Oxygen-Mediated Reactions in Photopolymerizable Radical Thin Films: Application to Simultaneous Photocuring Under Air and Nanoparticle Formation.

Titanium propoxide, titanium isopropoxide, and titanium (triethanolaminato) isopropoxide are proposed as high-performance additives to overcome the oxygen inhibition effects in the free radical photopolymerization of a low-viscosity monomer thin film, under air and upon a low-intensity UV light activation. Indeed, when added to a Type I photoinitiator such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (BAPO), noticeably higher conversions are achieved under air (48% vs. 30%). The in situ formation of Ti-based nanoparticles is also observed. The photochemical properties of these types of Ti-based compounds as well as their interaction with BAPO are investigated by steady-state photolysis and electron spin resonance. Molecular orbital calculations give an interesting insight into the possible reactions. A chemical mechanism is also proposed. [ABSTRACT FROM AUTHOR]