Thermochimica Acta 439 (2005) 80–85 Thermal behaviour of polyoxocarbosilane shells in Fe-based (core)–polyoxocarbosilane (shell) nanocomposites A. Gal´ ıkov´ a a , Z. Bastl b , R. Alexandrescu c , I. Morjan c , J. Pola a,∗ a Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 6-Suchdol, 16502 Prague, Czech Republic b J. Heyrovsk´ y Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 18223 Prague, Czech Republic c National Institute for Lasers, Plasma and Radiation Physics, R-76900 Bucharest, Romania Received 16 May 2005; received in revised form 9 August 2005; accepted 5 September 2005 Available online 13 October 2005 Abstract Thermal behaviour of Fe-based (Fe/Fe 2 O 3 core)–polyoxocarbosilane (shell) nanocomposites, prepared by laser-induced co-decomposition of iron pentacarbonyl and hexamethyldisiloxane in the gas phase, was examined by using TGA technique. The thermal decomposition of the polymer shell of the nanocomposite is revealed as a two-stage (low- and high-temperature) evolution of methane. The importance of the low-temperature stage increases and that of the high-temperature stage decreases with increasing amount of the Fe/Fe 2 O 3 cores. The results represent the first thermal data related to nanocomposite metal/polymer system and are explained in terms of heterogeneous catalysis of the polyoxocarbosilane decomposition by the Fe/Fe 2 O 3 core. © 2005 Elsevier B.V. All rights reserved. Keywords: Thermal decomposition; Iron/polyoxocarbosilane nanocomposite; TGA; Heterogeneous effect 1. Introduction Iron- and iron oxide-based nanocomposite materials with iron or iron oxide nanoparticles separated by different insulating media as porous glass [1], mesoporous silica [2], silicon oxide [3] and various polymers [4–7] have been of great interest due to their superparamagnetic properties [8] and potential applica- tions in medical diagnostic technologies [9,10] and sensors and actuators systems [11–14]. The nanosized particles of iron stabilized by polymers were prepared by sonolysis of iron pentacarbonyl in the presence of poly(dimethylphenyleneoxide) [15] and those of iron oxide embedded in organic polymers were prepared by static cast- ing [16], ultrasound radiation [17], wet chemical approach [18], seed precipitation–polymerization in the presence of iron oxide nanoparticles [19], in situ oxidation of iron salts within poly- mer latex [20], and laser-induced formation of cationic particles acting as polymerization catalysts [21]. ∗ Corresponding author. Tel.: +420 2 20390308; fax: +420 2 20920661. E-mail address: pola@icpf.cas.cz (J. Pola). We have recently reported that IR laser ethylene-sensitized heating of gaseous iron pentacarbonyl-hexamethyldisiloxane [22,23] (or methoxytrimethylsilane, [24]) results in the forma- tion of nanosized iron-based particles that are covered with organosilicon polymer and which become superficially oxidized to Fe 2 O 3 through incomplete protection by or porous structure of the surrounding polymer. Having been produced at high- temperatures and incorporating -Fe 2 O 3 (and -Fe 2 O 3 ) in the outer core phase, these nanocomposites show ferromagnetic and superparamagnetic properties and high specific surface area and can be therefore promising as nanostructured magnetic ceramics [25] and high-temperature gas sensors [13]. These materials can also serve as an interesting model for examination of the effect of the Fe/Fe 2 O 3 core on the decompo- sition of the polymeric shell. Conventional thermal degradation of polymers is, in principle, affected (e.g. [26]) by ubiquitous heterogeneous, surface-catalyzed steps, whose real importance was recently manifested through achieving decomposition of several polymers upon irradiating them by using IR lasers (e.g. [27–29]). The examination of the organosilicon polymer degra- dation in the Fe/Fe 2 O 3 (core)/polyoxocarbosilane (shell) system can not only reveal the effect of the Fe/Fe 2 O 3 core on the mode 0040-6031/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.tca.2005.09.002