2905-61-5Relevant articles and documents
Synthesis and investigation of sulfonated poly(: P -phenylene)-based ionomers with precisely controlled ion exchange capacity for use as polymer electrolyte membranes
Rikukawa, Masahiro,Takahashi, Satoshi,Takeoka, Yuko,Yoshida-Hirahara, Miru,Yoshizawa-Fujita, Masahiro
, p. 12810 - 12822 (2020/04/22)
To achieve precise control of sulfonated polymer structures, a series of poly(p-phenylene)-based ionomers with well-controlled ion exchange capacities (IECs) were synthesised via a three-step technique: (1) preceding sulfonation of the monomer with a protecting group, (2) nickel(0) catalysed coupling polymerisation, and (3) cleavage of the protecting group of the polymers. 2,2-Dimethylpropyl-4-[4-(2,5-dichlorobenzoyl)phenoxy]benzenesulfonate (NS-DPBP) was synthesised as the preceding sulfonated monomer by treatment with chlorosulfuric acid and neopentyl alcohol. NS-DPBP was readily soluble in various organic solvents and stable during the nickel(0) catalysed coupling reaction. Sulfonated poly(4-phenoxybenzoyl-1,4-phenylene) (S-PPBP) homopolymer and seven types of random copolymers (S-PPBP-co-PPBP) with different IECs were obtained by varying the stoichiometry of NS-DPBP. The IECs and weight average molecular weights (Mws) of ionomers were in the range of 0.41-2.84 meq. g-1 and 143 000-465 000 g mol-1, respectively. The water uptake, proton conductivities, and water diffusion properties of ionomers exhibited a strong IEC dependence. Upon increasing the IEC of S-PPBP-co-PPBPs from 0.86 to 2.40 meq. g-1, the conductivities increased from 6.9 × 10-6 S cm-1 to 1.8 × 10-1 S cm-1 at 90% RH. S-PPBP and S-PPBP-co-PPBP (4 : 1) with IEC values >2.40 meq. g-1 exhibited fast water diffusion (1.6 × 10-11 to 8.0 × 10-10 m2 s-1), and were comparable to commercial perfluorosulfuric acid polymers. When fully hydrated, the maximum power density and the limiting current density of membrane electrode assemblies (MEAs) prepared with S-PPBP-co-PPBP (4 : 1) were 712 mW cm-2 and 1840 mA cm-2, respectively.
Conformations, equilibrium thermodynamics and rotational barriers of secondary thiobenzanilides
Kozic, Ján,Novák, Zdeněk,?ímal, Václav,Profant, Václav,Kune?, Ji?í,Vin?ová, Jarmila
, p. 2072 - 2083 (2016/04/09)
The article deals with conformational behaviour of 2-methoxy-2′-hydroxythiobenzanilides. The CS-NH group of these compounds preferentially adopts the Z-conformation. Entropy favours the Z-conformer over the E-conformer, whereas enthalpy slightly favours the E-conformer over the Z-conformer. The rotational barrier about the CS-NH bond was determined to be (81.5±0.4) kJ/mol. No significant rotational barrier was found on the Ar-CS and Ar-NH bonds. All experimental outcomes are compared with the results of quantum-chemical calculations.
Anion conductive aromatic copolymers from dimethylaminomethylated monomers: Synthesis, properties, and applications in alkaline fuel cells
Akiyama, Ryo,Yokota, Naoki,Nishino, Eriko,Asazawa, Koichiro,Miyatake, Kenji
, p. 4480 - 4489 (2016/07/07)
A novel series of anion conductive aromatic copolymers were synthesized from preaminated monomers (2,5-, 3,5-, or 2,4-dichloro-N,N-dimethylbenzylamine), and their properties were investigated for alkaline fuel cell applications. The targeted copolymers (QPE-bl-11a, -11b, and -11c) were synthesized via nickel-mediated Ullmann coupling polymerization, followed by quaternization and ion exchange reactions. Unlike the conventional method involving chloromethylation or bromination, this method provided copolymers with well-defined chemical structure. The hydrophilic components of the copolymers were composed of chemically stable phenylene main chain modified with high-density ammonium groups. Oligo(arylene ether sulfone ketone)s were employed as a hydrophobic block. QPE-bl-11a gave tough and bendable membranes by solution casting. The obtained membrane with the highest ion exchange capacity value (IEC = 2.47 mequiv g-1) showed high hydroxide ion conductivity (130 mS cm-1) in water at 80 °C. The QPE-bl-11a membrane showed reasonable alkaline stability in 1 M KOH aqueous solution for 1000 h at 60 °C. A platinum-free fuel cell was successfully operated with hydrazine as a fuel, the QPE-bl-11a as a membrane, and an electrode binder. The maximum power density of 380 mW cm-2 was achieved at a current density of 1020 mA cm-2 with O2.