A pyrrolo[3,2-b]pyrrole derivative used for one- and two-component radical photoinitiators for photopolymerization under 405 nm

Abstract

The new design is generally based on the improvement of existing commercial photoinitiators as well as the introduction of new building blocks aimed at improving the properties of polymerized materials. A photoinitiator named 1,4-bis(4-bromophenyl)-2,5-bis(4-(trifluoromethyl)phenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole (PyBF) with a symmetric trifluoromethyl (-CF3) end groups was synthesized through a one-step aldehyde–ketone condensation reaction. The -CF3 groups are introduced on the 2,5-position phenyl rings of the pyrrolo[3,2-b]pyrrole core, and PyBF shows visible light photoinitiation ability that matching with light-emitting diode (LED) of 405 nm. Both acrylate prepolymer and monomer have been applied to our photopolymerization formulas using PyBF as one-component photoinitiator. The thermal stability of PyBF is compared with commercial photointiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) with a comparable thermal decomposition temperature (Td) temperature above 300 oC. The SEM results show that the cured materials of PyBF/TPO/PEGDA mixture using PyBF/TPO as two-component photoinitiator system have smooth surface, instead of PyBF/PEGDA and TPO/PEGDA systems. Therefore, both the potential pyrrole-based one- and two-component photoinitiator for rational design is worth expected for visible light photopolymerization.