# Cross-linked PVA/PSSA-CNTs based polyelectrolyte membranes with enhanced proton conductivity for fuel cell applications

## TL;DR

This paper develops a new polyelectrolyte membrane with improved proton conductivity and mechanical strength for fuel cell applications.

## Contribution

A novel cross-linked PVA/PSSA-CNTs membrane is introduced, offering enhanced proton conductivity and reduced methanol crossover.

## Key findings

- The membrane shows a 60% improvement in tensile strength when PSSA@CNTs are added.
- The proton conductivity of the membrane reaches 6.12 × 10⁻² S·cm⁻¹.
- The membrane exhibits self-extinguishing properties and high thermal stability.

## Abstract

Developing polyelectrolyte membranes (PEMs) that possess optimal mechanical and electrochemical properties while maintaining economic efficiency for given applications is challenging. In this research, conductive Polystyrene sulfonic acid (PSSA) interacted with multi-walled carbon nanotubes symbolized (PSSA@CNTs) and incorporated into cross-linked Polyvinyl alcohol (PVA) to create a unique polyelectrolyte membrane. The solution casting procedure was used to prepare cross-linked PVA membranes using varying molar ratios of (PSSA@CNTs). The interaction of cross-linked PVA with PSSA@CNTs was established using different techniques. FT-IR spectroscopy revealed the band at 1720 cm− 1, which is the characteristic band of the esterification reaction between the polymer hydroxyl and carbonyl group of the crosslinker Succinic Acid (SA). The band intensity of C = O at nearly 1700 cm− 1 increased by increasing the PSSA@CNTs molar ratio. In addition, composite membranes had better swelling resistance, which can be confirmed by water contact angle and water uptake measurements. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) of surface topography reveal pores on the surface of cross-linked composite membranes, which do not extend through the membrane. This may explain the efficient proton conduction while minimizing methanol crossover. Uniform PSSA@CNTs dispersion in PVA enhanced the mechanical, proton conductivity, and thermal characteristics, which decreased the methanol crossover through the membrane compared to the pristine PVA membrane. The mechanical properties of the prepared membranes by adding PSSA@CNTs are found to improve tensile strength significantly by about 60%. Thermal stability improvements in the composite-prepared membranes were demonstrated through thermogravimetric analysis (TGA). Therefore, PVA/1%PSSA@CNTs-SA membranes showed more desirable properties as a polyelectrolyte membrane with (3.03 meq/g) ion exchange capacity (IEC), water uptake value of (45.11%), and proton conductivity (6.12 × 10− 2 S.cm− 1). Therefore, the produced membranes exhibit self-extinguish ability and high efficacy with admissible conductivity for electrochemical applications.