Synthesis, Preparation, and Performance of Blends and Composites of π-Conjugated Polymers and their Copolymers in DMFCs

π-conjugated aromatic polymers (π-CPs) are a class of high performance materials used in fabrication of a number of devices. Their use in direct methanol fuel cells (DMFCs) has resulted in improving the performance of this prospective alternative energy harnessing device. This review focuses on these aspects of π-CPs, from fabrication techniques to structure-property relationships and finally performance evaluation and comparison with other potential candidates. Along with an overview of the step-by-step progress that has been made in the last two decades, this review consists of a separate section dedicated to the advancements made in the last five years. This period has seen considerable progress in terms of preparation techniques, such as fabrication of layer-by-layer assembly and core-shell assembly; materials used, such as variety of dopants for π-CPs and sulfonated polymers in case of PEMs and π-CP composites with carbon nanotubes and graphenes in case of catalyst supporting matrices; and surface morphology, such as use of nanofibers, nanotubes, and nanowires. In addition, different polymerization strategies and solubility aspects of π-CPs have also been discussed. All these modifications have resulted in yielding high power and current densities, mass specific activity, stability, durability, and judicious utilization of costly materials, like Pt and Nafion.