Application of electro-spray ionization mass spectrometry for characterization of titanium polyoxoalkoxides in sol-gel processes

Excerpt

Sol-gel derived titanium dioxide nanoparticles with controlled size distribution and morphology are of great interest for different applications [1]. Understanding the phenomena occurring during the initial stage of particle growth is especially important, because they determine the properties of the final products (powders, films, gels). The titania sol-gel polymerization follows essentially a different pathway than the relatively well studied silicon based sol-gel process [2]. Generally, in the silicon case, individual monosilicate serves as building units during the process, while in the titania polymerization the role of building blocks can be played by polyoxoalcoxides (titanium oxide clusters) [2‐4]. Particularly Ti₁₁O₁₃(OC₃H₇)₁₈ was proposed as such a building block in the case of titanium isopropoxide (TTIP) based sol-gel process [3]. A stable solution of these clusters can be obtained by hydrolysis of TTIP under low hydrolysis ratios H < 1 (H is the molar ratio of water and alkoxide). It can be analyzed e.g. by O¹⁷ NMR spectroscopy [4]. …