Synthesis and Properties of Cationic Multiblock Polyaramides and Polyimides

Polydiallyldimethylammonium chloride (PDADMAC) is a useful material due to its high charge density and alkaline stability, but its hydrophilic nature limits applications to those where a dissolved polymer is suitable. To make polymers containing the diallyldimethylammonium moiety for applications as films and membranes, multiblock copolymers of polyaramides and polyimides, materials known for their excellent physical properties, were synthesized. Aminophenyl difunctionalized PDADMAC was synthesized using a disulfide iniferter then counterion exchanged to the hexafluorophosphate anion to produce telechelic oligomers with good solubility in polar aprotic solvents. The oligomers were reacted in-situ with the proper difunctional monomers to produce poly(ether)aramides and poly(ether)imides. The copolymers were synthesized at high yield over a range of compositions and the material properties resulted from both the backbone chemistry and composition. Several of the copolymers formed films with good clarity, strength, and flexibility. The copolymers containing ether linkages had increased backbone flexibility and better film properties. The multiblock copolymers demonstrate a method to produce materials with good thermal stability, strength, and flexibility, making them uniquely capable of serving as water insoluble, cationic films and membranes.