Cationic Photocuring of Vinyl Ether Polyurethanes toward Resilient and Transparent Optical Adhesives

Conventional radical-based UV-curable acrylic pressure-sensitive adhesives (PSAs) are severely limited by oxygen inhibition, leading to incomplete surface curing and polymerization shrinkage. To address these issues, we report a cationic photopolymerization strategy based on vinyl ether-functionalized polyurethanes for fabricating high-performance optically clear PSAs. A vinyl ether-terminated prepolymer (PUE-BDO) was synthesized by the chain extension of an isocyanate-terminated polyurethane with 1,4-butanediol, followed by end-capping with 4-hydroxybutyl vinyl ether (HBVE). A difunctional vinyl ether monomer (IP-VE) was prepared from HBVE and isophorone diisocyanate. By systematically adjusting the ratios of PUE-BDO, IP-VE, and triethylene glycol divinyl ether (DVE-3), we achieved precise control over the cross-linking network and viscoelastic properties of the materials. The resulting PSAs exhibited exceptional optical clarity, with 99% transmittance and