Adhesive, self-healing, conductive Janus gel with oil-water responsiveness

The anisotropic Janus gel shows more diverse characteristic and responsiveness due to its asymmetric chemical structure. Herein, the water/oil PDA-PAA/PBMA-PEHMA Janus gel was prepared by one-step polymerization of incompatible monomers. In this Janus gel, PDA-PAA layer possesses good adhesion effect and self-healing property attributing to the chemical bonds and the hydrogen bonds among DA, AA, or each other, and the π-π stacking of DA. The IPN structure of the water phase and the oil phase makes Janus gel have good mechanical properties. The above chemical and physical effects dissipate a large amount of energy when PDA-PAA/PBMA-PEHMA Janus gel is subjected to external forces, so it has excellent fatigue resistance. The hydrophilic PDA-PAA side and the lipophilic PBMA-PEHMA side show different swelling responses in the oil-water medium. The internal stress difference caused by this different swelling makes the Janus gel show curl toward different directions in different media. Then, conductivity media of NaCl added in PDA-PAA layer endows Janus gel with anisotropic conductivity. It is possible to judge the hydrophilic and hydrophobic properties of solution by monitoring the current change of conductive Janus gel. Conductive Janus gel can also be used to monitor human body motion and micro motion. This conductive/insulating Janus gel is suitable for flexible sensor used in harsh environment.