Poly(methyl methacrylate-maleic anhydride) (P(MMA-MAh)) has been synthesized from methyl methacrylate (MMA) and maleic anhydride (MAh) monomers. The molar ratio of monomers was found to be 1MAh:8MMA. The molecular weight of copolymer was determined in the order 10(4) (g/mol). Rectorite modified with dodecyl benzyl dimethyl ammonium chloride (OREC) was used as a filler additive to modify gel polymer electrolytes (GPEs) which consisted of P(MMA-MAh) used as polymer matrix, propylene carbonate (PC) as a plasticizer and LiClO4 as lithium ion producer. Characterization of interaction of C=O in PC and copolymer with Li+ and OH group on OREC surface has been thoroughly examined using FTIR. The quantitative analysis of FTIR shows that the absorptivity coefficient a of copolymer/LiClO4, PC/LiClO4, PC/OREC and copolymer/OREC is 0.756, 0.113, 0.430 and 0.602, respectively, which means that the Li+ or OH bonded C=O is more sensitive than free C=O in FTIR spectra. The limit value of bonded C=O equivalent fraction of copolymer/LiClO4, PC/LiClO4, PC/OREC and copolymer/OREC is 55, 94, 57 and 26%, respectively, which implies that all the interaction within the components is reversible and the intensity of interaction is ordered as PC/LiClO4, PC/OREC, copolymer/OREC and copolymer/LiClO4. (C) 2008 Elsevier Ltd. All rights reserved.