In recent times, high-temperature polymer electrolyte membranes (HTPEMs) have emerged as viable alternatives to the Nafion-based low-temperature-operated polymer electrolyte membrane fuel cells. This is owing to their higher tolerance to fuel impurities, efficient water management, and higher cathode kinetics. However, the most efficacious HTPEMs such as poly(benzimidazole) (PBI) or 2,5-poly(benzimidazole) (ABPBI), which rely on the extent of phosphoric acid (PA) doping level for fuel cell performance, suffer from poor mechanical properties at higher acid doping levels and dopant leaching during continuous operation. To overcome these issues, we report the synthesis of ABPBI membranes and fabrication of ABPBI−zirconium pyrophosphate (α-ZrP)-based nanocomposite membranes by an ex situ methodology using methane sulfonic acid as the solvent. The incorporation of hydrophilic α-ZrP into the membrane resulted in higher dopability of PA (6.5 mol) and proton conductivity (46 mS/cm) of the membranes (10 wt % of α-ZrP) as against the corresponding values of 3.6 mol and 27 mS/cm, respectively, for the pristine membrane. More remarkably, these property improvements could be achieved while simultaneously augmenting the thermomechanical properties and oxidative stability of the membranes. The unit-cell tests showed a marked improvement in the maximum power density for the nanocomposite membrane (335 mW/cm 2 at 10 wt % α-ZrP content) over the pristine ABPBI membrane (200 mW/cm 2 ). We also report for the first time the feasibility of a 100 W HTPEM fuel cell (HTPEMFC) stack operated with the nanocomposite membrane with an active area of 39 cm 2 . The HTPEMFC stack delivered a stable voltage and power output, with a voltage drop rate of 0.84 μV/h over a run time of 730 h.

A polyvinyl alcohol/acrylamide based photopolymer composition that can be used to record holograms (at 532 nm) with ~92% diffraction efficiency and stability extending over a period of several months has been prepared. This system has been investigated earlier but with limitations of diminishing grating efficiency as a function of time and humidity. In the present work, we have successfully addressed these problems. In this work, crosslinkers have been added both for monomer and binder, and the effect of this addition and concentrations of various components of the composition on the diffraction efficiency and recording energy has been studied. It was found that an optimum concentration exists for each component at which diffraction efficiency is the maximum and recording energy the minimum. It was also observed that addition of a crosslinking monomer improved the grating efficiency. Crosslinking of the binder further improved the grating efficiency and its stability over time and under high humidity conditions. Maximum possible resolution for this photopolymer has been found to be 2000 lines/mm. Copyright © 2011 John Wiley & Sons, Ltd.