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Keto‐coumarin scaffold for photoinitiators for 3D printing and photocomposites
Author(s) -
Abdallah Mira,
Dumur Frédéric,
Hijazi Akram,
Rodeghiero Giacomo,
Gualandi Andrea,
Cozzi Pier G.,
Lalevée Jacques
Publication year - 2020
Publication title -
journal of polymer science
Language(s) - English
Resource type - Journals
eISSN - 2642-4169
pISSN - 2642-4150
DOI - 10.1002/pol.20190290
Subject(s) - photopolymer , cationic polymerization , polymerization , photochemistry , chemistry , fourier transform infrared spectroscopy , irradiation , coumarin , radical polymerization , polymer chemistry , materials science , polymer , organic chemistry , chemical engineering , physics , nuclear physics , engineering
The purposes of this paper are moving toward (a) the development of a new series of photoinitiators (PIs) which are based on the keto‐coumarin (KC) core, (b) the introduction of light‐emitting diodes (LEDs) as inexpensive and safe sources of irradiation, (c) the study of the photochemical mechanisms through which the new PIs react using different techniques such as Fourier transform infrared, UV–visible or fluorescence spectroscopy, and so on, (d) the use of such compounds (presenting good reactivity and excellent photopolymerization initiating abilities) for two specific and high added value applications: 3D printing (@405 nm) and preparation of thick glass fiber photocomposites with excellent depth of cure, and finally (e) the comparison of the performance of these KC derivatives versus other synthesized coumarin derivatives. In this study, six well‐designed KC derivatives ( KC‐C , KC‐D , KC‐E , KC‐F , KC‐G , and KC‐H ) are examined as high‐performance visible‐light PIs for the cationic polymerization of epoxides as well as the free‐radical polymerization of acrylates upon irradiation with LED@405 nm. Excellent polymerization rates are obtained using two different approaches: a photo‐oxidation process in combination with an iodonium (Iod) salt and a photo‐reduction process when associated with an amine ( N ‐phenylglycine or ethyl 4‐(dimethylamino)benzoate). High final reactive conversions were obtained. A full picture of the involved photochemical mechanisms is provided.