Novel phenylamine‐based oxime ester photoinitiators for <scp>LED</scp>‐induced free radical, cationic, and hybrid polymerization

Abstract

Abstract Four new photoinitiators (PI's) containing various phenylamine‐based groups as chromophores and oxime ester (OXE) as initiating groups are proposed for the free radical polymerization, the cationic polymerization, and interpenetrated polymer networks upon visible light exposure using a light emitting diodes at 405 nm. These compounds showed outstanding polymerization photoinitiation ability, that is, high‐polymerization rates and good final reactive function conversions were obtained. The chemical mechanisms by which these OXE's generate reactive species were investigated through different techniques including real‐time Fourier transform infrared spectroscopy, UV–visible spectroscopy, fluorescence (time‐resolved or steady state) as well as cyclic voltammetry. Markedly, the proposed structures can be used as thermal initiators indicating all of them can be polymerized under suitable reaction temperature. In addition, due to their high efficiency, these optimized PI's were found to be useful @405 nm for both direct laser write and 3D printing applications.