Contents lists available at ScienceDirect Solid State Ionics journal homepage: www.elsevier.com/locate/ssi Properties of anion exchange membrane based on polyamine: Effect of functionalized silica particles prepared by sol–gel method Narges Ataollahi a, ⁎ , Elisa Cappelletto a , Keti Vezzù b , Vito Di Noto b,c , Gianni Cavinato d , Emanuela Callone e , Sandra Dirè e , Paolo Scardi a , Rosa Di Maggio a a Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy b Section of Chemistry for Technology, Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy c Institute of Condensed Matter Chemistry and Technologies for Energy (CNR-ICMATE), Via Marzolo 1, 35131 Padova, PD, Italy d Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, PD, Italy e “Klaus Müller” Magnetic Resonance Lab., Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy ARTICLE INFO Keywords: Polyamine Modified silica Membrane NMR ABSTRACT Membranes of polyamine (PA-SiNH 2 ) m , containing silica reacted with 3-aminopropyltriethoxysilane (APTES) in hydrolytic conditions were prepared via solution casting, followed by methylation and ion exchange process. The influence of amino-functionalized silica (Si-NH 2 ) on the properties of the obtained membrane was investigated. Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance spectroscopy (NMR) were used to investigate the chemical features of the silica and its interaction with the polyamine polymer. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the modified membrane confirmed it is stable up to 300 °C. The thermal stability is the result of the interaction of modified silica particles and polyamine polymer. It was demonstrated that the performance of the (PA-SiNH 2 ) m anion exchange mem- brane is greatly improved by incorporation of silica nanoparticles as compared with the anion exchange membrane (PK-PDAPm), which doesn't contain silica. Therefore, the (PA-SiNH 2 ) m is a suitable candidate for electrochemical applications. 1. Introduction The main goal of this study is to obtain a new polymeric material in which amino-functionalized silica (Si-NH 2 ) contributes in a synergic way to the performance of the final composite, increasing both anion exchange properties and thermal stability. This goal could be reached by surface modification of inorganic nanoparticles, which is of big interest due to the wide range of potential applications in the fields of chemistry, biology and physics including composite materials [1] drug delivery [2], coupling and immobilization of functional molecules and biomolecules [3] base-catalysis [4]. Moreover, the surface modification of inorganic nanoparticles leads to enhance the compatibility between organic and inorganic phases [5]. Metal oxides such as SiO 2 have been widely used as inorganic fillers in polymer composites [6–8]. This is due to the commercial availability of a wide range of particle size and morphology, the large number of surface hydroxyl groups suitable for further modification and finally the ease of in situ silica formation by the sol-gel process of silicon alkoxides under mild conditions [9,10]. Silica addition was also proved to strengthen the interface between nanoparticles and polymer matrices [11,12]. Basically, the functionalization of silica particle is a method for tailoring the surface properties of particles to fit the target applications [13,14] and 3-aminopropyltriethoxysilane (APTES) is often used if the aim is to insert anionic groups [15–18]. Recently, our research group reported the preparation of anion ex- change membrane based on polyamine (PK-PDAPm), prepared by the modification of polyketone (PK) skeleton [19]. The polyamine consists of a stable pyrrole ring along the backbone, and a reactive pendant amino functional group [19]. In the present work, the hydroxyl groups of silica powder were exploited for the condensation reaction with 3- APTES under hydrolytic conditions [20–22], and the modified silica (Si- NH 2 ) was added to polyamine. It is expected that the amino functional groups (Si-NH 2 ), incorporated into the polyamine membrane, lead to a stable, homogeneous reinforcement effect by improving the filler- polymer interface, and, in turn, help in achieving improved ionic ex- change capacity (IEC). As a consequence, the incorporation of Si-NH 2 within polyamine membranes to form (PA-SiNH 2 )m, should help to increase its conductivity, maintain water retention at high temperatures https://doi.org/10.1016/j.ssi.2018.04.022 Received 15 September 2017; Received in revised form 10 March 2018; Accepted 27 April 2018 ⁎ Corresponding author. E-mail address: narges.ataollahi@unitn.it (N. Ataollahi). Solid State Ionics 322 (2018) 85–92 0167-2738/ © 2018 Elsevier B.V. All rights reserved. T