One‐Step Fabrication of Highly Asymmetrical Adhesive Hydrogel Integrated With Robust Adhesion and Ultralow Swelling

Developing asymmetric adhesive hydrogel simultaneously with the anti‐swelling capability for internal wound remains a great challenge. Herein, a facile one‐step approach was designed to prepare a versatile hydrogel patch with highly asymmetric adhesion between two sides (21 times), robust tissue adhesion of the bottom side (557.3 J/m 2 ), and ultra‐low swelling ratio (0.25). The asymmetric distribution of self‐assembled emulsion droplets within the precursor induces the anti‐adhesion of the top side yet strong adhesion of the bottom side. The incorporation of a hydrophobic crosslinker into the core of emulsion droplets endows the ultra‐low swelling of the hydrogel. This optimized hydrogel achieves high burst pressure even after being soaked in water, and effectively seals the defects of isolated organs under water. The vivo rat experiment confirms that this hydrogel not only can firmly adhere to the gastric defect but also address the postoperative adhesion issue. This work provides a simple yet effective strategy to prepare the high‐performance hydrogel for treating internal wound.