An efficient synthetic procedure for the phosphonation of aromatic polymers was developed and is here exemplified for polyphenylsulfone. This procedure involved the bromination of the polymer and the subsequent bromine‐phosphorus exchange by means of a Pd(0)‐catalyzed PC coupling reaction. In the resulting product, the phosphonate ester pendant groups were attached to aromatic rings of the polymer chain without alkylene spacer units. A substitution degree of almost one phosphonate moiety per repeating unit of the polymer was achieved in the presence of Pd2(dba)3 · CHCl3 as catalyst at 120 °C. Polymers with free phosphonic acid groups were prepared by ester hydrolysis. magnified image

Catalyst layers for direct methanol fuel cells (DMFC) must possess a complex structure in order to provide protonic and electronic conductivity as well as access to reactants at all reactive sites. This involves a highly porous structure, which is often mechanically instable, especially when mass production processes are utilized. A feasible process should provide a catalyst layer in one coating step and must include relatively fast drying of the catalyst ink.In the present work, different types of additives are used to provide such an ink. Inorganic particles that are much larger than the catalyst particles provide dimensional stability in the catalyst layer. Depending on their structure and surface, they can also be used to influence the porosity or hydrophobicity of the layers, and thus to optimize performance.Gel forming polymers are used to adjust the viscosity of the inks and since they also act as a binder, they help to stabilize the catalyst layers. These effects can be obtained by using minimal quantities of polymers, thus avoiding problems such as pore clogging or the deactivation of catalyst surfaces.As a result, catalyst inks can be adjusted to suit coating techniques such as knife‐coating or screen‐printing. Also, catalyst layers are mechanically stable, thus avoiding long‐term degradation due to crack formation or delamination.

Five new (Z)-2-alkoxyvinyl acetates (isopropyl, butyl, hexyl, decyl, and 10-undecenyl derivatives) have been prepared by a retro-Diels−Alder technique. The synthesis of typical detergent derivatives with long alkyl residues is markedly improved by using cyclopentadiene instead of anthracene for the Diels−Alder reaction. Amphiphilic polymers were obtained by cationic homopolymerization of the long-chain derivatives. As a result of their molecular arrangement, these polymers show a decidedly hydrophobic character. However, a highly water-soluble polymer with detergent properties resulted if the amphiphilic geometry of the homopolymer of the 10-undecenyl derivative was changed by oxidative cleavage of the terminal side-chain double bond.

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