Electrospun Hybrid Perfluorosulfonic Acid/Sulfonated Silica Composite Membranes

• Published in: Membranes (Basel) Vol. 10; no. 10; p. 250
• Main Authors: Santos, Leslie, Powers, Devon, Wycisk, Ryszard, Pintauro, Peter
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 23.09.2020; MDPI
• Subjects: Acids; BASIC BIOLOGICAL SCIENCES; biochemistry & molecular biology; chemistry; Conductivity; Electrospinning; ENGINEERING; Fibers; Fluorides; fuel cell membranes; Fuel cells; Humidity; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ionomers; MATERIALS SCIENCE; Mechanical properties; Membranes; Nanofibers; Perfluoro compounds; polymer science; Polymers; Polyvinylidene fluorides; Protons; Reinforcing fibers; Relative humidity; Silica; Silicon dioxide; sol-gel silica; Swelling; Vinylidene fluoride; United States > US
• ISSN: 2077-0375; 2077-0375
• DOI: 10.3390/membranes10100250

Electrospinning was employed to fabricate composite membranes containing perfluorosulfonic acid (PFSA) ionomer, poly(vinylidene fluoride) (PVDF) reinforcement and a sulfonated silica network, where the latter was incorporated either in the PFSA matrix or in the PVDF fibers. The best membrane, in terms of proton conductivity, was made by incorporating the sulfonated silica network in PFSA fibers (Type-A) while the lowest conductivity membrane was obtained when sulfonated silica was incorporated into the reinforcing PVDF fibers (Type-B). A Type-A membrane containing 65 wt.% PFSA with an embedded sulfonated silica network (at 15 wt.%) and with 20 wt.% PVDF reinforcing fibers proved superior to the pristine PFSA membrane in terms of both the proton conductivity in the 30–90% RH at 80 °C (a 25–35% increase) and lateral swelling (a 68% reduction). In addition, it was demonstrated that a Type-A membrane was superior to that of a neat 660 EW perfluoroimide acid (PFIA, from 3M Co.) films with respect to swelling and mechanical strength, while having a similar proton conductivity vs. relative humidity profile. This study demonstrates that an electrospun nanofiber composite membrane with a sulfonated silica network added to moderately low EW PFSA fibers is a viable alternative to an ultra-low EW fluorinated ionomer PEM, in terms of properties relevant to fuel cell applications.