Please cite this article in press as: C.-D. Varganici, et al., Thermal degradation of magnetite nanoparticles with hydrophilic shell, J. Anal. Appl. Pyrol. (2012), doi:10.1016/j.jaap.2012.03.005 ARTICLE IN PRESS G Model JAAP-2731; No. of Pages 6 Journal of Analytical and Applied Pyrolysis xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Journal of Analytical and Applied Pyrolysis journa l h o me page: www.elsevier.com/locate/jaap Thermal degradation of magnetite nanoparticles with hydrophilic shell Cristian-Dragos Varganici a , Anamaria Durdureanu-Angheluta a , Dan Rosu a,∗ , Mariana Pinteala a , Bogdan C. Simionescu a,b a Centre of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry, 41A Gr. Ghica-Voda Alley, 700487 Iasi, Romania b Department of Natural and Synthetic Polymers, “Gh. Asachi” Technical University of Iasi, 73 B-dul Dimitrie Mangeron, 700050 Iasi, Romania a r t i c l e i n f o Article history: Received 28 November 2011 Accepted 11 March 2012 Available online xxx Keywords: Hybrid materials Thermogravimetric analysis Thermal degradation kinetics Evolved gas analysis a b s t r a c t The aim of this study was the investigation of thermal degradation process at the interface of a core–shell type structure. Such hybrid compound was comprised of an inorganic core of magnetite nanoparticles and an organic shell consisting of 3-aminopropyltriethoxysilane. The thermal degradation has been studied by thermogravimetry in nitrogen atmosphere, up to 500 ◦ C. The evolved gases analysis was performed using a coupling to a quadrupole mass spectrometer and a Fourier transform infrared spectrophotometer equipped with external modulus for gas analyses. Isoconversional kinetic study was conducted and a three stage thermal degradation mechanism was proposed. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The research field of coated magnetite nanoparticles as sub- strate in bionanoconjugates has been expanding for more than three decades because of their potential as drug carriers for tar- geted drug delivery [1,2]. Therefore the establishment of accurate thermokinetical decomposition mechanisms plays an important role in the industrial processing of the future drug, especially for drugs in the form of oral tablets and capsules. Along with the appropriate pressing pressure, the temperature program must be rigorously selected in order to induce the specific cohesion forces and disintegration time once the tablet or capsule has reached the digestive tract [3]. This aspect is of greater importance especially in the field of controlled drug delivery or targeting. Other biomed- ical applications of magnetite nanoparticles are based on their magnetic properties. Such applications are: magnetic-force-based tissue engineering, magnetic enhanced transfection, magnetically induced hyperthermia and magnetically assisted gene therapy [4,5]. The potential of drug delivery systems based on the use of mag- netite nanoparticles as drug carriers brings three major advantages: (i) the ability to localize and target specific locations in the body; (ii) a seemingly reduced quantity of the drug needed to maintain a certain concentration in the proximity of the target; and (iii) the minimizing of side effects due to a reduction in the concentration of the drug at nontarget sites [6,7]. ∗ Corresponding author. Tel.: +40 232 217 454; fax: +40 232 211 299. E-mail addresses: drosu@icmpp.ro, dan rosu50@yahoo.com (D. Rosu). The thermooxidative degradation kinetics of solely precipitated magnetite particles were studied elsewhere and their decomposi- tion into maghemite and hematite was reported [8–10]. The purpose of this paper is to obtain new knowledge and information about thermal stability of core–shell systems based on magnetite nanoparticles with polysiloxane coatings in inert atmo- sphere. 2. Experimental 2.1. Synthesis The synthesis of 3-aminopropyltriethoxysilane covered mag- netite nanoparticles M(III)APTES was submitted to a previous paper [11]. The existence of the core–shell structure as nanoparticles was proven by dynamic light scattering (DLS) technique and the diameters of the nanoparticles were found to be in the range 30–50 nm [11]. 2.2. Measurements The thermal degradation and evolved gas analyses of M(III)APTES were performed with a TGA-FTIR-MS system. The sys- tem was equipped with an apparatus of simultaneous TGA/DSC analyses STA 449F1 Jupiter model (Netzsch, Germany), FTIR spec- trophotometer Vertex-70 model (Bruker, Germany), and mass spectrometer QMS 403C Aëolos model (Netzsch, Germany). The TG/DSC thermobalance was coupled online with FTIR spectropho- tometer and mass spectrometer through two heated transfer lines. 9 mg were heated from 25 to 500 ◦ C under nitrogen flow (flow 0165-2370/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jaap.2012.03.005