In situ implantation of PolyPOSS blocks in Nafion® matrix to promote its performance in direct methanol fuel cell

Abstract

Fabrication of recast Nafion®-117 membrane using the dipolar aprotonic solvent will normally lead to a random matrix. On the contrary, when a designed amount of vinyl-pendant octasiloxane (Q8M8 V) cubic molecules was included into the Nafion® matrix during the recasting process and then subjected to polymerization, a nonrandom matrix was obtained. This paper provides an insight into the matrix-formatting role of rigid poly(Q8M8 V) blocks, generated in situ in Nafion® matrix, according to thermal analyses (thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and Differential Scanning Calorimetry (DSC)) and electron microscopic images of the resulting composite matrix. The P(Q8M8 V) played a role in restricting random extensions of proton-conducting channels (PCCs) and promoted ordered assembling of Nafion® molecules. As a result, compared with the recast pristine Nafion® membrane, the composite membranes containing P(Q8M8 V) of 5-15 wt.% manifested obvious improvement on both repression of methanol permeability and promotion of power density output of the single direct methanol fuel cell (DMFC). © 2008 Elsevier B.V. All rights reserved.