Herein, thirteen ketone derivatives composed of different cyclohexanone cores and peripheral moieties are designed, among which 10 ketones have never been synthesized before. These ketones are proposed as high‐performance photoinitiators for both free radical polymerizations and cationic polymerizations under soft conditions (visible LED@405 nm irradiation at room temperature). In combination with an amine and an iodonium salt (Iod), these ketones could be used in three−component photoinitiating systems to initiate the free radical polymerization of acrylates with distinct final conversions, among which the ketone−1/amine/Iod combination proved to be the most efficient one. Besides, the ketone−1/Iod two−component system also showed a remarkable photoinitiation ability for the cationic polymerization of epoxides. The photochemical sensitivity of ketone−1 in the presence of an amine and an iodonium salt was systematically investigated by steady state photolysis and excited state fluorescence quenching characterizations, respectively. Interestingly, macroscopic 3D patterns with excellent spatial resolution could be generated using the ketone−1/amine/Iod photoinitiating system for the free radical polymerization of acrylates. This high performance is also found useful to overcome the light penetration issue for the access to filled samples (silica) and the preparation of composites.

The introduction of metallic fillers to polymers via the photopolymerization approach can endow the composite materials with some unique properties, but the relevant research is still scarce due to the issue of light penetration and inner filter effect. Herein, for the first time the fabrication of photocomposites based on fine iron powder (i.e., a typical kind of metallic filler) is reported in this work. The free radical polymerization of two different acrylate monomers, poly(ethylene glycol) diacrylate and trimethylolpropane triacrylate, is performed in the presence of iron filler under mild conditions (i.e., light emitting diode (LED)@405 nm irradiation at room temperature under air). And the real‐time Fourier transform infrared spectroscopy reveals remarkable photopolymerization kinetics of acrylates with high final conversions and fast polymerization rates despite the increasing contents of iron filler in the composites. Interestingly, the 3D printing technique is applied to the iron filler‐based composites to produce tridimensional patterns with excellent spatial resolution. This work not only paves the way for the investigation of photocomposites based on metallic fillers through photochemical methods, but also broadens the potential application prospects.

No abstract

Polydiacetylene (PDA) is a promising material due to the chromatic transition through external stimulus. However, near‐infrared (NIR) light is on the periphery of attention to achieve the colorimetric change. Herein, an epoxy‐based PDA composite is prepared through a dual‐wavelength orthogonal photopolymerization strategy where 405 nm light and UV light are utilized in turn. The appearance of blue phase indicates that ene–yne‐conjugated PDA backbone is successfully formed in the composite. The generated PDA composite exhibits a blue‐to‐red color change upon heating. More interestingly, the fast chromatic transition is also observed under a laser diode at 1064 nm irradiation in the presence of a NIR dye (IR 1064). And such NIR light responsiveness of the composite upon NIR light irradiation is demonstrated by thermal imaging camera. Finally, the 3D printing technique is applied to the composite and the fabricated 3D pattern exhibits dual colorimetric transition in response to both heat and NIR light stimuli. Therefore, the newly proposed approach finds great applications in functional materials due to the unique dual thermal or NIR light stimuli responsiveness.

No abstract