Effects of carboxymethylation and TEMPO oxidation on the reversibility properties of cellulose-based pH-responsive actuators

Abstract Cellulose-based actuators hold great promise for diverse applications, including soft robotics, biomedicine, and electronics. Achieving reversible motion is crucial to design high performance bio-based actuators. In this study, we explore the impact of carboxymethylation and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation on the reversible performance of cellulose-based pH-responsive actuators. Both methods introduce negatively charged groups onto the surface of cellulose fibers, enabling increased water uptake at high pH. However, comparative analyses revealed structural differences, guiding the design of reversible actuators. Carboxymethylated CNFs (CMCNFs) displayed enhanced water uptake and pH sensitivity, attributed to their less cohesive structure. Actuation and reversibility tests on bilayer films validated these findings. This research advances the understanding of cellulose functionalization for tailored actuation, contributing to the development of programmable materials for multiple applications.