Azobenzene-Encoded Polymerizable Deep Eutectic Solvent Networks for Counteranion-Programmed Intelligent and Architected Ionotronic Elastomers

Soft ionic elastomers that integrate programmable ion transport, mechanical adaptability, self-healing, and additive manufacturability remain difficult to achieve due to the complexity of conventional multi-component systems. Here, we report a solvent-free azobenzene-functionalized polymerizable deep eutectic solvent elastomer (Azo-PDES) platform that enables counteranion-programmed adaptive behaviors within a chemically integrated ionic network. The system is constructed by copolymerizing a low loading of polymerizable azobenzene ionic liquid (AzoIL) comonomers into an acrylic acid/choline chloride (AA/ChCl)-based deep eutectic network, eliminating physically blended additives while maintaining network homogeneity and processability. Two counteranion-defined systems, AzoBr PDES and AzoTFSI PDES, reveal that counteranion selection governs supramolecular organization, viscoelastic dissipation, and photo-regulated ion transport. Under UV irradiation, Br⁻-containing networks exhibit increased impedance through ion-trapping interactions, whereas TFSI⁻-containing networks display enhanced ionic conductivity due to disruption of microphase-separated ionic domains and increased ion mobility. AzoTFSI PDES further demonstrates enhanced toughness, dynamic energy dissipation, and superior self-healing efficiency arising from reversible hard-domain reinforcement. The homogeneous low-viscosity precursor also enables high-resolution DLP 3D printing without additional photoabsorbent dyes by leveraging the intrinsic light-filtering effect of azobenzene units. The printed architectures exhibit self-healing, shape-memory-enabled 4D transformation, and reversible acid/base vapor-responsive impedance switching. This work establishes counteranion engineering and chain-encoded ionic interactions as an effective molecular strategy for multifunctional ionotronic elastomers for soft robotics, wearable electronics, and programmable 4D systems.