A Water Soluble, Low Migration, and Visible Light Photoinitiator by Thioxanthone‐Functionalization of Poly(ethylene glycol)‐Containing Poly(β‐amino ester)

Abstract A novel photoinitiator (PI) is described here for low ecological impact, p(PEGDA575‐TX): It is water soluble, polymerizable, thioxanthone (TX) functional, and is a one‐component poly(ethylene glycol)‐based poly( β ‐amino ester). The PI is synthesized in one step via classical aza‐Michael addition reaction between poly(ethylene glycol) diacrylate ( M n = 575 D) and amine functionalized TX (2‐(2‐aminoethoxy)‐9H‐thioxanthen‐9‐one). It absorbs at ≈ 404 nm ( ε = 14 000–44 309) in water and can photodecompose with or without additives such as ethyl 4‐(dimethylamino)benzoate (EDB) and bis‐(4‐ tert ‐butylphenyl)‐iodonium hexafluorophosphate (Iod). Although it is an effective one‐component visible light PI for free radical polymerization of di‐ and tri(meth)acrylates, EDB or Iod will be favorable for synergistic effect. p(PEGDA575‐TX) has higher initiating reactivity, reducing ability of oxygen inhibition and migration stability compared to TX, which make it environmental friendly.