Phosphoric acid-doped ionic liquid-functionalized graphene oxide/sulfonated polyimide composites as proton exchange membrane

J. Polym. Sci. Part A: Polym. Chem.

Suleiman

2018

A novel aromatic block–graft copolymer of sulfonated poly(styrene–isobutylene–styrene)‐graft‐poly(vinyl phosphonic acid) (SIBS‐g‐PVPA SO3H) was synthetized for direct methanol fuel cell (DMFC) and chemical and biological protective clothing (CBPC) applications. The polystyrene (PS) blocks of SIBS were chloromethylated via a Friedel–Crafts reaction to obtain the macroinitiator SIBS‐CH2Cl. Atom transfer radical polymerization (ATRP) was performed to graft VPA to the chloromethylated groups of the macroinitiator and yield SIBS‐g‐PVPA, which was subsequently sulfonated using acetyl sulfate as the sulfonating agent. After each functionalization step, a membrane was prepared by using the solvent casting technique. The final membrane was composed of triblock SIBS as the backbone, PVPA grafts attached to the chloromethylated PS end blocks and sulfonic groups in the non‐chloromethylated PS units. A comprehensive materials characterization study (e.g., GPC, FTIR, TGA, EA) was performed to confirm proper functionalization of each material. Unique ionic interactions (i.e., crosslinking via formation of sulfonate–phosphonium complexes) arose between the phosphonic and sulfonic groups (i.e., PO3H2 and SO3H, respectively) that enhanced the water absorption capabilities, thermal and oxidative stability, and the transport properties of SIBS. The SIBS‐g‐PVPA SO3H membrane presented high Nafion® normalized selectivity and separation efficiency, indicating that this ionomer adequately functions for both applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1424–1435

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of novel phosphonated and sulfonated poly(styrene–isobutylene–styrene) for fuel cell and protective clothing applications

J. Polym. Sci. Part A: Polym. Chem.

Suleiman

2018

“…During the past years, many efforts have been made to develop new membranes based on nonfluorinated polymers as an alternative to Nafion as these are more cost‐effective . Alternative ionomers such as poly(phenylene), polysulfone, poly(ether ether ketone), polyimide, polyaniline, poly(arylene ether sulfone), poly(styrene‐ethylene/butylene‐styrene), to name a few, have been studied in an attempt to replace Nafion. However, these sulfonated polymers usually have lower proton conductivity than that of Nafion, because of the lower acidity of the sulfonic acid and less distinct phase separation between hydrophilic and hydrophobic domains .…”

Section: Introductionmentioning

confidence: 99%

Transport properties of blended sulfonated poly(styrene‐isobutylene‐styrene) and isopropyl phosphate membranes

J of Applied Polymer Sci

Suleiman

2018

This work discusses the effect of isopropyl phosphate (IP) on the transport properties of sulfonated poly(styrene-isobutylene-styrene) (SO 3 H SIBS) as membranes for direct methanol fuel cell (DMFC) and chemical and biological protective clothing (CBPC) applications. The properties were determined as a function of SIBS sulfonation level (i.e., 24, 34, 49, and 84 mol %) and IP loading (i.e., 1, 3, 5, 11, and 15 wt %). A comprehensive material characterization study (e.g., FTIR, TGA, AFM, and SAXS) was performed to confirm the presence of the phosphate groups in the polymer matrix, assess the thermal stability of the proton-exchange membranes (PEMs), and understand how the unique interactions between the phosphate and sulfonic groups influenced the nanostructure of SO 3 H SIBS. The transport properties, water absorption capabilities (i.e., swelling ratio, water uptake, etc.), oxidative stability, and ion-exchange capacity (IEC) were performed to evaluate the impact of IP on the properties of the resulting solvent-casted membranes. Results suggest that the morphology, thermal stability, and vapor permeability are governed by the sulfonation level, whereas the IEC, oxidative stability, water absorption capabilities, and the rest of the transport properties are dominated by the ionic content (i.e., sulfonic and phosphate groups) and their synergistic effects.

“…The major vibration bands associated with SO 3 H and Si − O stretching (both at ca . 1,100 cm −1 ) were overlapped by the 1,054 cm −1 band of GO and thus, could not be discriminated . Upon sulfonation, the intensity of the characteristic bands of GO was reduced.…”

Section: Resultsmentioning

confidence: 98%

Polymer Nanocomposite Membranes of Sulfonated Poly(Styrene‐Isobutylene‐Styrene) With Sulfonated Graphene Oxide for Fuel Cell and Protective Clothing Applications

Polymer Engineering & Sci

Ortiz-Negrón

et al. 2018

Graphene oxide (GO) and its sulfonated analog (sGO) have been incorporated into sulfonated poly(styrene‐isobutylene‐styrene) (SO3H SIBS) in order to enhance its water retention and proton conductivity, while aiming to block permeant passage through the material. The polymer nanocomposite membranes (PNMs) were tested for two applications: direct methanol fuel cell and chemical and biological protective clothing. The transport properties of the membranes were determined as a function of SIBS sulfonation level (i.e., 37, 61, and 88 mol%), filler type (i.e., GO and sGO) and filler loading (i.e., 1, 3, 5, and 10 wt%). Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed the functionalization and incorporation of the fillers into SO3H SIBS. No significant changes were observed in the thermal stability or FTIR spectra of the PNMs after addition of the fillers. Dissimilar behaviors were observed for the ion exchange capacity, water absorption capabilities and transport properties of the membranes after incorporation of the fillers. Atomic force microscopy (AFM) phase images and Fenton's test results indicate that the oxidative stability of the PNMs is associated to the interconnectivity between the hydrophilic domains of the fillers and SO3H SIBS. The PNMs presented low permeability and high proton conductivity and thus, functioned adequately for both applications. POLYM. ENG. SCI., 59:E455–E467, 2019. © 2018 Society of Plastics Engineers