Synthesis and characterization functionalized poly(ether ether ketone)s with carboxylic groups

A novel type of aromatic poly(ether ether ketone)s with carboxyl groups were prepared by polycondensation of 4,4-bis(4-hydroxyphenyl)pentanoic acid with difluoro-monomers. Their molecular structures were determined by ¹H-NMR and IR, respectively. Their molecular weights were measured by gel permeation chromatography (GPC), which showed that all the polymers had high molecule weights (>42.000). Due to the long side chains of polymers, all the polymers had good solubility (soluble in NMP, DMAc, THF, etc.). The differential scanning calorimeter (DSC) detected their excellent glass transition temperatures (T_g) up to 195.℃. The T_g increased with the content of carboxylic units in the polymer chains, because the interactions of H bonds increased with increasing content of carboxylic. The polymers could form transparent and flexible films, which make them a candidate for membrane materials.