ORIGINAL PAPER Inﬂuence of a non-polar medium (alkane and molten polypropylene) on the titanium n-butoxide hydrolysis-condensation reactions Walid Bahloul • Ve ´ronique Bounor-Legare ´ • Ge ´rard Seytre • Philippe Cassagnau Received: 28 June 2010 / Accepted: 28 August 2010 / Published online: 16 September 2010 Ó Springer Science+Business Media, LLC 2010 Abstract Study of hydrolysis-condensation reactions of titanium n-butoxide precursor into an unusual medium and non-classical conditions was carried out. Kinetic data were reached in a temperature range of 130–250°C from FTIR, TGA–GC–MS and rheological techniques. These results were obtained into an alkane dispersing medium, (Squa- lane: 2,6,10,15,19,23-hexamethyltetracosane), and compared to the ones determined from the hydrolysis-condensation reactions of the titanium dioxide precursor carried in molten polypropylene (PP) during extrusion process. The transpo- sition of these knowledge to the in situ synthesis of titanium dioxide in molten PP matrix by reactive extrusion lead to the formation of a ﬁne dispersion of few nanometer diameter (*5 nm) of TiO 2 particles. Finally, the viscoelastic behav- iour of the nanocomposite has been strongly altered in the terminal relaxation zone as permanent secondary plateau (solid-like behavior), attributed to some fractal arrangement of the inorganic domains was observed. Keywords Titanium n-butoxide  Hydrolysis-condensation reactions  Reactive extrusion  In situ synthesis  Non-polar medium  Polypropylene 1 Introduction An original way to prepare polymer nanocomposite is the in situ synthesis of the inorganic ﬁller in polymer matrix by sol–gel methods. The sol–gel process [1–5] based upon hydrolysis-condensation reactions of the metal alkoxide, leads to an inorganic network that causes the precipitation and dispersion of inorganic ﬁllers throughout the polymer matrix. For example, the sol–gel method has already been reported for the preparation of nanocomposites based sili- cone rubber [6, 7], polyisobutylene [8], several diene rub- bers [9–14] and recently polyoleﬁns [15, 16]. Concerning the nature of the inorganic ﬁller created, titanium alkoxides are the most convenient and most described inorganic precursors used to get titanium dioxide with controlled purity and morphology through these hydrolysis-condensation reactions [17, 18]. However, due to their strong sensitivity to water, several reaction param- eters in solution have been used to control the kinetics such as pH, H 2 O/Ti ratio, size of ligands or chemical modiﬁca- tions to introduce less hydrolysable groups [19, 20]. For example, Barringer et al. [21] studied the reaction mechanism and kinetics for Ti(OC 2 H 5 ) 4 as inorganic pre- cursor and depending of the H 2 O/Ti ratio. Kallala et al. [22] studied the growth of oxopolymers formed from Ti(OC 2 H 5 ) 4 in condensation steps under various experi- mental conditions. Terable et al. [23] have evidenced the inﬂuence of the experimental synthesis conditions (pH, H 2 O/alkoxide ratio) on the number of unhydrolysed alkoxy groups and, consequently, on the gel crystallization. In that frame, the tools developed to monitor these kinetics are also well documented. Burgos et al. [24] studies the sol–gel transformation of titanium isopropoxide coatings by FTIR. They revealed the inﬂuence of the solvent and pointed out the assignment of the main absorbance bands during the reactions. Guilment et al. [25] provided many data on the ﬁrst steps of sol–gel process with FT-Raman spectroscopy. Rheological measurements are complementary to spectro- scopic experiments and are sensitive to structural and W. Bahloul  V. Bounor-Legare ´(&)  G. Seytre  P. Cassagnau Inge ´nierie des Mate ´riaux Polyme `res: Laboratoire des Mate ´riaux Polyme `res et Biomate ´riaux, Universite ´ de Lyon, Universite ´ de Lyon 1, CNRS UMR5223, 15 Boulevard Latarjet, 69622 Villeurbanne, France e-mail: Veronique.bounor-legare@univ-lyon1.fr 123 J Sol-Gel Sci Technol (2011) 57:86–94 DOI 10.1007/s10971-010-2327-1