Polyzwitterionic Organohydrogel and Soft Composite with Tunable Sol-Gel Properties Enabling On-Demand Functionalization with Colloids.

While zwitterionic hydrogels and aq. polymers have already been used in, e.g., bio-related, environmental, and ionic transport-related applications, it is foreseen that their characteristic ability of zwitterions to bind functional particles combined with sol-gel transitions can allow emerging potential for responsive soft composites. Here, it is first shown that polyzwitterionic poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (PDMAPS), allows organohydrogelation upon adding dimethyl sulfoxide to its aqueous solution, inducing phase-separations to form physical cross-links. Density functional theory (DFT) analysis reveals solvent-polymer interactions that drive the organohydragelation. The organohydrogels exhibit ultrahigh stretchability (>2800%), quick self-adhesion, remoldability, and tunable viscoelasticity. By modulating solvent composition and integrating functional fillers, distinct sol- and gel-like states are achieved on-demand. In the sol-like state, titanium carbide nanosheets (MXenes)-incorporated PDMAPS soft composite enable mechano-tunable electromagnetic interference shielding via nanosheet reorientation under strain. In the gel-like regime, incorporation of magneticneodymium iron boron magnet (NdFeB) microparticles yields mechano-magneto-electric transducers for strain detection, dynamic haptic functionality, as demonstrated by Morse code encoding, and high durability in repeated compressive cycles. This work introduces a versatile organohydrogel platform with tunable viscoelastic properties, suitable for on-demand functionalized soft composites, suggesting new design principles for transducing, sensing, and soft robotics.