Dual bio-inspired strong and humidity-responsive composite cellulose nanofibril papers.

Cellulose nanofibril (CNF) papers have attracted great interests in recent years because of their attractive performance and the green resource of CNF. However, the thermomechanical properties of CNF papers are insufficient for some sophisticated applications that require higher mechanical properties or smart functionalities. In this paper, a dual bio-inspired strategy is reported to improve the thermal and mechanical properties, as well as the humidity-responsive behavior of CNF papers. CNF is first functionalized by mussel-inspired polydopamine, and then, composite CNF papers with nacre-like layered structure are fabricated by the incorporation of graphene oxide (GO). In addition, Fe³⁺ is introduced into the composite CNF papers to provide coordination cross-linking for each components. By such compositional and structural design, the composite papers demonstrate significantly enhanced mechanical properties as compared to original CNF paper. Meanwhile, the improved thermal stability and humidity-responsiveness are also demonstrated. This study is expected to provide alternative approach for high-performance and functional CNF materials. [ABSTRACT FROM AUTHOR]