Functionalized Nanoparticles for Composite Polymer Electrolyte
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1006-R05-02
Functionalized Nanoparticles for Composite Polymer Electrolyte Gilles Toussaint, Catherine Henrist, Christophe Detrembleur, Robert Jerome, and Rudi Cloots Chemistry, University of Liege, Allee de la chimie, batiment b6a, Liege, 4000, Belgium ABSTRACT The covalent grafting of low-molecular weight poly(ethylene glycol) (PEG) onto high surface silica nanoparticles (Cab-O-Sil EH5) has been accomplished by a multi-step reaction. Reaction involved PEG attachment by epoxide-terminated ring opening of a sylilation agent previously grafted. A maximum grafting density of 0.42 PEG per nm≤ has been determined by thermogravimetric analysis (TGA). Differential scanning (DSC) calorimetry confirmed the modification of silica after reaction. Infra-Red (IR) analysis and Carbon-13 Magic Angle Spinning Nuclear Magnetic Resonance (13C MAS NMR) confirmed PEG fixation and opening of the epoxide ring. INTRODUCTION Polymer nanocomposites have been an area of intense industrial and academic research for the past 20 years. Compared to microcomposites, nanocomposites can have similar or improved properties with substantially less filler [1]. These properties strongly depend on filler size [2] and dispersion, which indeed result from the interaction between the matrix host and the very high specific surface of nanofillers [3]. Polymer brushes, resulting from polymer attachment to solid surface, have proven to be an effective method for altering the interaction of solids with their environment [4]. Poly(ethylene oxide) (PEO) and poly(ethylene glycol) (PEG) have biocompatible and hydrophilic properties making them interesting for medical and biologic applications (5). As reported by Sheardown and coworkers [6], covalent attachment of PEO on PDMS surface decreased the undesirable protein adsorption effect due to the high protein affinity of PDMS. Moreover, PEO-based electrolytes are still extensively studied as polymer ionic conductor for lithium batteries, but a high crystalline phase concentration limits their conductivity [7]. Nanofillers increase electrolyte mechanical properties, give better interfacial compatibility with electrodes [8], and can interact with polymer chains-lithium system [9]. Therefore, in order to further investigate the dispersion of surface modified fillers in PEO electrolyte, this work describes a method used to covalently graft PEG onto silica nanoparticles. EXPERIMENTAL DETAILS Cab-O-Sil EH5 fumed silica (Cabot Corporation) has a specific surface of 380 m≤/g, 4 OH groups / nm≤ and is made of nanoparticles arranged in a non-porous three-dimensional branched chain aggregates. Tetrahydrofuran (THF) and toluene used for reaction were dried over sodium for a night. Methoxypoly(ethylene glycol) 350 (PEG, Mw = 350, Aldrich) was dried by three successive azeotropic distillations with toluene. 3-glycidoxypropyl trimethoxysilane (GPS, Gelest) and dry sodium hydride 95% (Aldrich) were used as received. Technical grade toluene and isopropanol were used for washing procedure. Glassware was heated under vacuum to remove
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