The influence of admixtures on the course of hydrolysis of titanyl sulfate

The study focused on the question how admixtures, such as iron(II), iron(III), magnesium and aluminium salts influence the degree of TiOSO4 conversion to hydrated titanium dioxide (HTD). Titanyl sulfate solution, an intermediate product in the industrial preparation of titanium dioxide pigments by sulfate route was used. The admixtures were added to the solution and their concentration was gradually changed. It was found that hydrolysis clearly depended on Fe(II) and Fe(III) concentrations. The higher the concentration of iron(II) (up to 5 wt %) in the solution was, the higher conversion degree was achieved. A reverse relationship was observed concerning the influence of iron(III) introduced up to 1.5 wt %. The constant rates of both phases of titanyl sulfate hydrolysis (including the formation of an intermediate colloidal TiO2 and final products) depended on iron(II) and iron(III) content in the solution. The concentration of other constituents did not influence hydrolysis in the investigated part of the process (up to 2.6 wt % of Mg and up to 0.3 wt % of Al). However, the size of primary particles of the obtained TiO2źnH2O did not depend on the content of the above-mentioned constituents in the solution

Julolidine or Fluorenone Based Push−Pull Dyes for Polymerization upon Soft Polychromatic Visible Light or Green Light

International audienceTwo push−pull dyes (a julolidine derivative DCJTB and a fluorenone-co-amino phenyl derivative h-B3FL), incorporated in multicomponent photoinitiating systems have been investigated for the cationic polymerization of epoxides or the radical polymerization of acrylates under visible light irradiations (household halogen lamp or green laser diode at 532 nm). The DCJTB/iodonium salt (and optionally Nvinylcarbazole) based systems are pretty efficient for the cationic polymerization of epoxides. Both dyes, when combining with an amine and 2,4,6-tris(trichloromethyl)- 1,3,5-triazine, exhibit a good efficiency in the radical polymerization of acrylates. The photochemical mechanisms are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin trapping technique

Blue Light Sensitive Dyes for Various Photopolymerization Reactions: Naphthalimide and Naphthalic Anhydride Derivatives

International audienceNovel naphthalimide derivatives (or naphthalic anhydride derivatives) have been prepared and combined with an iodonium salt, Nvinylcarbazole, amines or 2,4,6-tris(trichloromethyl)-1,3,5-triazine to produce radicals and cations upon exposure to low intensity blue lights (e.g., a household blue LED bulb). The photochemical mechanisms are studied by electron spin resonance spin trapping, fluorescence, cyclic voltammetry, laser flash photolysis, and steady state photolysis techniques. The naphthalimide derivatives (ND4) or the naphthalic anhydride derivative (ND10) based photoinitiating systems are particularly efficient for cationic, radical and thiol− ene photopolymerizations; the synthesis of interpenetrated polymer networks IPNs can also be easily carried out. Compared to camphorquinone/amine or camphorquinone/iodonium salt, the new proposed combinations appear as highly versatile and high performance visible light photoinitiating systems. Some of these photoinitiating systems can also be used for UV LED irradiations (e.g., 365, 385, or 395 nm)

Structural Effects in the Indanedione Skeleton for the Design of Low Intensity 300−500 nm Light Sensitive Initiators

International audienceNewly synthesized indanedione derivatives combined with an iodonium salt, N-vinylcarbazole, amine, phenacyl bromide, or 2,4,6-tris- (trichloromethyl)-1,3,5-triazine have been used as photoinitiating systems upon very low visible light intensities: blue lights (e.g., household blue LED bulb at 462 nm) or even a halogen lamp exposure. One of them (ID2) is particularly efficient for cationic, radical and thiol−ene photopolymerizations as well as for the synthesis of interpenetrated polymer networks (IPNs). It can be useful to overcome the oxygen inhibition. ID2 based photoinitiating systems can also be selected for the reduction of Ag+ and the in situ formation of Ag(0) nanoparticles in the synthesized polymers. The (photo)chemical mechanisms are studied by electron spin resonance spin trapping, fluorescence, cyclic voltammetry, laser flash photolysis, and steady state photolysis techniques