Redox-Active Polymers as Platforms for Adaptive and Trainable Soft Materials

Electrochemically active polymers offer powerful routes for imparting adaptive mechanical and transport properties into soft materials. In this talk, I will highlight how leveraging the redox chemistry of disulfide-based macromolecules enables new classes of responsive and trainable polymer systems. First, I will introduce poly(glycidyl methacrylate) microparticles crosslinked with bis(5-amino-1,3,4-thiadiazol-2-yl) disulfide moieties (DS-RAPs), which exhibit reversible redox-triggered actuation. We demonstrate that under reductive potentials, and with modest convective flow, DS-RAPs can actively detach from and "self-clean" fouled electrode surfaces, illustrating a particle-level design strategy for intrinsically maintainable electrochemical interfaces. Second, inspired by biological muscle hypertrophy, we further develop suspensions of electrochemically active disulfide-crosslinked particles that undergo stimulus-induced swelling and jamming. Application of electrochemical stimulus drives particle expansion into a jammed state, stiffening the suspension by orders of magnitude. Importantly, repeated electrochemical "training," especially when paired with small-amplitude oscillatory shear, produces persistent structural memory whose magnitude and stability depend on the training protocol. This memory can be selectively erased at high shear strains matching those used during training. Together, these results highlight a new family of polymer materials whose mechanical and transport properties can be dynamically tuned, trained, and reset through synergistic chemical and mechanical pathways, demonstrating that electrochemical stimuli can trigger jamming and enable controllable training and memory effects.