Curing Behavior Study of UV-Curable Coatings Containing Nanosilica and Different Multifunctional Monomers via Depth Profiling Assessment

This study was done to assess the curing behavior of UV-curable coatings containing the multifunctional acrylate monomers, 1,6-hexanediol diacrylate (HDDA), trimethylolpropane triacrylate (TMPTA), and dipentaerythritol pentaacrylate (DiPEPA). Functionalized nanosilica was used for nano-based coating preparations. A microtome was used to cut each coating into three sections in order to study depth profiles of the coatings. FTIR and HPLC analyses were applied to determine degrees of double-bond conversion and quantities of residual monomer. The results showed that the biggest monomer in terms of size, DiPEPA, mainly remained at the surface of the microtomed sections. However, the bottom of microtomed sections had residual HDDA and TMPTA monomers. Similar behavior was observed in the nano-based coatings, and the degree of conversion at the bottom of the microtomed sections had noticeably increased.