N-ethyl carbazole-1-allylidene-based push-pull dyes as efficient light harvesting photoinitiators for sunlight induced polymerization. (15th March 2021)

• Record Type: Journal Article
• Authors: Sun, Ke; Liu, Shaohui; Chen, Hong; Morlet-Savary, Fabrice; Graff, Bernadette; Pigot, Corentin; Nechab, Malek; Xiao, Pu; Dumur, Frédéric; Lalevée, Jacques
• Is Part Of: European polymer journal. Volume 147(2021)
• Publication Date: 2021-03-15
• Subjects: Push-pull dye -- Free radical polymerization -- Three-component system -- LED -- Sunlight -- 3D printing; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2021.110331
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Highlights: 12 new push-pull dyes (never synthesized before) were synthesized and examined for their photoinitiation abilities. The new dyes are efficient for direct laser write experiments. A clear picture of the photochemical mechanisms is provided. A specific dye (dye 8) proved to be the most reactive photoinitiator of the series upon irradiation with sunlight. Abstract: In this article, the free radical polymerization of acrylates was successfully achieved with a series of twelve push-pull chromophores comprising the N -ethyl carbazole-1-allylidene group as the electron-donating group. Using this strong donor, the resulting dyes, never synthesized before, could efficiently initiate the free radical photopolymerization of acrylates upon mild irradiation conditions e.g. using sunlight. These novel multi-component systems comprising the above mentioned push-pull dyes, a tertiary amine (ethyl dimethylaminobenzoate EDB) and an iodonium salt could act as efficient photoinitiating systems (PISs) in free radical polymerization (FRP), leading to the formation of 3D patterns with precise shapes under the direct laser write (DLW) approach. Among these new PISs, dyes 3, 6, 7 and 8 were selected due to their efficient photoinitiation performances for chemical mechanism studies including steady state photolysis, fluorescence quenching measurements, electron spin resonance (ESR) spin-trapping experiments and cyclic voltammetry. Markedly, their excellent photochemical reactivities prompted us to investigate the performance of these multi-component photoinitiating systems upon sunlight as an ecofriendly approach. As a result, this research proved that sunlight could be used as a potential light source that can advantageously replace LEDs when highly reactive push-pull dyes are used as photosensitizers for the free radical photopolymerization of acrylate resins. Finally, 3D patterns could be prepared with the new photocomposites, and silica fillers could be even incorporated within the photosensitive resins so that a gradient of resolution could be successfully demonstrated.