Thermally insulating and electroactive cellular nanocellulose composite cryogels from hybrid nanofiber networks
Yi Hu, Meilian Cao, Jianing Xu, Xueying Liu, Jiqing Lu, Jie Yan, Siqi Huan, Guangping Han, Long Bai, Wanli Cheng, Orlando J. Rojas
Abstract
Cellulose-based xerogels, cryogels and aerogels have been proposed to deliver the functions required by next-generation wearable electronics and energy materials. However, such systems often lack functionality and present limited mechanical resilience. Herein, we introduce a simple strategy to synthesize high-performance cryogels that combine cellulose and silica nanofibers that form ice-templated cellular architectures. Specifically, dual networks are produced by incorporating organic (cellulose) and inorganic (silica) nanofibers to form highly interconnected and vertically-aligned channels. Hence, ultralight structures (7.37 mg cm−3 in density and porosity of 99.37%) are produced with high mechanical strength, compressibility (dimensional recovery of up to 90%) and fatigue resistance (1000 loading cycles) along with low thermal conductivity (29.65 mW m−1K−1). Electrical responsiveness is supplemented by in situ polymerization of pyrrole, ensuing operation in a wide load range (0–18 kPa with sensitivity of 6.63 kPa−1 during > 1000 cycles). The obtained thermal insulating and electroactive materials are demonstrated for operation under extreme conditions (solvent and temperature). Overall, our dual network system provides a universal, multifunctional platform that can substitute state-of-the-art carbonized or carbon-based light-weight materials.