Redox-Driven Framework Expansion in Viologen COFs for Programmable Electrochemical Actuation
Year: 2026
Type: preprint
Abstract: Electrochemically driven ionic actuators operating at low voltages are promising for soft robotics, haptic interfaces, and adaptive systems. Yet, achieving fast response, large strain, long-term durability, and discrete stepwise actuation remains challenging. Here, we report a high-performance ion-driven actuator based on a viologen-based cationic covalent organic framework (V-COF), which integrates the ordered porosity and mechanical robustness of COFs with the rapid and reversible redox chemistry of viologen. The incorporation redox-active centers within the COF backbone enables redox-state-dependent lattice expansion and counterion diffusion under a small electrical bias, thereby translating molecular redox switching into controllable electrochemical actuation. The actuator exhibits a peak-to-peak bending strain of 1.86%, fast response time of 2.8 s, and cycling stability of 10,000 cycles with negligible degradation. Ex-situ and in-situ electrochemical analyses reveal that actuation is driven by reversible viologen redox reactions coupled with counterion diffusion through the ionically charged COF framework. This work establishes redox-active ionic COFs as a new class of actuator materials that bridge molecular-scale charge transfer and macroscopic motion, offering a new molecular design strategy for durable, low-voltage electrochemical actuation in soft robotic and smart-system applications.
Source: Research Square
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225331671