A general approach for construction of asymmetric modification membranes for gated flow nanochannels†
The asymmetrical distribution of specific proteins on both sides the cell membrane, which is used to adjust the ion permeability, is magical inside the body of a living creature. These porous membrane materials with asymmetric micro/nanochannels are very common and important in both nature and artificial materials. Inspired by this, the construction of intelligent nanodevices with multifunctional properties is urgent and significant. Here a general strategy based on simultaneous chemical polymerization reactions in both sides of an anodic aluminum oxide (AAO) membrane is reported, combining with atom transfer radical polymerization (ATRP), dopamine self-polymerization (DOP-SP) and ring-opening metathesis polymerization (ROMP) technologies, to form various asymmetric membranes in the AAO nanochannels. By this method, double hydrophilic poly(3-sulfopropyl methacrylate potassium salt)@poly(2-(methacryloyloxy)ethyl-methylammonium chloride) (PSPMA@PMETAC), temperature and pH double responsive poly(N-isopropylacrylamide)@poly(dimethylamino)ethyl methacrylate (PNIPAM@PDMAEMA), and hydrophilic/hydrophobic poly(3-sulfopropyl methacrylate potassium salt)@poly(hydrophobic pentadecafluorooctyl-5-norbornene-2-carboxylate) (PSPMA@PNCA-F15) polymer brushes-modified asymmetrical AAO nanochannel array membranes were successfully prepared. Moreover, after the in situ ion exchange and reduction reaction of the double hydrophilic PSPMA@PMETAC membrane, we prepared polymer brushes-stabilized Au–Pd asymmetrically-modified AAO nanochannels, showing excellent flow-through catalysis.