Phase‐Separated Patch With Dual‐Functional Interfaces Enables Antiadhesive Tension‐Free Hernia Repair

The clinical demand for novel patches that prevent adhesion and enable tension-free repair continues to motivate biomaterials research. Inspired by the Janus nature of the peritoneum, we developed a phase-separated patch with distinct functional interfaces through a straightforward layer‑by‑layer molding process. By fusing two sol layers with different polyvinyl alcohol (PVA)-polyethylene glycol (PEG)-dimethyl sulfoxide (DMSO)-water ratios, in situ phase separation and PEG‑induced plasticization are achieved within the forming PVA hydrogel patch. The as-produced patch features (i) a highly porous, soft surface to support healing of abdominal wall defects, and (ii) a dense, stiff surface to prevent visceral adhesion, and both functions have been confirmed in in vitro and in vivo evaluations. The patch demonstrates robust mechanical properties (0.73 MPa ultimate strength, 275% elongation) and exceptional anti-swelling behaviors (-4.96% after immersion in 0.01 m PBS for 21 days), characteristics that are highly favored in clinical prognosis. Moreover, this patch is physically crosslinked and can be completely dissolved and recovered using only hot water. Such a phase-separated patch is convenient in fabrication, environmentally friendly, biocompatible, and effective in antiadhesive tension-free hernia repair, and thus should be valued as a promising candidate for next-generation non-woven hernia patch.