New Phosphine Oxides as High Performance Near- UV Type I Photoinitiators of Radical Polymerization

Céline Dietlin,Thanh Tam Trinh,Jacques Lalevée,Stéphane Schweizer,Fabrice Morlet-Savary,Pierre-Antoine Noirot,Bernadette Graff

doi:10.3390/molecules25071671

Abstract

Carbazole structures are of high interest in photopolymerization due to their enhanced light absorption properties in the near-UV or even visible ranges. Therefore, type I photoinitiators combining the carbazole chromophore to the well-established phosphine-oxides were proposed and studied in this article. The aim of this article was to propose type I photoinitiators that can be more reactive than benchmark phosphine oxides, which are among the more reactive type I photoinitiators for a UV or near-UV light emitting diodes (LED) irradiation. Two molecules were synthesized and their UV-visible light absorption properties as well as the quantum yields of photolysis and photopolymerization performances were measured. Remarkably, the associated absorption was enhanced in the 350–410 nm range compared to benchmark phosphine oxides, and one compound was found to be more reactive in photopolymerization than the commercial photoinitiator TPO-L for an irradiation at 395 nm.

Highlights

Photopolymerization is an important process of synthesis of polymers as it is mostly a green technology
Details can be found found in the experimental part of the article, but the synthesis was straightforward
The spin densities for TPO-L and BAPO were 0.641 for the acyl radical and 0.509 and 0.426 for the phosphinoyl radicals, respectively. These results show that the acyl radical produced for CPO-1 and CPO-2 should have the same reactivity as the ones produced by TPO-L and BAPO

Summary

Introduction

Photopolymerization is an important process of synthesis of polymers as it is mostly a green technology (low energy consumption, no use of solvent, reaction at low temperature). It has applications in many industrial fields such as coatings, inks, adhesive optoelectronics, nanotechnologies, and 3D-printing [1,2,3,4,5,6,7,8,9,10]. To promote the use of LEDs in the near-UV range, new photoinitiators must be developed

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