A pyrrole–carbazole photoinitiator for radical and cationic visible light LED photopolymerization

Yang Li, Usman Shaukat, Sandra Schlögl, Tanlong Xue, Jingfang Li, Jun Nie, Xiaoqun Zhu

Research output: Contribution to journalArticleResearchpeer-review


Driven by the growing demand towards low cost and environmentally friendly curing processes, the synthesis of visible light absorbing photoinitiators has been a significant research direction in the field of photopolymerization in the past couple of years. Herein, a novel synthesis route is introduced to obtain a bifunctional pyrrole-carbazole-based photoinitiator (ECMO) via one-step reaction. On account of its excellent absorption at 405 nm and the ability for hydrogen donation, ECMO can initiate free radical polymerization upon visible light exposure and forms colorless photopolymers. Notably, ECMO is further able to act as sensitizer for triarysulfonium salts and significantly extends the absorption window of the onium salts into the visible light spectral region. ECMO sensitized triarysulfonium salts show superior curing performance in cationic polymerization (e.g. higher final monomer conversion) compared to conventional isopropylthioxanthone/triarysulfonium hexafluorophosphate systems. In addition, thermogravimetric analysis shows that ECMO possesses exceptional thermal stability, which facilitates its practical application in photopolymerization processes.
Original languageEnglish
Article number111700
Number of pages7
JournalEuropean polymer journal
Issue number3 January
Early online date10 Nov 2022
Publication statusPublished - 3 Jan 2023

Bibliographical note

Publisher Copyright: © 2022 Elsevier Ltd


  • LED, cationic polymerization
  • Photoinitiator
  • Triarylsulfonium salts
  • Visible light

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