Chemical and Photochemical-Driven Dissipative Fe 3+ /Fe 2+ -Ion Cross-Linked Carboxymethyl Cellulose Gels Operating Under Aerobic Conditions: Applications for Transient Controlled Release and Mechanical Actuation.

A Fe 3+ -ion cross-linked carboxymethyl cellulose, Fe 3+ -CMC, redox-active gel exhibiting dissipative, transient stiffness properties is introduced. Chemical or photosensitized reduction of the higher-stiffness Fe 3+ -CMC to the lower-stiffness Fe 2+ -CMC gel, accompanied by the aerobic reoxidation of the Fe 2+ -CMC matrix, leads to the dissipative, transient stiffness, functional matrix. The light-induced, temporal, transient release of a load (Texas red dextran) and the light-triggered, transient mechanical bending of a poly- N -isopropylacrylamide (p-NIPAM)/Fe 3+ -CMC bilayer construct are introduced, thus demonstrating the potential use of the dissipative Fe 3+ -CMC gel for controlled drug release or soft robotic applications.