Solid State Ionics 127 (2000) 133–139 www.elsevier.com / locate / ssi Antimonic acid and sulfonated polystyrene proton-conducting polymeric composites a, a a b b b * J.M. Amarilla , R.M. Rojas , J.M. Rojo , M.J. Cubillo , A. Linares , J.L. Acosta a Instituto de Ciencia de Materiales de Madrid ( CSIC), Cantoblanco, 28049 Madrid, Spain b ´ ´ Instituto de Ciencia y Tecnologıa de Polımeros ( CSIC), C / Juan de la Cierva 3, 28006 Madrid, Spain Received 16 March 1999; received in revised form 13 August 1999; accepted 23 September 1999 Abstract Polymer composites formed of a proton conductor and polyvinylidene fluoride (PVDF) are prepared. Sulfonated polystyrene (SPS) and antimonic acid (AAc) are used as organic and inorganic proton conductor, respectively. PVDF is the insulating matrix used as a binder to improve the mechanical stability of the composites compared with the pure proton conductors. The effect of the SPS and / or AAc on both the glass transition temperature, T , and the melting temperature, T , g m of the PVDF is studied. The ionic conductivity of the composites, after water vapor exposure at r.t., and after water immersion at 508C, is measured at room temperature. The overall conductivity of the composite increases with time up to saturation, which is attained: (i) after 17 h for the water vapor exposure experiment and (ii) after ¯ 10 min, for the water immersion experiment. The ionic conductivity of the composites is smaller than that of the pure protonic conductors, but the composites show high-dimensional stability. The shape of the conductivity curve depends on the proton conductor chosen.  2000 Elsevier Science B.V. All rights reserved. Keywords: Ionic conductor composite; Proton conductor; Composite; Antimonic acid; Sulfonated polystyrene; Solid electrolyte PACS: 66.10.Ed 1. Introduction combine a good ionic conductivity with high chemi- cal, mechanical and thermal stability. To improve Proton conductors are interesting materials due to protonic conductivity some polymeric membranes their potential application as solid electrolyte in ionic have been sulfonated [5–7], and to improve me- devices such as fuel cell, batteries, electrochromic chanical stability composites formed of a proton glasses, etc. [1,2]. At present, polymer electrolyte conductor and an insulating polymeric matrix have membrane fuel cells (PEMFCs) have gained great been tried [8,9]. Within this scope we have prepared interest as a promising power source for environmen- new proton-conducting composites based on an tally acceptable electric buses and cars [3,4]. The organic (sulfonated polystyrene) or inorganic (an- solid electrolytes suitable for these cells should timonic acid) proton-conducting compound, and an insulating polymeric matrix (polyvinylidene fluo- *Corresponding author. ride). Antimonic acid with pyrochlore-like structure 0167-2738 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0167-2738(99)00278-7