Synthesis and properties of soluble sulfonated polybenzimidazoles from 3,3′-disulfonate-4,4′-dicarboxylbiphenyl as proton exchange membranes

The Study of Water Sorption with Hydrolysis Lignin by Solid-State NMR Spectroscopy

Hydrolysis lignin is formed as a by-product of cellulose production and has limited industrial application. The ability of hydrolysis lignin to absorb and retain some water is important aspect for the study of its properties and modification methods. The processes of water sorption by hydrolysis lignin were studied with solid-state NMR spectroscopy. The samples were humidified in desiccators containing different saturated salts solutions with different relative air humidity above them. The sorption capacity of the samples was determined by water sorbed from the air, and it was found that lignin absorbs the amount of water equal to 40% of sample weight at maximum relative humidity of the air. The cross-polarization (CP) and magic angle spinning (MAS) methods were used to register solid-state NMR spectra. Using the 1H-NMR spectra, it was found that the hydrolysis lignin is hydrated in the whole volume, and the water penetrates into the deep layers of polymer, however, the distribution of water at the likely sorption sites is uneven. It was obtained with use of 13C-NMR spectroscopy that hydrolysis lignin hydrates in both hydrophilic and hydrophobic regions of the macromolecule, and the bulk of sorbed water (~64%) concentrates around the hydroxyl and methoxyl groups of lignin and polysaccharide residues.

Synthesis and Characterization of Highly Proton Conducting Sulfonated Polytriazoles

This article describes the synthesis and characterization of highly sulfonated polytriazole copolymers (PTSQSH-I to IV) with IEC_w values ranging from 2.41 to 3.49 mequiv g^-1. The copolymers were synthesized by click reaction between equimolar amount of a dialkyne monomer, potassium 2,5-bis(2-propyn-1-yloxy)benzenesulfonate, and a mixture of two different diazide monomers, 4,4-bis[3'-trifluoromethyl-4'(4-azidobenzoxy)benzyl]biphenyl and 4,4'-diazido-2,2'-stilbene disulfonic acid disodium salt. The copolymers were characterized by Fourier transform infrared and NMR spectroscopy techniques. The membranes were prepared by dissolving the salt form of the copolymers in dimethyl sulfoxide. The copolymers showed high thermal, mechanical, and oxidative stabilities, and the acidified membranes showed very high proton conductivity (43-173 and 132-304 mS cm^-1 at 30 and 80 °C, respectively). Transmission electron microscopy images confirmed the formation of well-phase-separated morphology with interconnected hydrophilic domains (20-150 nm).

New sulfonated copoly(triazole imide)s synthesized by a click chemistry reaction with improved oxidative stability

New sulfonated copoly(triazole imide)s synthesized by a click chemistry reaction with improved oxidative stability.

Synthesis, freestanding membrane formation, and properties of novel sulfonated hyperbranched polyimides

A novel six-membered ring hyperbranched polyimide (HBPI) has been synthesized by condensation polymerization of a difunctional monomer, 9,9-fluorenylidenebis(4,1-phenylene)bis(oxy)-4,4′-bis(1,8-naphthalic anhydride) (FBPNA), and a trifunctional monomer, tris(4-aminophenyl)amine (TAPA), at the molar ratio of FBPNA/TAPA = 1:1 in m-cresol at 180°C for 20 h. The resultant HBPI is further modified via end-capping reaction with 4-phenoxy-1,8-anhydride naphthalene (PNA). Post-sulfonation is performed in concentrated sulfuric acid at different temperatures (50, 60, and 70°C) for the pristine HBPI and 50°C for the PNA-modified polyimides to give various sulfonated HBPIs. Freestanding and tough membranes have been successfully fabricated by casting the polymer solutions containing a cross-linker, bisphenol A epoxy resin, at 80°C. The ion exchange capacities of the resultant membranes are in the range of 1.35–2.21 meq g−1 depending on the degree of chemical modification and the sulfonation conditions. Membrane properties such as water uptake, swelling ratio, proton conductivity, and radical oxidative stability are investigated.

Synthesis and characterization of highly fluorinated sulfonated polytriazoles for proton exchange membrane application

A series of polytriazole copolymers were synthesized by the click polymerization of fluorinated dialkyne with a mixture of two different diazide monomers and the proton exchange membrane properties of the copolymers were investigated.

Sulfonated organosilica mesocellular foam for catalyzing bulky molecules

Sulfonated organosilica mesocellular foam, a large-pore acidic catalyst, exhibited good catalytic activities in the hydrolysis of lab-extracted natural fibers or commercial microcrystalline celluloses, and esterification of oleic acid.

Novel composite membranes of triazole modified graphene oxide and polybenzimidazole for high temperature polymer electrolyte membrane fuel cell applications

Novel acid-doped membranes possessing improved proton conductivity and enhanced mechanical properties were prepared from polybenzimidazole and triazole modified graphene oxide.

Sulfonated poly(arylene ether sulfone)s with phosphine oxide moieties: a promising material for proton exchange membranes

Sulfonated poly(arylene ether sulfone)s with phosphine oxide moieties (sPESPO) were achieved by polycondensation of bis(4-hydroxyphenyl)phenylphosphine oxide with 3,3'-disulfonate-4,4'-difluorodiphenyl sulfone (SFDPS) and 4-fluorophenyl sulfone (FPSF). Sulfonated poly(arylene ether sulfone)s (sPES) were also synthesized by polymerization of 4,4'-sulfonyldiphenol with SFDPS and FPSF for comparison. The comparative study demonstrates that the sPESPO ionomers exhibit strong intermolecular interactions and high oxidative stability because of the phosphine oxide groups. Furthermore, the sPESPO membrane and the sPES membrane with an equal ion exchange capacity show much different nanophase separation morphology. As a result, the former shows better properties than the latter. The sPESPO membranes exhibit excellent overall properties. For instance, the sPESPO membrane, with a disulfonation degree of 45%, exhibits high thermal and oxidative stability. Moreover, it shows a water uptake of 30.8% and a swelling ratio of 15.8% as well as a proton conductivity of 0.087 S/cm at 80 degrees C.