Entanglement-mediated bulk energy dissipation enables strong and tough UV-curable adhesives

Tough adhesives require efficient bulk energy dissipation, yet the molecular design principles for achieving this without sacrificing adhesion strength remain a challenge. Here, we report a chain-length regulation strategy for UV-curable acrylate adhesives, in which long polymer strands between cross-linking points generate effective entanglements, thereby promoting bulk energy dissipation during debonding. The resulting adhesives achieve exceptional adhesion strength (23.13 MPa) and ultrahigh adhesion toughness (36.77 kJ m^-2). Fracture measurements and digital image correlation show that the long-chain entangled network markedly increases bulk fracture energy by delocalizing crack-tip strain into an enlarged deformation process zone and retarding crack propagation. Chain-dynamics and chain-conformation analyses further confirm the role of entanglement by revealing a broader relaxation spectrum and a much larger releasable conformational length in the long-chain network that enhances bulk energy dissipation. We further demonstrate its application potential and excellent long-term environmental stability, together with a physics-informed prediction of long-term adhesion retention across practical service temperatures. These results establish chain-length regulation as an effective molecular design strategy for strong and tough adhesives.