Photocuring of nanoparticle-based coatings via near-infrared sensitized free radical and cationic photopolymerization

 
NIR-LEDs have attracted more and more interests among the research for application in photopolymerization particularly for uses in coatings. It possesses some benefits compared to UV initiated polymerization. The longer wavelength facilitates deeper penetration and offers therefore more possibilities for photocuring in systems comprising components absorbing in the UV and visible part. In this work, cyanines derived from heptamethines carrying a special conjugated pattern facilitate both initiation of free radical and cationic photopolymerization as combined with new high-power NIR-LEDs emitting either at 860nm or 870nm. Iodonium salt with new anion based on perfluoroaluminates functions as co-initiator. We report for the first time curing of epoxides comprising sol-gel forming materials based on functionalized silanes. The heat generated by the NIR-sensitizer uptakes a special function. It facilitates generation of initiating species such as radicals and conjugate acid for radical and cationic polymerization, respectively, based on a photonic process.