Novel self‐initiating UV‐curable acrylate monomers

Abstract

AbstractBased on the addition reaction of hydroxyl groups and the isocyanate groups in the bi‐functional monomer acroyloxyethyl isocyanate (AOI), two novel self‐initiating ultraviolet (UV)‐curable acrylate monomers were synthesized from benzoin and 2‐hydroxy‐4′‐(2‐hydroxyethoxy)‐2‐methylpropiophenone (commercial‐available Irgacure® 2959), and the products were denoted as Benzoin‐AOI and 2959‐AOI, respectively. The chemical structures of the products were confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The UV–visible absorption spectrum showed that the self‐initiating acrylates exhibited similar maximum absorption wavelengths to both benzoin (250 nm) and Irgacure® 2959 (270 nm). When the products were continually exposed to a mercury lamp, the maximum absorption peak gradually blue shifted, showing that the products decomposed under the UV radiation. The photo differential scanning calorimetry (Photo‐DSC) analysis showed that the self‐initiating monomers could initiate the polymerization of 1,6‐hexanediol diacrylate (HDDA) as quickly as the original photo‐initiator, and the efficiency of Benzoin‐AOI was slightly lower than that of benzoin, while for 2959‐AOI, the efficiency remained stable after being linked to the AOI moiety. The cytotoxicity assay against fibroblasts cell line L929 showed that 2959‐AOI exhibited lower cytotoxicity at low dosages but higher cytotoxicity at high dosages compared to Irgacure® 2959 after the introduction of the AOI structure.