Recent Advances in Visible Light Photoinitiating Systems Based on Flavonoids

The design of biosourced and/or bioinspired photoinitiators is an active research field as it offers a unique opportunity to develop photoinitiating systems exhibiting better biocompatibility as well as reduced toxicity. In this field, flavonoids can be found in numerous fruits and vegetables so these structures can be of interest for developing, in the future, polymerization processes, offering a reduced environmental impact but also better biocompatibility of the polymers. In this review, the different flavonoids reported to date as photoinitiators of polymerization are presented. Over the years, different modifications of the flavonoid scaffold have been examined including the grafting of well-known chromophores, the preparation of Type II photoinitiators or the introduction of photocleavable groups enabling the generation of Type I photoinitiators. Different families of flavonoids have also been investigated, enabling to design of high-performance photoinitiating systems.