Pendant sulfonic acid group

In 1971, E. I. Du Pont De Nemours Company, Inc. (DuPont) patented a linear aromatic polyamide with pendant sulfonic acid groups, which they commercialized as the Permasep B-9 and B-10 membranes (Permasep is a registered trademark of DuPont Company, Inc. Wilmington, DE). These membranes exhibited higher water flux at slightly lower operating pressures than cellulose acetate membranes. The membranes were cast as unique hollow fine fibers rather than in flat sheets or a tubes (see Chapter 4.3.4). 

Crosslinked polyether sulfone membranes containing pendant sulfonic acid groups were prepared by Michot [4] and used in electrochemical cells. 

Pittman et al. [29] described the simultaneous aldol condensation and the hydrogenation of the condensation product in a one-pot process with a perfluorinated aliphatic ether polymer with pendant sulfonic acid groups as the acid catalyst and Pd as the hydrogenation catalyst. Taking acetone and hydrogen as the educt components the aim was to obtain 4-methyl-2-pentanone for given reaction conditions. 

Nafion (Figure 4.12), a perfluorinated polymer containing pendant sulfonic acid groups, is generally considered to be a solid superacid whose pK ranges from -5 to -9. It was earlier shown to be an active catalyst for various organic reacfions such as alkylation, isomerization, disproportionation, transalkylation, acylation, nitration, hydration, rearrangement, and so on. ° ° ... 

Y. Gao, G.P. Robertson, M.D. Guiver, S.D. Mikhailenko, X. Li, S. Kaliaguine, Synthesis of poly(arylene ether ether ketone ketone) copolymers containing pendant sulfonic acid groups bonded to naphthalene as proton exchange membrane materials. Macromolecules 2004, 37(18), 6748-6754. 

Lee JK, Li W, Manthiram A (2009) Poly(arylene ether sulfone)s containing pendant sulfonic acid groups as membrane materials for direct methanol fuel cells. J Membr Sci 330 73-79... 

Copolymers with different amounts of pendant sulfonic acid groups have been synthesized by an aromatic substitution polymerization reaction [129]. 4,4-Difluorodiphenylsulfone, 6,7-dihydroxy-2-naph-thalenesulfonate, and various hydroxyl-terminated monomers were used in the presence of potassium carbonate [130]. 

Mohanty AK, Mistri EA, Ghosh A, Banerjee S. Synthesis and characterization of novel flu-orinated poly(arylene ether sulfone)s containing pendant sulfonic acid groups for proton exchange membrane materials. J Membr Sci 2012 409-410 145-55. 

Nitrile-functional (hexafluoroisopropylidene)diph-enol-based poly(arylene ether) copolymers with pendant sulfonic acid groups can be prepared by the copolymerization of 4,4 -(hexafluoroisopropyfidene) diphenol, 2,6-dichlorobenzonitrile, and 3,3 -disulfo-nate-4,4 -dichlorodiphenyl sulfone [9]. Hexafluoroi-sopropylidene diphenol is a fluorinated bisphenol A. 

Z. Bai, J.A. Shumaker, M.D. Houtz, P.A. Mirau, T.D. Dang, Ruorinated poly(arylenethioether sulfone) copolymers containing pendant sulfonic acid groups for proton exchange membrane materials. Polymer 50 (6) (2009) 1463-1469. 

Kim DS, Robertson GP, Kim YS, Guiver MD (2009) Copoly(aiylene ether)s containing pendant sulfonic acid groups as proton exchange membranes . Macromolecules 42 957. 

Zhou W, Yoshino M, Kita H, Okamoto K (2001) Carbon molecular sieve membranes derived from phenolic resin with a pendant sulfonic acid group. Ind Eng Chem Res 40 (22) 4801-... 

Based on the cluster network model, further studies propose an interpretation of the percolation properties of proton conductivity as a function of water content by using a random network model [102], which is a modification of the cluster network model. This model includes an intermediate region wherein the side chains ending with pendant sulfonic acid groups, which are bonded to the perfluorinated backbones, tend to form cluster within the overall structure of the material resulting in the formation of hydrated regions. Unlike the cluster network model, the... 

Yin, Y., Yamada, O., Suto, Y., Mishima, T., Tanaka, K., Kita, H., Okamoto, K.I. (2005) Synthesis and characterization of proton-conducting copolyimides bearing pendant sulfonic acid groups. Journal of Polymer Science Part A Polymer Chemistry, 43, 1545-1553. 

To overcome the problems of cellulose acetate membranes, many synthetic polymeric materials for reverse osmosis were proposed, but except for one material, none of them proved successful. The only one material, which could remain on the market, was the linear aromatic polyamide with pendant sulfonic acid groups, as shown in Figure 1.2. This material was proposed by DuPont, which fabricated very fine hollow fiber membranes the modules of this membrane were designated B-9 and B-10. They have a high rejection performance, which can be used for single-stage seawater desalination. They were widely used for mainly seawater or brackish water desalination and recovery of valuable materials such as electric deposition paints, until DuPont withdrew them from the market in 2001. 

Besides the use of dihalo sulfonated monomers, the Guiver group introduced several commercial sulfonated bisphenol monomers to prepare SPEK polymers. For example, sodium 6,7-dihydroxy-2-naphthalenesulfonate (DFINS) was purchased from Rintech, Inc. and recrystallized before use. The sulfonated poly(arylene ether ether ketone ketone) copolymer containing pendant sulfonic acid groups was... 

Kim et al. also synthesized PAEK bearing a pendant sulfonic acid group by reacting the activated carboxylic group with 2-aminoethanesulfonic acid or with the cross-linker disulfonic acid-benzidine diamines. The MEAs were fabricated for the cell performance test. CSPAEK membrane was inserted between the two electrodes, Pt/Ru (1/1) anode and Pt cathode, at the amount of 1.0 mg cm each. Nation solution (5 wt.%) was used to bind the membrane and catalyst. MEA was prepared under application of high pressure (1000 psi) for 1 min at 100°C. The cell test was conducted at 80°C. Methanol (2 M) was introduced at the anode side at 5 mL min and the oxygen to the cathode side at 200 mL min. The cell area was 6.25 cm . The maximum power density of Naflon 117 was 66.5 mW cm , whereas the 20% cross-linked membrane showed better performance, 71 mW cm . All the membranes OCVs equal to that of Naflon 117. 

Despite the significant work reported in the literature for these materials, there are few examples of the synthesis of zirconium phosphonates containing pendant acid groups and then-utilization as ion exchangers or as solid catalysts [refs. 5-8]. The ability to incorporate specific pendant functional groups into MELS provides opportunities for the development of several classes of novel solid acid catalysts. This paper provides an introduction to MELS materials, a description of synthetic methods used to produce solid MELS catalysts containing pendant sulfonic acid groups, and a discussion of some of the physical and catalytic properties of these materials. 

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