Methyl Benzoylformate Derivative Norrish Type I Photoinitiators for Deep-Layer Photocuring under Near-UV or Visible LED

Abstract

We designed and prepared a series of methyl benzoylformate (MBF) derivatives Norrish type I photoinitiators (MBFs) for light-emitting diode (LED)-induced photopolymerization through computer simulation. The potential photolysis mechanism of MBFs under LED at 405 nm was explored by steady-state photolysis, nuclear magnetic resonance, and electron spin resonance. The as-synthesized photoinitiator dimethyl 1,4dibenzoylformate (DM-BD-F) can efficiently initiate free radical photopolymerization of acrylate monomers under LED irradiation at 405 nm. Moreover, we predicted well the photoinitiating capability of MBFs through the cleavage exothermy (ΔH) calculated by triplet bond dissociation energy (BDE) and triplet energy (E T ). Significantly, based on the weak absorption of MBFs at 405 nm, MBFs were successfully applied to deep-layer photocuring and the curing depth reached 6.5 cm after the irradiation of LED at 405 nm for 30 s. This research provides a new idea and efficient strategy for the molecular design of photoinitiators for deep-layer photocuring.

Miniemulsion SI-ATRP by Interfacial and Ion-Pair Catalysis for the Synthesis of Nanoparticle Brushes

“…These hydroxyl radicals then initiate new polymer chains along with SiO 2 –Br initiating particle brushes. Since pyruvic acid (and pyruvate derivatives) mainly function in the aqueous phase, we use methyl benzoylformate (MBF), which not only has a similar molecular scaffold but is also miscible with monomer and hexadecane in the oil phase . In a subsequent control experiment, MBF was added into the oil phase (with BA and HD, but still excluding SiO 2 –Br initiator).…”

“…Since pyruvic acid (and pyruvate derivatives) mainly function in the aqueous phase, 74 we use methyl benzoylformate (MBF), which not only has a similar molecular scaffold but is also miscible with monomer and hexadecane in the oil phase. 75 In a subsequent control experiment, MBF was added into the oil phase (with BA and HD, but still excluding SiO 2 −Br initiator). Despite using ultrasound to generate the miniemulsion and running the reaction for 22 h, no monomer conversion was observed.…”

Recent advances on benzylidene cyclopentanones as visible light photoinitiators of polymerization

“…Notably, at present, no type I photoinitiators have been designed with benzylidene cyclopentanones such as oxime esters [102,107,230,232,235,236,[397][398][399][400][401] or glyoxylates for one photon polymerization. [402][403][404][405] Besides, it could greatly help to simplify the composition of the photocurable resins. Indeed, benzylidene cyclopentanones are efficient Type II photoinitiators but require the use of an additive.…”

Free-Radical Photopolymerization for Curing Products for Refinish Coatings Market

“…The electronic transitions that may occur in these systems are depicted in Figure 6 . However, among the outlined transitions, only n → π* and π → π*, the two lowest in energy, are available in the UV–vis spectrum [ 117 , 118 ].…”