Bis-acylphosphine oxide

Materials. The radical-type photopolymerizable formulation consisted of a mixture of hexanediol diacrylate (HDDA from UCB) and a polyurethane-diacrylate (Actilane 20 from Arkros). A bis-acylphosphine oxide (BAPO from Ciba) was used as photoinitiator at a typical concentration of 1 wt %. The cationic type photopolymerizable resin consisted of a mixture of the divinylether of triethyleneglycol (RapiCure DVE-3 from ISP) and a divinylether derivative of bis-phenol A (DVE-BPA). The cationic photoinitiator (Cyracure UVI-6990 from Union Carbide) had a composition of 50 wt % of mixed triarylsulfonium hexafluorophosphate salts and 50 wt % of propylene carbonate. The BAPO initiator... 

Other initiator systems have been used, such as PPD (l-phenyl-l,2-propanedione) [14] and bis-acylphosphine oxide [15]. They have the advantage of being less intensely coloured than camphorquinone, and consequently there is a much closer colour match between the composite in its cured and uncured states. This makes choosing the correct shade of composite to match the tooth more straightforward [8]. Despite the differences in the chemistry of these substances, their essential mode of action is the same in all cases. They become excited by light of a specific wavelength, as a result of which they fragment into free radicals, and the free radicals then go on to promote polymerization of the monomers. 

Alkyl ethers of benzoin Benzil dimethyl ketal 2-Hydroxy-2-methylphenol-l-propanone 2,2-Diethoxyacetophenone 2-Benzyl-2-At, V-dimethylamino- l-(4-morpholinophenyl) butanone Halogenated acetophenone derivatives Sulfonyl chlorides of aromatic compounds Acylphosphine oxides and bis-acyl phosphine oxides Benzimidazoles... 

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