Introduced here is a plasma polymerization apparatus. Example embodiments include a reaction chamber in a shape substantially symmetrical to a central axis. Some examples further include a rotation rack in the reaction chamber. The rotation rack may be operable to rotate relative to the reaction chamber about the central axis of the reaction chamber. Examples may further include reactive species discharge mechanisms positioned around a perimeter of the reaction chamber and configured to disperse reactive species into the reaction chamber in a substantially symmetrical manner from the outer perimeter of the reaction chamber toward the central axis of the reaction chamber, such that the reactive species form a polymeric coating on surfaces of the one or more substrates during said dispersion of the reactive species, and a collecting tube positioned along the central axis of the reaction chamber and having an air pressure lower than the reaction chamber.