Mechanically Programmable Ionogels through a Dynamic Salting‐Out Strategy

Abstract

ABSTRACT Gels exhibiting mechanically programmable strength under ambient conditions are essential for advancing flexible electronic devices. Here, a mechanically programmable ionogel based on choline chloride and poly(acrylic acid) (ChCl‐PAA) is presented, with CaCl 2 being a key structural modulator. Using a dynamically controlled salting‐out strategy, a crystal‐domain–locking architecture is formed that enhances mechanical strength. The cooling rate governs the resulting microstructure and mechanical properties, rapid cooling at −20°C min −1 generates numerous defective CaCl 2 lattices, that effectively induce interpenetration of PAA chains via coordination and establish localized “crystal locks”, producing a rigid network (Young's modulus 448 ± 14.21 MPa). Conversely, a slow cooling at −2°C min −1 promotes the growth of large‐sized densely packed CaCl 2 crystals, reduces polymer–crystal coupling, and yields to phase‐separated morphologies. Accordingly, the slowly cooled ionogel exhibits a remarkably high elongation at break (687 ± 18%) and a markedly reduced Young's modulus (11.6 ± 1.15 MPa). Overall, this dynamically controlled salting‐out strategy enables reversible hierarchical modulus regulation range spanning four orders of magnitude. This capability supports applications in reprogrammable adaptive devices, humidity‐driven energy harvesters, rapid‐response fire alarms, and bistable sensors that switch between rigid and ductile states. These findings provide a versatile design strategy for adaptive polymer–inorganic hybrid systems with mechanically programmable strength, electrical conductivity, and multifunctional stimulus responsiveness.