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Thermally recoverable UV coating protects foldable display glass
A newly developed UV-curable polyurethane acrylate coating combines high modulus, toughness and thermal recovery capability to reinforce ultra-thin glass for foldable displays. The system offers a scalable PET-free alternative and withstands 200,000 folding cycles without delamination.
Ultra-thin glass (UTG) has established itself as a key substrate for foldable displays, but its inherent brittleness requires effective protective coatings to guarantee mechanical durability. Conventional polyethylene terephthalate (PET) protective layers show clear limitations under repeated folding, prompting the search for alternative material systems. A recent study introduces a tri-functional polyetheramine-based polyurethane acrylate (PEUA) UV-curable resin designed for direct application to UTG.
The resin was synthesised from hydroxyethyl acrylate (HEA), isophorone diisocyanate (IPDI) and polyetheramine. The cured coating maintained an optical transparency of over 92 % at 550 nm and reached a storage modulus of approximately 2.18 GPa, combined with a thermal decomposition onset (T5 %) of around 252 °C and a glass transition temperature of about 140 °C.
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Mechanical performance and thermal recovery of stress whitening
Mechanical testing showed that a 40 µm-thick PEUA layer increased the pen-drop failure height of UTG by 16 cm compared with the uncoated reference. The failure mode also changed from catastrophic radial cracking to localised, non-propagating indentation. In folding tests, the coated UTG endured 200,000 inward folding cycles at a bending radius of 3 mm without creasing or delamination. Under extreme folding conditions at a radius of 1.5 mm, stress whitening did occur, but optical clarity was fully restored through a brief thermal treatment.
The authors attribute the balanced performance to the optimised cross-linked network, in which rigid IPDI segments deliver structural stiffness while the flexible polyetheramine chains dissipate viscoelastic energy. This design addresses the long-standing trade-off between rigidity and toughness in UTG protective materials. The work presents a scalable, PET-free coating concept for high-performance protection of next-generation foldable electronics, with potential to improve both device reliability and user experience.
Source: Shi, G. et al., High-modulus and toughened polyurethane acrylate coating with thermal recovery capability for the mechanical reinforcement of ultra-thin glass. Progress in Organic Coatings (2026). https://doi.org/10.1016/j.porgcoat.2026.110253
