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Reversible adhesion in UV-cured coatings via disulfide bonds
Researchers have developed UV-cured coatings that combine strong adhesion with on-demand removability by combining substrate silanisation with dynamic disulfide chemistry. The photoinitiator-free system offers new possibilities for recyclable coatings and sustainable packaging solutions.
A research team has introduced a strategy for controlling the adhesion of photocured coatings by combining substrate silanisation with dynamic disulfide interfacial chemistry. The approach yields photoinitiator-free coatings that simultaneously deliver strong adhesion and controlled removability by exploiting the reversible nature of disulfide bonds. A disulfide-functionalised polyurethane diacrylate (DSPDA) served as the photocurable monomer, while bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) was used to introduce disulfide functionalities at the substrate interface via silanisation.
The DSPDA monomer underwent efficient self-photopolymerisation under UV irradiation without any photoinitiator, reaching a conversion of approximately 95 % within 150 s. Coating performance was systematically evaluated on glass, polyethylene terephthalate (PET) and polyethylene (PE) substrates. No adhesion was observed on non-functionalised substrates, confirming the essential role of interfacial silanisation.
Thermal activation enhances interfacial bonding
Post-curing thermal treatment activated disulfide metathesis, promoting bond rearrangement at the interface and enhancing coating adhesion. Optimised conditions achieved adhesion levels of 4 A for silanised glass (150 °C, 60 min) and 5 A for PET and PE substrates (90 °C, 30 min). Lap shear testing confirmed the improvement in interfacial strength resulting from thermally activated disulfide exchange.
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On-demand removal via targeted stimuli
The reversible nature of the disulfide bonds enabled controlled coating removal under specific stimuli. Complete detachment was achieved on glass at 140 °C under acidic conditions (pH 3), while PET and PE coatings were removed using glutathione (GSH) as a reducing agent under ultrasonic agitation. The results demonstrate that disulfide-based dynamic covalent networks, combined with substrate silanisation, offer an effective route for designing UV-cured coatings with reversible adhesion and recyclability, opening new opportunities for sustainable surface technologies and circular material design, particularly for multilayer packaging systems where end-of-life separation remains a persistent challenge.
Source: Akram, A. et al., Tunable adhesion of UV-cured coatings via silanization-enabled dynamic disulfide interfacial bonding. Progress in Organic Coatings (2026). https://doi.org/10.1016/j.porgcoat.2026.110210
