Md. Awlad Hossain

Anion conductive aromatic ionomers containing a 1,2-dibenzoylbenzene moiety for alkaline fuel cell applications

Novel anion-exchange membranes with high conductivities have been prepared for application to alkaline fuel cells. A quaternary ammonium poly(dibenzoylbenzene ether sulfone) membrane was synthesized by chloromethylation, followed by substitution with trimethylamine with an ion-exchange reaction. The quaternary ammonium groups were selectively substituted in the para-position of the pendant phenyl groups of the dibenzoylbenzene unit. The di-quaternary ammonium hydroxide polymers showed an elevated molecular weight and exhibited excellent solubility in polar aprotic solvents. Quaternization and the subsequent ion-exchange reactions were quantitative such that the obtained ionomer membranes had a high ion-exchange capacity (IEC) of up to 1.69 mmolg−1. The resultant polymer membranes were studied by 1H NMR, FT-IR, thermogravimetric analysis (TGA), IEC, water uptake analysis, and ion conductivity analysis.

Preparation and characterization of sulfonated poly (ether sulfone)s containing hexabenzocoronene graphene moiety for PEMF

The novel sulfonated poly(ether sulfone)s containing hexabenzocoronene moiety that is partial graphene structure (SPGHPs) for polymer electrolyte membrane were synthesized and characterized their properties. Graphene is an allotrope of carbon and one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. Poly(ether sulfone)s containing hexaphenylbenzenes on polymer backbone were synthesized by poly condensation and followed intra-cyclization by friedel-craft reaction with lewis acid (FeCl3) to form partial graphene structure. The sulfonation was taken selectively on hexabenzocoronen units with concentrated sulfuric acid. The structure properties of the sulfonated polymers were investigated by 1H-NMR spectroscopy. The resulted ion exchange capacities (IEC) were 1.09~1.61 meq./g. The water uptakes were 8.84~15.27% at 30 °C and 18.27%~42.38% at 80 °C with changing the ion exchange capacities. The SPGHP membranes exhibit proton conductivities (80 °C, RH 90) of 78.3~105.7 mS/cm compared with 106.2 mS/cm of Nafion 211®.

Anion conductive imidazolium-based Parmax alkaline membrane for fuel cell applications

The anion exchange polyphenylene membrane containing imidazolium hydroxide ionic functional group was synthesized by sequential chloromethylation, substitution with 1-methylimidazole and ion exchange. The imidazolium hydroxide Parmax 1200 membrane has all carbon-carbon bonds without ether linkages, which would be chemically strong. The polyphenylene structure of Parmax provides a stiff and resistant backbone, whereas the pendant benzoyl group provides sites for chemical modifications. The resulting ionomer membrane showed ion exchange capacity (IEC) of 2.14 mmol g-1 with maximum chloromethylation yield. The imidazolium-functionalized copolymer membrane showed lower water affinity and high durability in alkaline condition. It exhibited hydroxide ion conductivity above 10-2 S cm-1 at room temperature and good chemical stability for up to seven days without significant losses of ion conductivity. The structural properties of the synthesized polymer membrane were investigated by 1H NMR spectroscopy and FT-IR. The membranes were studied by IEC, water uptake, and conductivity assessment.

Synthesis and properties of sulfonated poly(N-methylisatin-biphenylene) proton exchange membrane by superacid-catalyzed polymerization

A series of poly(phenylene)-based polyelectrolytes were synthesized from trifluoroacetophenone and N-methylisatin by superacid catalyzed polyhydroxyalkylation reaction. Postsulfonation of this high molecular weight and thermochemically stable poly(phenylene) with concentrated sulfuric acid resulted in homogeneous polyelectrolytes with controllable ion content (IEC: 1.40–2.39 meq./g). All these membranes were casted from dimethylsulfoxide (DMSO). The structural properties of the synthesized polymers were investigated by 1H NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, dimensional stability and proton conductivity assessment by comparing with Nation. The polymers containing fluoro group without ether linkage on polymer backbone were chemically stable towards nucleophiles (H 2 O, hydrogen peroxide, hydroxide anion and radical).

Nano Composite Membranes of Sulfonated Poly(ether sulfone)s Containing Tetraphenylethylene moiety and SiO2 for PEMFC

Conjugated cis/trans isomer-based polymer membranes were prepared with 25 mol% of bis (4-hydroxyphenyl)-1,2-diphenylethylene (BHDPE). BHDPE has a conjugated nonplanar conformation structure containing the peripheral four aromatic rings which facilitate the formation of π-π interactions. A series of sulfonated poly (ethersulfone) s (SPBHDPE) was synthesized with concentrated sulfuric acid. The sulfonation took place selectively on the BHDPE unit, and simultaneously on the side-chain and main-chain phenyl groups. The SPBHDPEs consisted of a 4:6 ratio of cis and trans form mixtures. Composite membranes were prepared with copolymers and SiO2 nanoparticles (20 nm, 4~10%wt). The composite membranes were cast from DMSO. A series of composite membranes structures and characteristic were evaluated by the 1H-NMR spectroscopy, and thermal stabilities. The membranes were performed by ion exchange capacity (IEC), water uptake and proton conductivity.

Nano Composite Membranes of Sulfonated Poly(ether sulfone)s Containing DHTPE and SiO2 for PEMFC

Sulfonated poly (ethersulfone) s (S-PDHTPEs) were prepared from 4,4-(2,2-diphenylethenylidene) bisphenol (DHTPE), 4,4-sulfonyldiphenol, 4-fluorophenylsulfone using potassium carbonate, and followed sulfonation reaction with conc. sulfuric acid. DHTPE is a conjugated structure, which enables to form planar conformation between aromatic rings, and selectively sufonated on phenyl rings of polymer side chain. Composite membranes were prepared with copolymers and SiO2 nanoparticles (20 nm, 4~10%wt). The composite membranes were cast from DMSO. A series of composite membranes structures and characteristic were evaluated by the 1H-NMR spectroscopy, and thermal stabilities. The membranes were performed by ion exchange capacity (IEC), water uptake and proton conductivity as a function of degree of sulfonation.