The influence of tiny amount fluorine-containing acrylate on kinetics, morphology and properties free-radical/cationic hybrid UV-cured coatings

A series of UV-curable, fluorine-containing mixtures were prepared by adding different micro amounts of small molecular weight fluorine-containing acrylate dodecafluoroheptyl methacrylate (DFMA) to an interpenetrating polymer network system composed of cycloaliphatic polyurethane acrylate, trimethylolpropane triacrylate, cycloaliphatic epoxy resin, free-radical photoinitiator Irgacure 754 and cationic photoinitiator Irgacure 250 with a weight ratio of 15:15:65:1:4. Hybrid coatings with different addition amounts of DFMA (0.2, 0.4, 0.6 wt.%) were cured from the mixtures by UV-initiated free-radical/cationic dual curing technique. Final reactant conversions of the hybrid UV-cured coatings were all for 97% with different DFMA content, as evaluated by conversion profiles. The microstructures and morphologies were characterized by fourier transform infrared spectrophotometer and scanning electron microscopic measurements. Thermal, mechanical and surface properties of the hybrid UV-cured coatings were investigated. Thermo-gravimetric analysis revealed that fluorine incorporation into the cross-linked network structure resulted in higher thermal stability. The mechanical properties almost invariant before DFMA content increased to 0.6 wt.%. The surface properties of hybrid UV-cured coatings had an obvious improvement. These researches showed that micro amounts of small molecular weight fluorine-containing acrylate could greatly influence the microstructure and morphologies of the dual-cured system and therefore improve overall performance of the UV-cured coating.