Recent advances on visible light Phenothiazine-based photoinitiators of polymerization

Visible light photoinitiators of polymerization are actively researched as these molecules can advantageously address the light penetration issue within the photocurable resins. With aim at developing dyes using a scaffold that can be easily modified, phenothiazine is one of those. In this review, an overview of the recent developments concerning phenothiazine-based photoinitiators of polymerization is provided. Over the years, structures of photoinitiators have greatly evolved and phenothiazine is now exclusively included in photoinitiators of more complex structures and not used alone as during the pioneering works. Using this unprecedented approach, Type I and Type II photoinitiators have been designed and synthesized. To evidence the pertinence of the approach, comparisons with reference photoinitiating systems will be provided.