Novel chalcone derivatives with large conjugation structures as photosensitizers for versatile photopolymerization

Abstract

Four chalcones with large conjugation structures were designed and synthesized. Strong light absorption within the UV-vis range (λ max = 380-410 nm, ε max = 10,200-33,600 M −1 cm −1) matched the emission of light-emitting diodes within 385-450 nm. Compared with that of phenyl ring-containing chalcone, the bathochromic shift of the four chalcones was due to the enlarged conjugation structure and the intramolecular charge transfer effect. The reactive species produced from two-or three-component photoinitiating systems (PISs) based on chalcone-containing triphenyl amine and N-ethyl carbazole combined with an iodonium salt or/and an amine were highly efficient for versatile photopolymerizations (i.e., radical, cationic, blending, and thiol-ene polymerizations) upon soft exposure conditions (385-425 nm LEDs). UV-vis spectra, theoretical calculation, electrochemistry, real-time nuclear magnetic resonance spectra, and fluorescence quenching were investigated to determine the photochemical mechanism. Chalcone photoisomerization, which mainly occurred in anthracene-containing chalcone, weakened the initiation ability of the PISs. These chalcones have promising applications in photopolymerization.

Naphthalene-Based Oxime Esters as Type I Photoinitiators for Free Radical Photopolymerization

“…In addition, the rate of polymerization (R p ) is directly related to the heat flow (dH/dt) by Equation (2) [ 43 ]: R p = dC/dt …”

Recent advances on anthracene-based photoinitiators of polymerization

“…In 2021, CPD-14 was revisited by another group, except that the methoxy group of CPD-14 was replaced by an ethoxy group in CPD-19, unaffecting the optical properties (See Figure 10). [253] In this interesting work, influence of the cis/trans isomerization of chalcones on the photoinitiating ability was studied. A comparison between an anthracene and a triphenylamine-based chalcone (CPD-19 and CPD-20) was also established.…”

A new acrylated monomer from macaw vegetable oil that polymerizes without external photoinitiators

“…1, using the total area from the carbon double bonds at 1618 cm -1 and 1637 cm -1 ; where A t=0 is the total area for the monomeric mixture and A t=xs is the area value obtained for each polymer spectrum obtained at different times. Each polymerization was run over 300 s with a spectrum collected at 10 s intervals [8]. The rate of polymerization was calculated following the literature procedure [9].…”