials, and require complicated production process. Therefore, exploiting highly elastic and low-cost cellulose-based porous materials by simple strategies remains a major challenge. Herein, a layered carboxymethyl cellulose (CMC)-based material was innovatively prepared with excellent elasticity and underwater stability based on the synergistic effect of directional freezing and Fe 3+ /ethanol/H 2 O immersing. Specifically, directional freezing makes the homogeneous CMC solution become the skeletons of layered and porous materials. And the coordination between Fe 3+ and CMC endows the material with excellent elasticity and underwater stability. Crucially, ethanol/H 2 O plays a significant role in regulating the structure and properties of this material. The material can withstand 1000 cycles compression tests (94.35 % height retention at 40 %), and can maintain compressive resilience when submerged underwater for more than 72 h. Surprisingly, the dry porous materials after being immersed in water still have good compressive resilience. This method can provide a potential material for future applications in pressure sensing and wearable devices.