Poly(diallyldimethylammonium chloride) (PDADMAC) is a useful material due to its high charge density and alkaline stability, but its hydrophilic nature limits applications to those where the dissolved polymer is appropriate. To make polymers suitable for applications as films and membranes containing the diallyldimethylammonium moiety, multiblock copolymers of polyaramides (PA) and polyimides (PI), materials known for their excellent physical properties and stabilities, were synthesized. Aminophenyl difunctionalized PDADMAC oligomers were 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 PA, polyetheraramides, PI, and polyetherimides. All the classes of copolymers were synthesized over a range of compositions at high yield and material properties were demonstrated to be a result of both the backbone chemistry and the composition. Several of the synthesized copolymers formed films with good clarity, strength, and flexibility. The copolymers containing ether linkages had increased backbone flexibility and demonstrated better film‐forming properties. The multiblock copolyaramides and copolyimides demonstrate a method to produce materials with excellent thermal stability and good strength and flexibility, making them uniquely capable of serving as water insoluble, cationic films, and membranes.

This work presents the radical copolymerization of diallyldimethylammonium hexafluorophosphate (DADMA­(PF6)) and methyl methacrylate (MMA) with minimal added solvent. The ion exchange of DADMAC from chloride to hexafluorophosphate yielded a water-insoluble form of the ammonium monomer that is soluble in MMA. Copolymerizations were successfully carried out over a wide range of monomer feed ratios, which correlated strongly to the composition of the final copolymer and made it possible to incorporate large percentages of either monomer. Studies of copolymer composition at a range of reaction times indicated that the incorporation of MMA was slightly favored over that of DADMA­(PF6). While all copolymers formed water-insoluble stand-alone films, qualitative examination of the films demonstrated that those with high incorporations of MMA had greater flexibility and optical clarity. A facile, reproducible polymerization method developed herein produced copolymers containing diallyldimethylammonium moieties that can be processed into water-insoluble polymer films for potential membrane applications.

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Research in anion exchange membranes (AEM)­s has continued with the development of materials bearing base stable cations. Designing AEMs that microphase separate into hydroxide conductive, hydrophilic domains within a hydrophobic and mechanically robust matrix has been shown to be successful for improving AEM performance. A series of multiblock polysulfone-poly­(diallylpiperidinium hydroxide) copolymers (PSf-PDApipOH) of similar hydrophobic/hydrophilic composition was prepared in which the molecular weight of the hydroxide conducting PDApipOH segments was varied. The variable hydrophilic segment molecular weight was designed to assess the impact on microphase separation, hydroxide conductivity, and water management. The multiblock copolymers investigated were prepared by condensation polymerization of preformed 4-fluorophenyl sulfone terminated poly­(diallylpiperidinium hexafluorophosphate) (PDApipPF6) oligomers with polysulfone monomers. The structure–property relationship between the molecular weight of the conductive PDApipOH segments and AEM performance was demonstrated by evaluation of the microphase separation, water uptake, and hydroxide conductivity. Membranes fabricated from the polysulfone-poly­(diallylpiperidinium hexafluorophosphate) (PSf-PDApipPF6) multiblock copolymers were shown to form well-connected conductive domains by SAXS and atomic force microscopy experiments. The PSf-PDApipOH membranes were highly conductive with the maximum hydroxide conductivity reaching 62.9 mS·cm–1 at 60 °C and 95% relative humidity. Furthermore, it was demonstrated that the conductivity increased with increasing PDApipOH segment molecular weight.