Highly transparent, room-temperature self-healing UV-curable coating based on the synergistic effects of disulfide and hydrogen bonds

UV-curable SAP coating achieves 98.2% scratch healing at 25 °C within 4 h. • SAP-C exhibited transmittance > 91%, haze < 1%, Grade 0 adhesion, and hardness 2H. • SAP-C combines flexible chains, dynamic disulfide bonds, and dense hydrogen bonds. • Both Dynamic bonds and flexible chains are essential for RT self-healing of coating. • SAP-C with a low T g is the dominant factor for its RT self-healing. The rapid development of flexible optoelectronic devices has increased demand for protective coatings that combine optical transparency, mechanical durability, strong substrate adhesion, and autonomous self-healing at room temperature (RT). To address this challenge, we designed a flexible polypropylene glycol-based dual-dynamic oligomer (SAP) containing reversible disulfide bonds and hydrogen-bonding units, together with three structurally distinct control networks (BDP-C, SAT-C, and SPIH-C) that served as boundary-condition probes to systematically vary dynamic bond exchange, crosslinking density, and segmental rigidity. SAP-C exhibited a low glass transition temperature (T g  = 6.68 °C), a characteristic stress-relaxation time (τ) of 29.4 s at 25 °C, and a scratch-closure efficiency of 98.2% within 4 h at RT. Comparative results showed that rapid local network relaxation alone does not guarantee macroscopic self-healing: although SPIH-C exhibited a shorter τ than SAP-C, its scratch-healing performance was poorer, whereas the excessive crosslinking density of SAT-C strongly suppressed network rearrangement and healing. These findings distinguish local stress dissipation from long-range interfacial reconstruction and indicate that efficient RT self-healing requires dynamic exchange sites coupled with sufficient segmental mobility to enable effective re-contact and reconstruction of the damaged interfaces. Meanwhile, SAP-C achieved an optical transmittance ≥ 91%, a haze ≤ 1%, Grade 0 adhesion to both PET and glass, 2H pencil hardness, and a Taber abrasion loss of only 12.1 mg after 500 cycles. This study establishes a structure–network rearrangement–macroscopic healing relationship in UV-curable coatings, providing a mechanistic basis for designing transparent protective coatings with autonomous RT self-healing capability. Download: Download high-res image (240KB) Download: Download full-size image