Li Bowen, Zhu Xinyi, Xu Chaoqun, Yu Juan, Fan Yimin
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
Carbohydr Polym. 2024 Jul 1;335:122108. doi: 10.1016/j.carbpol.2024.122108. Epub 2024 Mar 29.
Cellulose nanofiber was an ideal candidate for humidity actuators based on its wide availability, biocompatibility and excellent hydrophilicity. However, conventional cellulose nanofiber-based actuators faced challenges like poor water resistance, flexibility, and sensitivity. Herein, water-resistant, flexible, and highly sensitive cross-linked cellulose nanofibers (CCNF) single-layer humidity actuators with remarkable reversible humidity responsiveness were prepared by combining the green click chemistry modification and intercalation modulated plasticization (IMP). The incorporation of phenyl ring and the crosslinked network structure in CCNF films contributed to its improved water resistance and mechanical properties (with a stress increased from 85.9 ± 3.1 MPa to 141.2 ± 21.5 MPa). SEM analysis confirmed enhanced interlaminar sliding properties facilitated by IMP. This resulted in increased flexibility and toughness of CCNF films, with a strain of 11.5 % and toughness of 9.9 MJ/m. These improvements efficiently enhanced humidity sensitivity for cellulose nanofiber, with a 4.8-fold increase in bending curvature and a response time of only 3.4 ± 0.1 s. Finally, the good humidity sensitivity of modified CNF can be easily imparted to carbon nanotubes (CNTs) via simple self-assembly method, thus leading to a high-performance humidity-responsive actuator. The click chemistry modification and IMP offer a new avenue to fabricate tough, reversible and highly sensitive humidity actuator based on cellulose nanofiber.
纤维素纳米纤维因其广泛的可用性、生物相容性和出色的亲水性，是湿度传感器的理想候选材料。然而，传统的基于纤维素纳米纤维的传感器面临着诸如耐水性差、柔韧性和灵敏度低等挑战。在此，通过结合绿色点击化学修饰和插层调制增塑（IMP），制备了具有显著可逆湿度响应性的耐水、柔性且高灵敏度的交联纤维素纳米纤维（CCNF）单层湿度传感器。CCNF薄膜中苯环的引入和交联网络结构有助于提高其耐水性和机械性能（应力从85.9±3.1MPa增加到141.2±21.5MPa）。扫描电子显微镜分析证实了IMP促进了层间滑动性能的增强。这导致CCNF薄膜的柔韧性和韧性增加，应变达到11.5%，韧性为9.9MJ/m。这些改进有效地提高了纤维素纳米纤维的湿度灵敏度，弯曲曲率增加了4.8倍，响应时间仅为3.4±0.1秒。最后，通过简单的自组装方法，可以轻松地将改性CNF的良好湿度敏感性赋予碳纳米管（CNT），从而得到高性能的湿度响应传感器。点击化学修饰和IMP为制备基于纤维素纳米纤维的坚韧、可逆且高灵敏度的湿度传感器提供了一条新途径。
