Spectroscopic characterization of GPTMS/DETA and GPTMS/EDA hybrid polymers Marija R. Gizdavic-Nikolaidis * , Zoran D. Zujovic, Neil R. Edmonds, Clive J. Bolt, Allan J. Easteal Department of Chemistry, The University of Auckland, Private Bag 92019, Auckland, New Zealand Received 16 June 2006; received in revised form 17 January 2007 Available online 23 March 2007 Abstract Silica/epoxy hybrid polymers were synthesized from 3-glycidoxypropyltrimethoxysilane (GPTMS) by hydrolysis of the silane func- tional groups at a range of pHs and water contents of the reaction mixtures, followed by crosslinking by ring opening of the epoxy groups using diethylenetriamine (DETA) or ethylenediamine (EDA). The GPTMS/DETA and GPTMS/EDA hybrid polymers were formed to an extent determined by the mole ratio of active hydrogens from the diamine to epoxy rings (R H ). Structural characterization of the hybrid polymers was performed using Scanning Electron Microscopy (SEM), and Raman, and 13 C and 29 Si Solid-State Nuclear Magnetic Resonance (NMR) spectroscopies. The results showed that extensive crosslinking occurred for GPTMS/DETA and GPTMS/ EDA rigid, homogeneous hybrids with R H = 1, particularly at pH 10. Ó 2007 Elsevier B.V. All rights reserved. PACS: 81.07.Pr; 82.56.b; 87.64.Ee Keywords: Organic–inorganic hybrids 1. Introduction Inorganic–organic hybrids are interesting materials for their potential wide range of applications, particularly in composites and coatings [1–7] as they can provide the pro- cessability, flexibility, toughness and durability of organic polymers with the abrasion resistance, hardness, chemical resistance, weatherability and UV-resistance of inorganic silicate polymers. The inorganic and organic networks are formed, often simultaneously, to achieve homogeneous phase morphologies. One way of obtaining stronger inter- action between the inorganic and organic components is to use functionalised silanes as crosslinkers, and an impor- tant class of inorganic–organic hybrid materials is based on the coupling agent 3-glycidoxypropyltrimethoxysilane (GPTMS), which has been reported to form both a silicate network and an organic epoxy network at low pH [1–6,8]. The GPTMS molecule has six carbon atoms, labelled a–f (the carbon atoms are identified in Scheme 1a). Hydrolysis of the methoxy groups gives silanol groups which can subsequently condense to form a silicate net- work [8,9]. Crosslinks between the inorganic and organic networks arise either from the pre-existing link in the GPTMS molecule, by direct reaction of silanols with epoxy rings, or by condensation of silanols with hydroxyls from the opened epoxy rings. Epoxy ring opening and organic network formation can be achieved by the use of curing agent such as diethylenetriamine (DETA, Scheme 1b) or ethylenediamine (EDA, Scheme 1c) at room temperature. Each active hydrogen in the –NH or –NH 2 groups of the amine is capable of opening and linking to one epoxy group of GPTMS. The nitrogen of the amine enters into the organic network and the branching of the network 0022-3093/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2007.01.035 * Corresponding author. Tel.: +64 9 373 7599x89424; fax: +64 9 373 7422. E-mail address: m.gizdavic@auckland.ac.nz (M.R. Gizdavic-Nikolai- dis). www.elsevier.com/locate/jnoncrysol Journal of Non-Crystalline Solids 353 (2007) 1598–1605