Development of Integrally Skinned Asymmetric Polyaniline Hollow Fibers for Membrane Applications

Fabricating integrally-skinned asymmetric hollow fiber membranes from concentrated polyaniline solutions is technically challenging due to the complex issues associated with rapid gelation of the polymer solution and controlling the phase inversion process to create porous structures. Different processing parameters, such as solution composition, coagulants, and spinning conditions were shown to dramatically affect the morphology of immersion-precipitated polyaniline hollow fiber membranes. This study revealed that it is possible to minimize macrovoid formation while controlling the thickness of the selective layer and the porosity of the support layer. Asymmetric polyaniline hollow fibers with morphologies that range from a highly permeable microporous interface to a dense selective layer have been successfully produced. The membrane properties can be tailored by doping the polyaniline hollow fiber with the desired dopant acid during the fiber-spinning process. Asymmetric integrally-skinned polyaniline hollow fiber membranes with an ultra-thin (<1 μm), defect-free selective layer have been produced on a continuous basis (150 m/h). Furthermore, the thickness of the dense layer can be systematically increased up to 30 μm for combined heat-mass transfer applications such as the dehumidification of air.