Multi‐Responsive COF‐Enhanced Smart Actuator

Abstract Smart composite materials are attracting increasing attention for their novel stimulus‐response characteristics. Among them, Cellulose nanofibers (CNF)‐based smart composites are widely used due to their excellent properties. For enhancing the response rate and stability of CNF‐based smart composite actuator, a novel covalent organic framework (COF) nanoparticle is synthesized via molecular design to enhance CNF‐based multi‐responsive composite materials. COF‐TASA, characterized by a high specific surface area, exhibits the highest photothermal conversion efficiency of 79.9% for COF materials to date. A multi‐stimuli responsive actuator is prepared through the compounding of COF‐TASA, CNF, and polyvinylidene fluoride (PVDF). The smart membrane demonstrates a reversible ability to change shape when exposed to near‐infrared (NIR) light and humidity. This is caused by the asymmetric deformation of the COC and PVDF layers. Finally, the mechanism for the enhancement of the smart response rate of the system by COF‐TASA is successfully elucidated through experiments and molecular dynamics (MD) simulations, indicating that the introduction of COF forms ordered channels in the COC, greatly enhancing the specific surface area and the transport speed of water molecules. This COF‐enhanced smart actuator is anticipated to provide important solutions for smart control, smart detection, and environmental energy collection.