双重动态共价键交联纳米纤维素导电水凝胶及其柔性传感器

自愈合导电水凝胶因其良好的自愈合性能与导电性能，在柔性可穿戴设备中具有巨大的应用前景。以4-甲酰基苯硼酸（Bn）交联聚乙烯醇（PVA）和聚乙烯亚胺（PEI）构建基于硼酸酯键和亚胺键的双重动态交联水凝胶网络，引入聚吡咯修饰的纤维素纳米纤维（PPy@CNF）构建了具有良好自愈合和导电性的PBP-PPy@CNF纳米复合水凝胶。结果表明，当PPy@CNF的质量分数为0.8%时，水凝胶的力学性能最佳，其最大应力可达6.65kPa，断裂拉伸应变可达2080%，电导率为2174μS/m。基于该水凝胶的电阻式传感器具有良好的稳定性和重复性，在应变检测范围0~800%内，灵敏因子GF可分为三个线性响应区域，分别是0~200%（GF₁=2.82）、200%~600%（GF₂=7.15）和600%~800%（GF₃=12.85），该传感器能有效检测人体不同部位的运动，可应用于可穿戴传感设备。

Double dynamic covalent bond crosslinked nano-cellulose conductive hydrogel for a flexible sensor

Self-healing conductive hydrogels have great potential applications in flexible wearable devices because of their good self-healing properties and electrical conductivity. A double dynamic cross-linked hydrogel network based on borate ester bond and imine bond was synthesized via cross-linking polyvinyl alcohol (PVA) and polyethylenimine (PEI) with 4-formylbenzoboric acid (Bn). Then, PPy@CNF (grafted polypyrrole (PPy) on the surface of CNF) was incorporated to construct PBP-PPy@CNF nanocomposite hydrogels with good self-healing and electrical conductivity. The results indicated that when the content of PPy@CNF was 0.8wt%, the mechanical properties of the hydrogel were the best. The maximum stress and the fracture tensile strain can be up to 6.65kPa and 2080%, respectively with electrical conductivity of 2174μS/m. In the strain range of 0—800%,the gauge factor GF can be divided into three linear response regions,namely 0—200% (GF₁=2.82), 200%—600% (GF₂=7.15) and 600%—800% (GF₃=12.85). The strain sensors integrated by PBP-PPy@CNF hydrogel with good stability and repeatability can efficiently identify and monitor the various human motions,showing promising applications in the field of wearable sensing devices. This study provided a new way for the design of conductive hydrogel and broadens the application of nanocellulose in sensor field.