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Issue 8, 2020
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Triphenylamine-hexaarylbiimidazole derivatives as hydrogen-acceptor photoinitiators for free radical photopolymerization under UV and LED light

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Abstract

In this study, three triphenylamine-based hexaarylbiimidazole (HABI) derivatives featuring different numbers of methoxy groups (none for HABI1, two for HABI2, and four for HABI3) have been synthesized. For comparison, a common hydrogen acceptor photoinitiator, ocl-HABI (2-chlorohexaarylbiimidazole), was also applied to compare the corresponding properties. The new HABIs displayed a more red-shifted and higher molar extinction coefficient than ocl-HABI with the absorption region extended to visible light. A larger free radical concentration of HABIs was also achieved, which was confirmed via electron paramagnetic resonance (ESR) spectroscopy. These visible light-sensitive HABIs or ocl-HABI in combination with a suitable hydrogen donor, i.e., N-phenyl glycine (NPG) were utilized as photoinitation systems for conventional radical polymerization (RDRP). All the packages exhibited good electron-transfer ability by the calculation of the free energy changes (ΔGET). The HABI1/NPG system exhibited the best double bond conversion efficiency and outperformed the corresponding ocl-HABI/NPG-based formulation under similar UV light source testing conditions. We then employed the HABI1/NPG and ocl-HABI/NPG systems for LED light source testing. Again, HABI1/NPG had better photocuring conversion efficiency and shorter time at maximum heat flow than ocl-HABI/NPG, indicating that the HABI1/NPG system can be applied to light curing applications under different light sources, such as UV and LED.

Graphical abstract: Triphenylamine-hexaarylbiimidazole derivatives as hydrogen-acceptor photoinitiators for free radical photopolymerization under UV and LED light

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Supplementary files

Article information


Submitted
24 Oct 2019
Accepted
30 Dec 2019
First published
02 Jan 2020

Polym. Chem., 2020,11, 1504-1513
Article type
Paper

Triphenylamine-hexaarylbiimidazole derivatives as hydrogen-acceptor photoinitiators for free radical photopolymerization under UV and LED light

Y. Li and Y. Chen, Polym. Chem., 2020, 11, 1504
DOI: 10.1039/C9PY01605H

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