Yellow Triazine as an Efficient Photoinitiator for Polymerization and 3D Printing under LEDs

Abstract

The search for new efficient photoinitiators for polymerization under the illumination of visible light is under extensive investigation due to their wide application in 3D printing. 2‐(4‐Methoxystyryl)‐4,6‐bis(trichloromethyl)‐1,3,5‐triazine (yellow triazine, R‐Cl) alone or the R‐Cl/additive systems have been indicated as promising photoinitiating systems in the free radical polymerization at 405 nm in our previous study. Here, further investigation of R‐Cl in the polymerization of a series of difunctional (meth)acrylate monomers is described. The effect of monomers on the polymerization performance is elucidated. The interplay of functional group, double bond concentration, and fluidity determines the polymerization rate and final conversions. Remarkably, R‐Cl shows better photoinitiating ability than well‐known commercial photoinitiator bisacylphosphine oxide in the polymerization of bis‐GMA/TEGDMA blend and EB605 under LED at 400 nm. The optimum concentrations of R‐Cl in the photopolymerization of TetEGDA and DPGDA monomers are revealed, the results of which are used to guide the 3D printing of DPGDA.

Rational Design of Acyldiphenylphosphine Oxides as Photoinitiators of Radical Polymerization

“…The recent elegant works of the Liska, − Haas, Gescheid , and Barner-Kowollik groups on acylsilanes, acylstannanes, and acylgermanes show the interest of finding new PIs absorbing above 400 nm. 1-Aryl-2-(triisopropyl­silyl)­ethane-1,2-diones, silyl glyoxylates, oxime esters, − N -phenylglycine, dibenzothiophene-based oxalates, and triazine have been proposed to work with LEDs between 400 and 550 nm, showing the interest to develop new type I radical photoinitiators working under visible light. The computed guided development of novel structures has been recently exemplified in ref .…”

Recent advances on push–pull organic dyes as visible light photoinitiators of polymerization

“…Espe cially, by combining elongation of the π-conjugated spacer and extension of the polyaromaticity of the electron acceptor, a dye absorbing in the near infrared region could be even prepared (PP29). Despites their huge differences concerning the absorptions of the 21 dyes, choice was done by the authors to test the different dyes only at 405 nm which is currently the wavelength under use in 3D printers [177][178][179]. Only their ability to induce the FRP of the tetrafunctional acrylate-based Ebecryl 40 was examined.…”

Recent advances on naphthalic anhydrides and 1,8-naphthalimide-based photoinitiators of polymerization

“…[97] By introducing a piperidinyl group at the 6-position of the naphthalic anhydride core, an absorption extending from 350 to 550 nm could be obtained, making NAPHT-1 an excellent candidate for photopolymerization carried out at 405 nm, corresponding presently to the wavelength under use in 3D printers. [98][99][100] When used in combination with an iodonium salt (Iod), N-vinylcarbazole (NVK), an amine (MDEA) or a triazine (R-Cl), the resulting photoinitiating systems could efficiently promote various types of photopolymerizations, including the free radical polymerization (FRP) of (meth)acrylates (TMPTA), the cationic polymerization (CP) or the free radical promoted cationic polymerization (FRPCP) of epoxides (EPOX) and vinylether monomers (DVE-3), the dual cure of acrylate/epoxide (TMPTA/EPOX) blends or the thiol-ene (trithiol/DVE-3) photopolymerization (see Scheme 2).…”