Julolidine or Fluorenone Based Push−Pull Dyes for Polymerization upon Soft Polychromatic Visible Light or Green Light. Pu Xiao, † Michel Frigoli, ‡ Fre ́ de ́ ric Dumur, §,⊥,∥ Bernadette Graff, † Didier Gigmes,* ,§ Jean Pierre Fouassier, ○ and Jacques Laleve ́ e †, * † Institut de Science des Mate ́ riaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, rue Jean Starcky, 68057 Mulhouse Cedex, France ‡ Institut Lavoisier de Versailles, UMR CNRS 8180, UVSQ, 45 avenue des Etats-Unis, 78035 Versailles Cedex, France § Aix-Marseille Universite ́ , CNRS, Institut de Chimie Radicalaire, UMR 7273, F-13397 Marseille, Cedex 20, France ⊥ Univ. Bordeaux, IMS, UMR 5218, F-33400 Talence, France ∥ CNRS, IMS, UMR 5218, F-33400 Talence, France * S Supporting Information ABSTRACT: Two push−pull dyes (a julolidine derivative DCJTB and a fluorenone-co-amino phenyl derivative h-B3FL), incorporated in multicomponent photoinitiating systems have been investigated for the cationic polymerization of epoxides or the radical polymerization of acrylates under visible light irradiations (household halogen lamp or green laser diode at 532 nm). The DCJTB/iodonium salt (and optionally N- vinylcarbazole) based systems are pretty efficient for the cationic polymerization of epoxides. Both dyes, when combining with an amine and 2,4,6-tris(trichloromethyl)- 1,3,5-triazine, exhibit a good efficiency in the radical polymerization of acrylates. The photochemical mechanisms are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin trapping techniques. ■ INTRODUCTION Actually, the design of new photoinitiating systems (PISs) is the subject of many works (see, e.g., in refs 1−14), particularly on their use under visible lights. Indeed, visible lights are associated with cheaper and safer irradiation devices (e.g., xenon lamps, LED arrays, laser diodes, household halogen lamps and LEDs, fluorescent bulbs, sunlight, ...) and are characterized by a strongly growing interest in various research fields such as materials, optics, medicine, dentistry, micro- electronics, and nanotechnology etc. Push−pull molecules are interesting and promising compounds that can be incorporated in photoinitiating systems (PISs) for such irradiation conditions. They consist in substituted D-π-A structures with electron donor (D) and electron acceptor (A) functionalities at both ends of a planar conjugated spacer, which endows this class of molecules with a strong light absorption in the visible region. 15,16 Very recently, we have reported several push−pull molecules usable in PISs, e.g. (thio)barbituric acid derivatives for dye photosensitized free radical polymerization (FRP) and cationic polymerization (CP)/free radical promoted cationic polymerization (FRPCP) under blue lights, Michler’s ketone derived dyes for FRP, CP/FRPCP under blue to green lights, and indanedione derivatives for FRP, CP/FRPCP under blue to red lights. 16−18 The challenge is still open for the continuous disclosure of new push−pull dyes. In the frame of our research to develop novel PISs in this area, we have selected here a julolidine derivative DCJTB and a fluorenone-co-amino phenyl derivative h-B3FL already developed for applications in optics and semiconducting materials 19 (Scheme 1). DCJTB is one of the most efficient red-fluorescent dyes encountered in OLEDs; it exhibits an excellent light absorption in the blue and green region; 20 julolidine related compounds used in photopolymer technology have been patented a long time ago (see, e.g., in refs 21 and 22). h-B3FL is also an interesting compound with a D- π-A-π-D structure exhibiting a high thermal and photochemical stability; a derivative based on a dibutylamino substitution (and noted B3FL) has also found an elegant application in two- photon-induced photopolymerization. 23,24 In the present paper, these two dyes have been incorporated into PISs (containing an iodonium salt and optionally N- vinylcarbazole, amine and 2,4,6-tris(trichloromethyl)-1,3,5- triazine) for the CP/FRPCP of an epoxide or the FRP of an acrylate under visible light sources i.e. a very soft household halogen lamp (>370 nm) and laser diodes at 473 or 532 nm. Received: October 24, 2013 Revised: December 4, 2013 Published: December 27, 2013 Article pubs.acs.org/Macromolecules © 2013 American Chemical Society 106 dx.doi.org/10.1021/ma402196p | Macromolecules 2014, 47, 106−112