Synthesis of multifunctional silsesquioxane nanoparticles with hydroxyl and polymerizable groups for UV-curable hybrid coating

UV-curable multifunctional silsesquioxane-based nanoparticles (SQ-NPs) with hydroxyl and polymerizable groups were synthesized by hydrolytic co-condensation of two hydroxyl group-containing triethoxysilane (HEA-TES) molecules derived from 2-hydroxyethyl acrylate with hydrophobic triethoxysilanes carrying vinyl, methacryloyl, and methyl groups. The co-condensation in methanol in the presence of an acidic catalyst quantitatively produced multifunctional SQ-NPs with relatively narrow size distributions (average particle diameter < 5 nm) without gelation. The hydrophilic/hydrophobic balance, solubility, crosslinkable vinyl content, and thermal stability of the multifunctional SQ-NPs could be manipulated by changing the composition of the two functionalized triethoxysilanes in the feed. The physical properties of the UV-cured products were investigated in terms of Martens hardness, pencil hardness, and abrasion resistance.