Study on bifunctional acyldiphenylphosphine oxides photoinitiator for free radical polymerization

Product Variation in Reactions of MI3(thf)4 with Bis(Mesitoyl)Phosphide Across the M = U, Np, Pu Series

A series of reactions using sodium bis(mesitoyl)phosphide (MesBAP-) with the actinide starting material AnI3(thf)4 (An = U, Np, Pu) as well as the analogous reaction with CeI3(thf)4 was performed. Similar U and Np An(MesBAP)4 (An = U, Np) products were obtained in the +4-oxidation state. The thorium homologue was synthesized using ThI4(dme)2 to generate Th(MesBAP)4, which was employed as a diamagnetic and predominantly redox inert metal center for comparison. The resulting product isolated from the analogous reaction with PuI3(thf)4 was [Na(thf)][Pu(MesBAP)4], where the metal coordinated four ligands and retained the +3-oxidation state. This result is distinct from that obtained from the reaction with CeI3(thf)4, where the Ce3+ product was Ce(MesBAP)3(thf)2. The compounds were isolated and characterized by X-ray diffraction, ultraviolet-visible (UV-vis)-nIR and NMR spectroscopies, and cyclic voltammetry. The synthetic results reveal how different redox stabilities across the 5f series can result in divergent reactivity of Pu. Electrochemical experiments produced redox features that suggest the potential to form reduced complexes supported by the MesBAP ligand framework.

High-Performance Sunlight-Induced Polymerized Hydrogels and Applications in 3D and 4D Printing

Currently, there are only few reports on water-soluble photoinitiating systems. In this study, a highly water-soluble organic dye i.e. sodium (E)-3,3'-((4-(2-(3-methylbenzo[d]thiazol-3-ium-2-yl)vinyl)phenyl)azanediyl)dipropionate iodide, was synthesized and served as a photoinitiator. Notably, this water-soluble initiator, at a low concentration of just 0.01 wt%, demonstrates a high photoinitiation ability, with some hydrogel formulations achieving nearly 100% double bond conversion under sunlight. Photopolymerization kinetics were monitored using Real-Time Fourier Transform Infrared. To explore the complex chemical principles of radical polymerization, UV-visible absorption and fluorescence spectroscopy, steady-state photolysis, fluorescence quenching experiments and cyclic voltammetry were employed to gain a comprehensive understanding of the photochemical mechanism involved. Additionally, several characteristics of the synthesized hydrogels were also investigated i.e. the water content, the water swelling, and the volume swelling. In addition to their excellent photoinitiation capabilities, the hydrogel formulations developed in this study also supported 3D printing. 3D objects with smooth surface and a high spatial resolution could be successfully printed using direct laser writing. The fabricated hydrogels could reversibly change of shape in response to water (adding or removing water), enabling successful 4D printing behavior. Furthermore, the efficient photoinitiation ability of the water-soluble formulations opens new avenues for sunlight-polymerized hydrogels and potential applications in bioprinting.

Fats and Oils as a Sustainable Source of Photopolymerizable Monomers

Bio-derived monomers and biobased building blocks obtained from natural sources, e.g., fats and oils, are attracting increasing attention mainly due to sustainability concerns. Due to their features, renewable feedstocks are an excellent alternative to petroleum-based raw materials to shift towards greener chemistry, especially when coupled with energy-efficient processes like photopolymerization. In this review, we illustrate the recent research outcomes in the field of photocurable biobased monomers, showing the advantages of using biobased chemicals for the synthesis of photocurable monomers and the potential of naturally derived building blocks in photocuring reactions.

