Issue 38, 2011

Polybenzimidazole/silica nanocomposites: Organic-inorganic hybrid membranes for PEMfuel cell

Abstract

Despite the myriad studies on polybenzimidazole based polymer electrolyte membranes for fuel cells operating above 100 °C, the development of membranes with higher proton conductivity without compromising mechanical stability has continued to be the prime challenge. In this article, organic/inorganic hybrid nanocomposites of poly (4,4′-diphenylether-5,5′-bibenzimidazole) (OPBI) were prepared with surface functionalized silica nanoparticles to address this key issue. Structural and morphological studies probed by SAXS, WAXD and TEM, respectively revealed the formation of self-assembled clusters of nanoparticles when the OPBI nanocomposites were made with amine modified silica (AMS) whereas a well dispersed structure was obtained for OPBI and the unmodified silica (UMS) composite. The OPBI/AMS nanocomposites displayed a significant enhancement in the thermal stabilities compared to the pristine OPBI and OPBI/UMS nanocomposite. The OPBI/AMS nanocomposite membranes exhibited a larger mechanical reinforcement than the pristine OPBI and OPBI/UMS nanocomposite. The formation of nanoparticle clusters in the OPBI matrix in the case of OPBI/AMS was found to be the driving force for the higher thermal and mechanical stability of OPBI/AMS than those of OPBI/UMS. The incorporation of AMS in the OPBI matrix shielded the polymer chains from the attack of oxidative radicals, resulting in a huge enhancement of oxidative stability of the nanocomposite membranes compared to the pure OPBI membrane. The OPBI/AMS nanocomposite membranes have significantly higher phosphoric acid (PA) loading compared to the pure OPBI membrane which resulted in the higher proton conductivities of the former. The self-assembled clusters of AMS in the OPBI matrix facilitated the proton transport process.

Graphical abstract: Polybenzimidazole/silica nanocomposites: Organic-inorganic hybrid membranes for PEM fuel cell

Supplementary files

Article information

Article type
Paper
Submitted
16 May 2011
Accepted
11 Jul 2011
First published
19 Aug 2011

J. Mater. Chem., 2011,21, 14897-14906

Polybenzimidazole/silica nanocomposites: Organic-inorganic hybrid membranes for PEM fuel cell

S. Ghosh, S. Maity and T. Jana, J. Mater. Chem., 2011, 21, 14897 DOI: 10.1039/C1JM12169C

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