Soybean oil containing thioxanthone (TX) moieties and/or coinitiator DBA (ESO-ATX-DBA, ESO-ATX/ESO-DBA) were synthesized by grafting 2-acitic thioxanthone (ATX) and 4-(dimetheylamino) benzoic acid (DBA) to the backbone of epoxidized soybean oil (ESO). The obtained ESO-ATX-DBA, ESO-ATX and ESO-DBA were characterized by FT-IR, H-1 NMR and UV-vis spectra, and investigated as photoinitiators by photo-DSC. Photoinitiator systems ESO-ATX-DBA and ESO-ATX/ESO-DBA were more efficient than their low-molecular weight analogues (chemical mixture of ETX-DBA and physical mixture of ETX/EDB) especially in the photopolymeriztion of acrylate monomers containing pigment. Moreover. ESO-ATX-DBA exhibited much lower migration in comparison with their low-molecular weight analogues. These characteristics gave the obtained TX containing soybean oil potential in the application of ink, and these studies also provide alternative approach to prepare polymeric photoinitiators from the renewable source. (C) 2012 Elsevier Ltd. All rights reserved.