Sulfonated Poly phenylene oxide

As an aromatic polymer, PPO can be sulfonated using concentrated sulfuric acid, chlorosulfonic acid, pure or complex sulfur trioxide, or acetyl sulfate [413—419]. The sulfonation can be easily controlled by adjusting time, temperature, concentration, and solvents. Sulfonated PPO (sPPO) has been considered as a good proton 

TABLE 3.12 Contact Angles, lECs, Water Uptake Values, and Proton Conductivities of sPPO Membranes and Naflon 112 [420] 

38 Effect of draw ratio on the conductivities of sPPO membranes (25 2°C fully hydrated DS 17.3, 30.7, and 40.7%). (Reprinted with permission from Elsevier (2007). Copyright 2007 Elsevier [422].) 

The conductivity can also be enhanced by doping sPPO with inorganic acids [423-425]. Guan and coworkers have developed such composite membranes for DMFCs [423,424]. They dissolved sPPO in NMP and meanwhile added a doping agent (phosphosdicate sol), which was prepared from H3PO4 and 2-propanol diluted 

TABLE 3.13 Proton Conductivities of sPPO Membranes Doped with Phosphosilicate Gel at Room Temperature and in Fully Hydrated State 

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To date, much effort has been undertaken to develop new alternatives. For example, sulfonated aromatic polymers, i.e., polymers with the sulfonic acid groups directly attached to the main chain or carrying short pendant side chains with terminal sulfonic acid units, attract increasing interest because of their chemical and thermal stability, and the ease of the sulfonation procedure. Some of the proposed polymers are sulfonated polysulfone (SPSU) [134] sulfonated poly(phenylene oxide) (SPPO) [135] sulfonated poly-(ether ether ketone) (SPEEK) [136] poly(phenylquinoxaline) (PPQ) [137] and poly(benzeneimidazole) (PBI) [138],... 

F. Hamad, G. Chowdhury, and T. Matsuura. Effect of metal cations on the gas separation performance of sulfonated poly (phenylene oxide) membranes. Desalination, 145(l-3) 365-370, September 2002. 

M. Yoshimune, 1. Fujiwara, H. Suda, and K. Haraya. Gas transport properties of carbon molecular sieve membranes derived from metal containing sulfonated poly(phenylene oxide). Desalination, 193(l-3) 66-72, May 2006. 

Y. Liu, Q. Yu, J. Yuan, L. Ma, and Y. Wu. Bronsted acid-base polymer electrolyte membrane based on sulfonated poly(phenylene oxide) and imidazole. Eur. Polym. J., 42(9) 2199-2203, September 2006. 

C. Li, J. Liu, R. Guan, P. Zhang, and Q. Zhang. Effect of heating and stretching membrane on ionic conductivity of sulfonated poly(phenylene oxide). J. Membr. ScL, 287(2) 180-186, January 2007. 

Another method of preparing nanofiltration membranes is to dip-coat a thin layer of sulfonated poly(phenylene oxide) (SPPO) [17], sulfonated polysulfone (SPS) [18], or carboxylated polysulfone [19] on a porous substrate membrane. The sulfonic acid groups in SPPO and SPS also become negatively charged with -SO3 groups upon dissociation. Sulfonic acid is a stronger acid than carboxylic acid. 

Another kind of TFC NF membrane was studied by Hamza et al. [5] using AFM. Membranes were prepared by applying a thin coat of sulfonated poly(phenylene oxide) solution to a porous substrate poly(ether sulfone), followed by solvent evaporation. Mixtures of chloroform/methanol with different ratios were used as solvents. The authors reported that the nodule size decreased with an increase in chloroform concentration in the solvent mixture. In the separation experiment of sodium chloride solute, the flux decreased from 11 to less than 2 x 10 m m s as the chloroform concentration increased from 0 to 66%. Thus, the decrease in flux parallels the decrease in the nodule size. Although they did not report the surface roughness. 

SPPOH Sulfonated poly(phenylene oxide) in hydrogen form... 

Liu Y, Yu Q, Wu Y. More studies on the sulfonated poly(phenylene oxide)+imidazole bronsted acid-base polymer electrolyte membrane. J Phys Chem Solids 2007 68(2) 201-5. 

X. Tongwen, Y. Weihua, H. Binglin, Ionic conductivity threshold in sulfonated poly (phenylene oxide) matrices A combination of three-phase model and percolation theory, Chem. Eng. Sci. 56... 

Wang, C.Q., Huang, Y.H., Cong, G.M. (1995) Preparation and characterization of sulfonated poly(phenylene oxide). Polymer Journal, 27, 173-178. 

Yang, S., Gong, C., Guan, R., Zou, H., Dai, H. (2006) Sulfonated poly(phenylene oxide) membranes as promising materials for new proton exchange membranes. Polymers for Advanced Technologies, 17, 360 365. 

Lu, D., Lu, W., Li, C., Liu, J., Guan, R. (2007) Composite membrane of sulfonated poly (phenylene oxide) doped with phosphosilicate gels for direct methanol fuel cell. Polymer Bulletin, 58, 673 82. 

Pan, Y., Xue, F. (2001) Lightly sulfonated poly(phenylene oxide)/poly(styrene-co-4-vinyl pyridine) blend interpolymer interaction and miscibility. European Polymer Journal, 37, 247-249. 

Huang RYM, Kim JJ. Synthesis and transport properties of thin film composite membranes. II. Preparation of sulfonated poly(phenylene oxide) thin film composite membranes for the purification of Alberta tar sands waste waters. J. Appl. Pol Sci. 1984 29 4029-35. 

Polotskaya GA, Agranova SA, Antonova TA, Elyashevich GK. Gas transport and structural features of sulfonated poly(phenylene oxide). J. Appl. Polym. Sci., 1997 66 1439-43. 

Cabasso I, Yuan Y, Mittelsteadt C. Blend membranes based on sulfonated poly(phenylene oxide) for enhanced polymer electrochemical cells. US Patent 5,989,742 (1999). 

Kruczek, Boguslaw, Development and Characterization of Dense Membranes for Gas Separation Made from High Molecular Weight Sulfonated Poly (Phenylene Oxide). Effect of Casting Connditions on the Morphology and Performance of the Membranes, Ph.D. Thesis, University of Ottawa, Ottawa ON 1999. 

R. Y.M. Huang and J.J. Kim, Synthesis and Transport Properties of Thin Film Composite Membranes, II, Preparation of Sulfonated Poly (phenylene oxide) Thin Film Composite Membranes for the Purification of Alberta Tar Sands Waste Waters, J. Appl. Polym. Sci., 1984, 29, 4029-4035. 

A.K. Agarwal and R.Y.M. Huang, Studies on the Enhancement of Separation Characteristics of Sulfonated Poly (Phenylene oxide)/PolysuIfone Thin Film Composite Membranes for Reverse Osmosis Applications II. Effects of Nitromethane and the Chemical Treatment Combined with Gamma-Ray Irradiation, Angewandte Makromol. Chem., 1988,163, 15-21. 

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