Preparation and characterization of PVDF‐based blend membranes as polymer electrolyte membranes in fuel cells: Study of factor affecting the proton conductivity behavior

Abstract

There is a huge demand especially for polyvinylidene fluoride (PVDF) and its copolymers to provide high performance solid polymer electrolytes for use as an electrolyte in energy supply systems. In this regard, the blending approach was used to prepare PVDF-based proton exchange membranes and focused on the study of factor affecting their proton conductivity behavior. Thus, a series of copolymers consisting of poly (methyl methacrylate) (PMMA), polyacrylonitrile (PAN), and poly(2-acrylamido-2methyl-l-propanesulfonic acid) (PAMPS) as sulfonated segments were synthesized and blended with PVDF matrix in order to create proton transport sites in PVDF matrix.It was found that addition of PMMA-co-PAMPS and PAN-co-PAMPS copolymers resulted in a significant increase in porosity, which favored the water uptake and proton transport at ambient temperature. Furthermore, crystallinity degree of the PVDF-based blend membranes was increased by addition of the related copolymers, which is mainly attributed to formation of hydrogen bonding interaction between PVDF matrix and the synthesized copolymers, and led to a slight decrease in proton conductivity behavior of blend membranes. From impedance data, the proton conductivity of the PVDF/PMMAco-PAMPS and PVDF/PAN-co-PAMPS blend membranes increases to 10 and 8.4 mS cm −1 by adding only 50% of the related copolymer (at 25°C), respectively. Also, the blend membranes containing 30% sulfonated copolymers showed a power density as high as 34.30 and 30.10 mW cm −2 at peak current density of 140 and 79.45 mA cm −2 for the PVDF/PMMA-co-PAMPS and PVDF/PAN-co-PAMPS blend membranes, respectively. A reduction in the tensile strength was observed by the addition of amphiphilic copolymer, whereas the elongation at break of all blend membranes was raised. up, low operation temperature, and simplicity. Polymer electrolyte membrane (PEM), as one of the important parts of a PEMFC, has attracted a considerable attention. The performances of this part of PEMFCs are affected by its proton conductivity, electrical insulating, chemical and thermal stability, electro-osmotic drag coefficient, and good mechanical properties. Perfluorinated polymer membrane, known as Nafion, has been widely used as the proton exchange membrane in PEMFCs due to its excellent performances and stabilities. 6 However, the main limitation of Nafion is its high cost and decreasing proton conductivity at temperature above 100°C and low humidity condition, which limit its application. For this reason, introducing a new polymeric membrane is one of the key issues and research priorities in the field of PEMFCs.Recently, there is an enormous request especially for polyvinylidene fluoride (PVDF) and its copolymers to prepare superior PEM for PEMFC application. 2,7-9 An account of a great backbone similarity between PVDF and commercial perfluorinated membranes such as Nafion, Dow, Aciplex, and Flemion membranes, the study of PVDF and its copolymers as a replacement for the costly fluorinated membranes has become one of the research pri...

Constructing Long-Range Transfer Pathways with Ordered Acid–Base Pairs for Highly Enhanced Proton Conduction

“…A strategy of acid–base composites offers potential to address these problems by forming acid–base pairs, which generate proton defects and then enable a fast Grotthuss-type proton transfer. − So far, the developed acid–base pairs are commonly divided into two categories. One is incorporating functionalized (acidic or basic) nanofillers into the (basic or acidic) polymer matrix. − Ueda et al obtained an 88% increase in anhydrous conductivity at 140 °C for the phosphoric acid-doped sulfonated poly­(ether ether ketone) (SPEEK) membrane (from 4.0 to 7.5 mS cm –1 ) with the introduction of 3 wt % polybenzimidazole (PBI)-grafted graphene oxide (GO) .…”

“…One is incorporating functionalized (acidic or basic) nanofillers into the (basic or acidic) polymer matrix. − Ueda et al obtained an 88% increase in anhydrous conductivity at 140 °C for the phosphoric acid-doped sulfonated poly­(ether ether ketone) (SPEEK) membrane (from 4.0 to 7.5 mS cm –1 ) with the introduction of 3 wt % polybenzimidazole (PBI)-grafted graphene oxide (GO) . The other is blending basic polymers (e.g., PBI, chitosan) with acidic polymers (e.g., sulfonated polysulfone, SPEEK). − Fu and co-workers blended SPEEK with benzimidazole-grafted polysulfone to prepare a composite membrane, which gave an enhanced proton conductivity of 0.2 mS cm –1 under anhydrous conditions in contrast to the plain SPEEK membrane (0.06 mS cm –1 ) at 120 °C . However, the conductivity enhancements of these membranes are limited, as the random distribution of acid–base sites diminish the corresponding synergistic effect of acid–base pairs in creating proton defects.…”

Evaluation of properties and performance of poly(ether sulfone ketone) membranes in proton exchange membrane fuel cells

“…Moreover, they have good thermal, mechanical, chemical stability, and good proton conductivity 20–22 . Besides, it has been proven that there is a close relationship between the structure and properties of these aromatic hydrocarbon polymers and their performance as a proton exchange membrane (PEM) 23,24 …”

Synthesis of Poly(2-Acrylamido-2-Methylpropane Sulfonic Acid) and its Block Copolymers with Methyl Methacrylate and 2-Hydroxyethyl Methacrylate by Quasiliving Radical Polymerization Catalyzed by a Cyclometalated Ruthenium(II) Complex

“…Poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) displays interesting properties that may lead to many potential applications. Such properties arise from the strongly ionizable sulfonate groups in its chemical structure, its pH-responsiveness and its swelling behavior [ 1 , 2 , 3 ] AMPS-containing polymers have been successfully applied in polyelectrolyte membrane fuel cells [ 1 ], as catalytic membranes for biodiesel production [ 4 ] and in medical applications due to their low toxicity, hydrolytic stability and antimicrobial activity against microorganisms [ 5 , 6 ]. Moreover, they are used in a wide range of industrial products such as cosmetics, coatings and adhesives, amongst others [ 7 ].…”