Ultrathin gelatin films were prepared by filtering gelatin on a porous nanofibrous scaffold and cross-linked by glutaraldehyde. The gelatin thin films were obtained by using a copper hydroxide nanostrand scaffold after removal of the scaffold. At relative high pressure, the rejection properties of these gelatin films became worse due to mechanical fouling. However, the gelatin/carbon nanotube composite thin films prepared on a single-walled carbon nanotube scaffold could sustain a pressure up to 18 bars with more than 90% rejection for 2–3 nm molecules. The carbon nanotube layer dramatically increased the mechanical properties of the gelatin layer. The pressure dynamically controlled the network structure of the gelatin layer. The corresponding separation performances were investigated in detail. The gelatin films could be as thin as 62 nm. These gelatin films can separate 865 Dalton Direct Yellow 50 molecules at a rate of magnitude one to two orders higher than that of commercially available membranes with similar rejections.
