Phenylene sulfuric acid functionalization

Yang et al. [139] reported the sulfuric acid functionalization of a phenylene-silica PMO involving the attachment of propyl sulfuric acid groups to the hydrophilic silica layers. In this material, as the catalytic acid sites and the hydrophobic benzene sites were apart from each other on the mesoporous surfece, a dimensionally designed surface structure with better catalytic environment resulted. The sulfuric acid-functionalized PMO was derived from a phenylene-silica... 

FI G U RE 10.44 Clearing temperature (Tc) as a function of polymer concentration for cellulose (DP = 800) in anhydrous phosphoric acid (74.4% w/w P2O5, solid circles). (From Boerstoel, H., Liquid Cystalline Solutions of Cellulose in Phosphoric Acid for Preparing. Cellulose Yarns, Ph.D. dissertation, University of Groningen, 1998.). Open circles represent the clearing temperature for poly(p-phenylene terephthalamide) (M, = 31,000 g/mol) in sulfuric acid (From Picken, S.J., Macromolecules, 22, 1766, 1989.). The square represents the clearing temperature for chitin (Af = 400,000 g/mol) solution at the polymer concentration of 15.5% w/w. 

Sulfonated aromatic polymers have been widely studied as alternatives to Nafion due to potentially attractive mechanical properties, thermal and chemical stability, and commercial availability of the base aromatic polymers. Aromatic polymers studied in fuel cell apphcations include sulfonated poly(p-phenylene)s, sulfonated polysulfones, sulfonated poly(ether ether ke-tone)s (SPEEKs), sulfonated polyimides (SPIs), sulfonated polyphosphazenes, and sulfonated polybenzimidazoles. Representative chemical structures of sulfonated aromatic polymers are shown in Scheme 3. Aromatic polymers are readily sulfonated using concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, or sulfur trioxide. Post-sulfonation reactions suffer from a lack of control over the degree and location of functionalization, and the... 

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