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Photophysical and Photochemical Studies of Novel Thioxanthone‐Functionalized Methacrylates through LED Excitation
Author(s) -
Eren Tugce Nur,
Yasar Nurdan,
Aviyente Viktorya,
MorletSavary Fabrice,
Graff Bernadette,
Fouassier Jean Pierre,
Lalevee Jacques,
Avci Duygu
Publication year - 2016
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201600051
Subject(s) - thioxanthone , chemistry , photochemistry , photoinitiator , photopolymer , trifluoroacetic acid , polymerization , isopropyl , flash photolysis , ketyl , radical polymerization , polymer chemistry , benzophenone , monomer , organic chemistry , polymer , kinetics , reaction rate constant , physics , quantum mechanics
Five novel thioxanthone (TX)‐functionalized methacrylates as copolymerizable photoinitiators (CopPIs) for polymerization of acrylates are synthesized from reactions of tert ‐butyl α‐bromomethacrylate with 2‐hydroxy thioxanthone (TX1) and 1,4‐dihydroxy thioxanthone (TX3), cleavage of their respective tert ‐butyl ester groups with trifluoroacetic acid (TX2, TX4), and by reaction of the acid chloride derivative of TX2 with Irgacure 2959 (TX5). These CopPIs absorb in the near UV–visible region (390–420 nm; absorption redshift ≈10–40 nm, ε values comparable to TX). Their performances are studied under LED exposure at 385 and 405 nm using real‐time FTIR. The reactivities of TX1 and TX2 are similar to isopropyl thioxanthone, used as reference; TX3 and TX4 have lower reactivities, due to their difunctionality, which however makes them good crosslinking agents. TX5 is the first monomeric PI possessing two different type side‐chain photoinitiating groups. The migration stability of two of these CopPIs is shown in the cured polyacrylates. The photochemical mechanisms are studied by electron spin resonance, steady state photolysis, laser flash photolysis, and cyclic voltammetry.