Phenothiazine Derivative-Based Photoinitiators for Ultrafast Sunlight-Induced Free Radical Polymerization and Rapid Precision 3D Printing

In this work, we introduce twenty-six phenothiazine derivatives (PTZs) that were designed and synthesized as visible light photoinitiators. These compounds, in combination with an amine [ethyl 4-(dimethylamino)benzoate (EDB)] and an iodonium salt [di-tert-butylphenyl iodonium hexafluorophosphate (Iod)], could furnish high-performance three-component (PTZs/EDB/Iod) photoinitiating systems that were employed for the free radical polymerization of thick films of a low-viscosity model acrylate resin, namely, trimethylolpropane triacrylate (TMPTA) under visible light and sunlight exposure. A commercial thioxanthone, i.e., isopropylthioxanthone (ITX) was selected to design a reference ITX/EDB/Iod photoinitiating system. Double bond conversions of 87% and 76% were measured for the developed and synthesized photoinitiating systems under 405 and 450 nm light-emitting diode irradiation, respectively, and a conversion as high as 70% could be determined under sunlight irradiation─about 23 times higher than the conversion obtained with the comparable system prepared with the commercial photoinitiator. The relevant photoinitiation abilities and photochemical mechanisms are comprehensively investigated by a combination of techniques including real-time Fourier transform infrared spectroscopy, UV-visible absorption spectroscopy, fluorescence spectroscopy, steady-state photolysis, cyclic voltammetry, and electron paramagnetic resonance. Notably, the exceptional performance of the photoinitiators enabled the fabrication of 3D objects with precise morphology and superior resolution through 3D printing and direct laser write techniques. These findings not only provide opportunities for efficient polymerization under artificial and natural light conditions but also pave the way for scalable, cost-effective, environmentally sustainable, and green chemistry-driven curing applications.

Novel High-Performance Glyoxylate Derivative-Based Photoinitiators for Free Radical Photopolymerization and 3D Printing with Visible LED

Investigations concerning the glyoxylate moiety as a photocleavable functional group for visible light photoinitiators, particularly in the initiation of free radical photopolymerization remain limited. This study introduces nine innovative carbazole-based ethyl glyoxylate derivatives (CEGs), which are synthesized and found to exhibit excellent photoinitiation abilities as monocomponent photoinitiating systems. Notably, these structures demonstrate robust absorption in the near-UV/visible range, surpassing the commercial photoinitiators. Moreover, the newly developed glyoxylate derivatives show higher acrylate function conversions compared to a benchmark photoinitiator (MBF) in free radical photopolymerization. Elucidation of the photoinitiation mechanism of CEGs is achieved through a comprehensive analysis involving the decarboxylation reaction and electron spin resonance spin trapping. Furthermore, their practical utility is confirmed during direct laser writing and 3D printing processes, enabling the successful fabrication of 3D printed objects. This study introduces pioneering concepts and effective strategies in the molecular design of novel photoinitiators, showcasing their potential for highly advantageous applications in 3D printing.

Light-Mediated Polymerization Catalyzed by Carbon Nanomaterials

Carbon nanomaterials, specifically carbon dots and carbon nitrides, play a crucial role as heterogeneous photoinitiators in both radical and cationic polymerization processes. These recently introduced materials offer promising solutions to the limitations of current homogeneous systems, presenting a novel approach to photopolymerization. This review highlights the preparation and photocatalytic performance of these nanomaterials, emphasizing their application in various polymerization techniques, including photoinduced i) free radical, ii) RAFT, iii) ATRP, and iv) cationic photopolymerization. Additionally, it discusses their potential in addressing contemporary challenges and explores prospects in this field. Moreover, carbon nitrides, in particular, exhibit exceptional oxygen tolerance, underscoring their significance in radical polymerization processes and allowing their applications such as 3D printing, surface modification of coatings, and hydrogel engineering.

Cyclopolymerizable and cyclopolymeric photoinitiators from diallyl amine and α-hydroxy ketones

Two novel cyclopolymerizable and one cyclopolymeric (first in the literature) PIs with high reactivity, controllable water solubility, migration stability and high thermal stability were synthesized by attachment of diallyl amine to I2959 or I184.