| Polysulfone is a widely used high-performance engineering plastic because of its good mechanical and chemical stabilities. Even though polysulfone has excellent overall properties, the hydrophobic nature of the polymer precludes its broader use in membrane application where hydrophilic character is desired. Until now four post-modification methods of polysulfone have been reported: electrophilic sulfonation, chloromethylation, phthalimidomethylation, and lithiation with n-butyl lithium. However, all these methods suffer serious side reactions, such as chain cleavage and crosslinking of polymer chains, which can alter mechanical properties of the resulting polymer. We have developed a new post-functionalization method of polysulfone that utilizes transition metal catalyzed activation/functionalization of aromatic C--H bond. Based on viscosity measurement of the functionalized polysulfones, this new method does not result in negative effects on the polymer chain length. In addition, the pinacol boronic ester group that was installed on the polysulfone from the iridium-catalyzed aromatic C--H bond activation/functionalization can be converted to various polar functional groups, including ketone, siloxy, sulfonated ester, and amine, via one-step Suzuki-Miyaura coupling reaction. |
