2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide

It consists of thioxanthone or 2-isopropylthioxanthone in combination with (2,4,6-trimethylbenzoyl)-diphenyl-phosphine oxide or bis(2,4,6-trimethyl-benzoyl)-phenylphosphine oxide. The mechanism of sensitization was reported to involve triplet-triplet energy transfer from the thioxanthones to die phosphine oxides. That is followed by formation of radicals through a-cleavage of the photoinitiators. Direct photolysis of the phosphine oxides results in an absorptive, chemically induced, d)mamic electron polarization due to the triplet mechanism of polarization of the substituted benzoyl. The phosphoras-centered radicals produced by a-cleavage of the photoinitiators are the same radicals that... 

Trimethylbenzoyl-diphenyl-phosphine oxide has an excellent compatibility with other conventionally used components. Molecule cleaving type initiators, such as bis(2,4,6-trimethylbenzo-yl)-phenylphosphine oxide has a broad light absorbing spectrum. 

Phosphorus containing photoinitiators are useful in pigmented as well as in water based systems. Compounds like trimethylbenzoyl diphenyl phosphine oxide and its derivatives generally undergo a-cleavage. 

SCH 12] Schneider L.F.J., Cavalcante L.M., Prahl S.A. et al, Curing efficiency of dental resin composites formulated with camphorquinone or trimethylbenzoyl-diphenyl-phosphine oxide . Dental Materials, vol. 28, no. 4, pp. 392-397, 2012. 

Photoinitiators 2-hydroxy-2-methyl propiophenone and diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide both gave at least 100 MEKDR with no damage to the film surface when cured at a dosage as low as 0.5 J/cm2. This preference in photoinitiators has been observed in other studies of the maleate/vinyl ether system.1011... 

Photoinitated radical crosslinking of UPEAs was investigated further. For this study, the photoinitiator diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (Darocur TPO, research sample CIBA Speciality Chemicals) and the crosslinker, pentaerythritol tetraacrylate were employed. UPEA polymer films of [8]o.75 -Fum 0,25 - Leu(6) composition (Scheme 3), with Mw = 56 000 Da, PDI = 1.73, Tg = 19.7°C were cast onto a hydrophobic surface with 4 % w/w photoinitiator and 1 to 5 % w/w crosslinker (Scheme 5). Films of ca. 0.13 mm thickness were exposed to a broadband UV mercury lamp with the exposure rate 10 000 mW/cm. Sample was mounted 4 cm away from the source, irradiation time was 5 min. Tensile properties after exposure were measured. 

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