(685e) Responsive Functionalized Membranes for Environmental Catalysis and Tunable Separations

Membrane based separation process has been widely used in water detoxification, water purification and waste water treatment. Stimuli-responsive polymers have been gained much attention due to their unique and excellent physical and chemical responses to changes in physiological conditions and have applied in different areas: such as, drug delivery, bioseparation and tissue engineering, etc. Various types of responsive membranes for regulated permeation have been devised, such as pH, temperature and light, etc. The porous membranes with responsive polymer chain have advantages over hydrogel membrane for mechanical strength and quick response to external signal. In our work, temperature (poly-N-isopropylacrylamide, NIPAAm) and pH (polyacrylic acid, PAA) responsive membrane has been designed and synthesized, in which pores open or close in response to temperature and pH values. Hydrophylized polyvinylidene fluoride (PVDF) membrane was used as support due to its chemical resistance properties and good thermal stability. In a narrow temperature or pH range, hydration-dehydration changes lead to the membrane conformation change, resulting in the stimuli-responsive permeability of gating membrane. The hydrophilic /hydrophobic transition of the membrane around response temperature and pH was investigated. The effects of temperature and pH on solute permeability and rejection were also determined. Besides pore-filling method, these temperature and pH responsive polymer were also covalently bonded with PVDF membrane with basified reaction followed with free-radical polymerization to enhance the stability of responsive polymers within the membrane. In addition, we also extended our work into catalytic area with immobilized nanoparticles in membrane platform for water detoxification.

       This research was supported by NIEHS-SRP and by DOE-KRCEE.