The lightweight elastomer with fatigue resistance can meet the actual use needs of wearable electronic devices, flexible sensors and portable devices, and has attracted widespread attention in recent years. Considering the complexity of practical application environment, conductive gel with wide temperature range, high fatigue resistance and high sensitivity is one of the most promising materials. However, in order to meet the needs of good conductivity, these aerogels are usually composed of expensive conductive nanomaterials or involve high-temperature carbonization, and the preparation process is tedious and energy consumption is high. Therefore, it is necessary to develop a low-cost, sustainable, non carbon based elastic aerogel.

Based on this, the research team of Northeast Forestry University reported an ordered honeycomb aerogel composed of cellulose nanofibers (CNF) and silicon dioxide nanofibers (SiO2) interwoven and wound based on the dual fiber hybrid strategy, and polymerized polypyrrole in situ to make it electrically active, realizing the detection of extreme temperature resistance and human activity signals, which has broad application prospects in thermal insulation materials, strain sensors and other applications.

It is reported that this aerogel is prepared by the ice template method, which homogenizes and mixes cellulose nanofibers and electrospun silica nanofibers through a high-speed homogenizer, and then adds a certain amount of MTMS as the adhesive. The ice template method can help aerogels obtain honeycomb like microstructures, while the double network nanofibers intertwine with each other, which can further improve their mechanical strength and structural stability.

In the fatigue test, the aerogel has only slight plastic deformation (3.57% in the 100th cycle, 7.14% in the 1000th cycle), has excellent fatigue resistance, and maintains super elasticity and environmental adaptability under low temperature (liquid nitrogen) and liquid (ethanol) conditions.

As the addition of SiO2 nanofibers and MTMS can significantly improve the thermal stability of CNF based aerogels, combined with the ultra-high porosity of aerogels (99.37%), this material also has broad application prospects in the field of thermal insulation. The test results show that the surface temperature of CNF/SiO2 aerogel is kept at 45.4 ° C, only slightly higher than the initial temperature, and has excellent thermal insulation performance after being heated continuously for 1h on a 150 ° C heating platform.

Benefiting from the structural stability, fatigue resistance and environmental stability of CNF/SiO2 aerogel, PPy can be grown by simple in-situ polymerization to form a three-dimensional conductive network in the aerogel PPy@CNF /SiO2 aerogels show good linear compression sensitivity and high strain sensitivity, which are not only better than other cellulose based aerogels, but also higher than most reported carbon based aerogels. In addition, PPy@CNF /SiO2 aerogel can also accurately capture and record human motion signals and pulse, which is expected to be used in wearable electronic devices, electronic skin and human detection.