Polyethylene glycol/clay nanotubes composites Thermal properties and structure G. Cavallaro • R. De Lisi • G. Lazzara • S. Milioto Received: 18 July 2012 / Accepted: 12 October 2012 / Published online: 7 November 2012 Ó Akade ´miai Kiado ´, Budapest, Hungary 2012 Abstract Nanocomposites of poly(ethylene) glycol (PEG) 20000 filled with clay nanotubes (HNTs) were prepared. The thermal properties obtained from thermo- gravimetry and differential scanning calorimetry were correlated to the morphology imaged by scanning electron microscopy. Low amounts of HNTs generate compact structure while large amounts of HNTs create craters and voids. The decrease of polymer degradation temperature in the presence of large amount of nanoclay (ca. 80 wt%) is a consequence of the morphology at the mesoscale range. The thermal opposite effect observed in the HNTs low regime (up to ca. 20 wt%) is due to the gas entrapment into the nanoparticles lumen. The quantitative analysis of the PEG 20000 enthalpy of melting in the presence of HNTs allowed us to characterize the polymer adsorption onto the nanoclay surface. Keywords Halloysite  Nanotube  PEG  Nanocomposite  TG  SEM  DSC Introduction Polymer–nanoclay composites are well known in the nanotechnology and engineering fields. These nanomate- rials have attracted increased interest in recent years because of their improved properties with respect to the pristine polymer, and therefore, their designing may be a challenging task for applications in several fields. Batteries, [1] packaging films [2] and membranes for proton exchange [3] are some examples of potential applications. In general, thermal properties of materials are crucial to establish their use in a certain field; a recent review [4] reported that several polymeric materials are disadvanta- geous because of fast degradation. Filling polymers with nanoclays may be a proper strategy to obtain a thermal stabilization of a polymer and it may produce new nanomaterials with tunable properties [5]. Among nanoclays, halloysite nanotubes (HNTs) are newly emerging fillers with interesting properties [6] and appealing perspectives [7]. Halloysite is a non-toxic [8] natural alluminosilicate with an unitary cell composed of Al 2 Si 2 O 5 (OH) 4 2H 2 O and a peculiar hollow tubular shape (the outer and inner diameters are ca. 30–50 and 1–30 nm, respectively) [6]. Cancer cell separation, bone implants, cosmetics, and controlled drug delivery [9] are interesting examples of HNTs medical applications. Well-dispersed HNTs into polypropylene [10] and polyamide [11] deter- mined a thermal stabilization and a mechanical reinforce- ment of the polymer matrix. The macromolecule nature and the amount of filler play a key role on both the physico- chemical properties of nanocomposites and their morphol- ogy [2, 12]. In this study, we investigated poly(ethylene) glycol (PEG) as polymeric matrix that is well known for its several applications and biocompatibility [13]. Keeping in mind [14] that PEGs may be used as consolidants of archaeological woods, their filling with HNTs may generate new advanced nanomaterials for Cultural Heritage applica- tions. Moreover, the HNTs ability to entrap chemical species into the lumen was exploited to design anticorrosive films for metal protection [7]. Electronic supplementary material The online version of this article (doi:10.1007/s10973-012-2766-8) contains supplementary material, which is available to authorized users. G. Cavallaro (&)  R. De Lisi  G. Lazzara  S. Milioto Dipartimento di Chimica ‘‘S. Cannizzaro’’, Universita ` degli Studi di Palermo, Viale delle Scienze pad. 17, 90128 Palermo, Italy e-mail: giuseppe.cavallaro@unipa.it 123 J Therm Anal Calorim (2013) 112:383–389 DOI 10.1007/s10973-012-2766-8