Synthesizing nanotubes using porous alumina or polycarbonate membranes as template has been a popular method. In this study, polymer nanotubes were prepared by sequentially depositing two polymers capable of forming inter-chain covalent bonds in porous alumina. To avoid coagulation at neutral pH after removing the template, the nanotubes were stabilized in water with adsorbed polyelectrolytes. We then prepared uniform thin films from the nanotube dispersions. The microstructure and physical properties of these films were characterized using several methods. In particular, we found the films to have different water vapor permeabilities, depending on the stabilizing polymer. Our nanotube networks have potential use as functionalized membranes with tunable permeability and selectivity. With variable composition, surface chemistry and nanotube dimension, these films are also ideal for testing theories of paper physics, such as the contributions of fiber strength and inter-fiber bonding to the overall strength.