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4722759 
Journal Article 
Fast Proton Conduction Facilitated by Minimum Water in a Series of Divinylsilyl-11-silicotungstic. Acid-co-Butyl Acrylate-co-Hexanediol Diacrylate Polymers 
Horan, JL; Lingutla, A; Ren, Hui; Kuo, MeiC; Sachdeva, S; Yang, Y; Seifert, S; Greenlee, LF; Yandrasits, MA; Hamrock, SJ; Frey, MH; Herring, AM 
2014 
Yes 
Journal of Physical Chemistry C
ISSN: 1932-7447
EISSN: 1932-7455 
118 
1 
135-144 
WOS:000329678200017 
Studies of proton transport in novel materials are important to enable a large array of electrochemical devices. In this study, we show that heteropoly acids (HPAs) when immobilized in polymer matrixes have highly mobile protons. Divinyl-11-silicotungstic acid, an HPA, was copolymerized with butyl acrylate and hexanediol diacrylate at various weight percentage loadings from 25% to 85% using UV initiated polymerizations. The resultant films were tan colored flexible sheets of ca. 120 mu m thickness. The morphology of these films varied with loading, showing phase separation into clustered HPA above a 50 wt % loading and lamella morphologies above an 80 wt % loading. Water uptake was strongly associated with the HPA clusters, which facilitated transport of protons. This was realized by proton conductivities as high as 0.4 S cm(-1) at 95 degrees C and 95% RH and 0.1 S cm(-1) at 85 degrees C and 50% RH. Pulse field gradient spin echo NMR measurements indicated that water self-diffusion was fast (1.4 x 10(-5) and 4.4 x 10(-5) cm(2) s(-1) for 50% and 100% RH, respectively) at 80 degrees C. We show that the water in these systems is highly associated with the HPA clusters and that fast proton transport is facilitated by as few as 3 water molecules per proton.