Thermochimica Acta 515 (2011) 1–5 Contents lists available at ScienceDirect Thermochimica Acta journal homepage: www.elsevier.com/locate/tca Preparation and thermal properties of polystyrene/silica nanocomposites O. Bera a,∗ , B. Pili ´ c a , J. Pavliˇ cevi ´ c a , M. Joviˇ ci´ c a , B. Holló b , K. Mészáros Szécsényi b , M. ˇ Spirkova c a Faculty of Technology, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia b Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovi´ ca 3, 2100 Novi Sad, Serbia c Institute of Macromolecular Chemistry AS CR v.v.i., Heyrovskeho Nam. 2, 16206 Prague, Czech Republic article info Article history: Received 3 August 2010 Received in revised form 7 October 2010 Accepted 13 December 2010 Available online 21 December 2010 Keywords: Polystyrene Silica Nanocomposites Glass transition Thermal degradation Thermal stability abstract A series of polystyrene/silica nanocomposites with different inorganic nanoﬁller content were prepared by evaporating of toluene solvent. The weight fraction of silica nanoparticles of an average diame- ter of 7 nm treated with hexamethyldisilazane was varied (2, 5, 10, 15 and 30 wt.%). The polystyrene nanocomposite morphology was studied by scanning electron microscopy. The thermal stability of the samples was determined using thermogravimetry, coupled with differential scanning calorimetry. The inﬂuence of the ﬁller content on glass transition temperature of polystyrene/silica nanocomposites was followed by differential scanning calorimetry. It was found that the polystyrene glass transition temper- ature was inﬂuenced by the hydrophobic silica content. A mathematical method to describe the glass transition temperature dependence on the polystyrene/silica ratio is proposed. According to the experi- mental results and calculations, the highest thermal stability of the nanocomposite belongs to 18% silica content. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Polymer nanocomposites are a novel class of composites derived from the ultraﬁne inorganic particles with large surface area per volume unit and dimensions with a typical range of 1–1000 nm, dispersed in the polymer matrix [1,2]. Organic/inorganic compos- ite materials combine the advantages of the inorganic materials such as rigidity, hardness, durability, thermal stability and those of the organic polymers (ﬂexibility and processability). Due to the unique properties, these types of materials have attracted strong interest in many industrial processes [3]. The potential applications of polymer nanocomposites are coatings, ﬂame retardant materials, optical devices, electronical and optical packaging materials, etc. [4–6]. A lot of works deals with various types of nanosized ﬁllers and various methods of polymer/nanocomposites technology [7–11]. Among the numerous organic/inorganic nanocomposites the preparation, characterization, properties and applications of polystyrene/silica systems have been reported as a great area of active research [1,12]. The dispersion of nanometer-sized particles in the polymer matrix has a signiﬁcant impact on the properties of nanocomposites. A variety of methods have been used to enhance the compatibility between the hydrophobic polystyrene and sil- ica. The most frequently used method is to modify the surface of silica nanoparticles either by chemical or physical methods. The ∗ Corresponding author. Tel.: +381 214853738; fax: +381 21450413. E-mail address: oskarbera@gmail.com (O. Bera). extremely large surface area and smooth nonporous surface of sil- ica nanoparticles can intensify the effect of particle–particle and/or polymer–particle interactions, which could promote strong phys- ical contact between the silica and the polystyrene [13,14]. The loading of inorganic particles within polymers is usually performed by a wide range of methods, but unfortunately the simple mix- ing of organic and inorganic components at the macroscopic level is energy consuming and usually not very successful [1]. Thermal stability is considered as an important factor from the scientiﬁc and industrial point of view, playing role in the nanocomposite structure and morphology formation [15]. A better understand- ing of polymer degradation gives valuable data on the period of the applicability time of the material [16]. It has been shown that the thermal behavior of polymer nanocomposites depends on the nanoﬁller type and content [17,18]. One of the properties of a poly- mer, which can be profoundly affected by nanoparticles, is the glass transition temperature T g . It has been reported that polymers T g can be changed by the addition of nanoﬁller [19,20]. The temper- ature range of the availability of hybrid materials depends, among others, on their glass transition temperature. Therefore, it is of a great importance to develop a method to predict the T g of a new material [21,22]. In this paper a simple method for nanocompos- ite preparation in solution [23] was applied to prepare a series of polystyrene/silica nanocomposite materials. In order to improve nanocomposite homogeneity, silica with chemically modiﬁed sur- face was dispersed by ultrasonic treatment. The aim of the work was to study the inﬂuence of different silica content on thermal properties of polystyrene hybrid materials prepared in the form 0040-6031/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.tca.2010.12.006