Multilayer composite surfaces prepared by an electrostatic self-assembly technique with quaternary ammonium salt and poly(acrylic acid) on poly(acrylonitrile-co-acrylic acid) membranes

An electrostatic self-assembly technique was applied to prepare ion complex polymer layers on polyacrylonitrile with acrylic acid segments {poly(acrylonitrile-co-acrylic acid) [P(AN-co-AA)]}. For the ionic complex layers, quaternary ammonium salts, such as cetyl trimethyl ammonium chloride (CTAC) and tetramethyl ammonium chloride (TMAC), were used as cationic species, and also, poly(acrylic acid) (PAA) was used as an anionic species. These cationic and anionic species were self-assembled alternately on the surface of the P(AN-co-AA) membrane. Fourier transform infrared spectroscopy, AFM, and water contact angle measurements of the membrane surface were used to confirm the formation of the multilayer composites on the P(AN-co-AA). The permeabilities of water and macromolecules of different molecular weights were evaluated by a membrane filtration technique. The values of permeability strongly depended on the formation layer by layer of these ion composites on the base P(AN-co-AA). Through the measurement of the values of the contact angle of water, it was clear that surface nature of the base membrane treated by CTAC or TMAC and PAA dramatically changed. We concluded that such an electrostatic self-assembly technique is useful for the preparation of multicomposite layers to modify the surface of base P(AN-co-AA) membranes.