title: The first photochemical in situ production of Ti-based nanoparticles: a SH2 strategy using bis(cyclopentadienyl)titanium dichloride (Cp2TiCl2).
abstract: Bis(cyclopentadienyl)titanium dichloride (Cp2TiCl2) is a high performance additive under UV light activation for both i) radical photopolymerization reactions (when added to a Type I photo-initiator such as 2,2-dimethoxy-2-phenylacetophenone, the oxygen inhibition is reduced) and ii) a concomitant in situ photoinduced and oxygen mediated formation of Ti-based nanoparticles (diameters ranging from 45 to 220 nm). The photochemical properties of Cp2TiCl2 are investigated by steady state photolysis and electron spin resonance, and its photoinitiation ability checked. The nanoparticles (NPs) are well characterized by transmission electron microscopy. The high reactivity of Cp2TiCl2 under air is ascribed to a bimolecular homolytic substitution (the SH2 process is clearly demonstrated by density functional theory calculations and ESR experiments), which converts the peroxyls into new efficient initiating radicals. The photochemical in situ incorporation of Ti NPs has never previously been reported. The synthesis of metal nanoparticles by a SH2 approach instead of the reduction of a metal salt appears to be a promising original method.
authors.affiliation: Institut de Chimie et des Matériaux Paris-Est - UMR 7182, Université Paris-Est Créteil (UPEC), Equipe "Systèmes Polymères Complexes", 2-8 rue Henri Dunant, 94320, Thiais, France.
authors.forename: Davy-Louis
authors.initials: DL
authors.lastname: Versace
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Fouassier
authors.forename: Jacques
authors.initials: J
authors.lastname: Lalevée
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000814:Aniline Compounds / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D055668:Photochemical Processes; D010782:Photolysis / Q000528:radiation effects; D058105:Polymerization / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D000179:Acrylates; D000814:Aniline Compounds; D009942:Organometallic Compounds; C027993:trimethylolpropane triacrylate; C050795:N,N-dimethyl-4-anisidine; D014025:Titanium
keywords: bimolecular homolytic substitution reaction (SH2); free radical photopolymerization; oxygen inhibition; titanium nanoparticles